Salts - Science topic

PbCO₃ is quite insoluble and likely to occur in the described case.

Respected Mariana Colaço

To aliquot polymyxin B sulfate salt (P4932-1 MU) from Sigma-Aldrich, begin by preparing a stock solution of the desired concentration, following the instructions provided by Sigma-Aldrich or referencing the product datasheet. Once the stock solution is prepared, ensure proper sterilization techniques are employed to maintain purity and prevent contamination. Using an aseptic technique, dispense the desired volume of the stock solution into sterile aliquot tubes, taking care to avoid introducing air bubbles. Seal the aliquot tubes securely to prevent evaporation or contamination during storage. Label each aliquot tube with the date of preparation, concentration, and other relevant information. Store the aliquots at the recommended temperature and conditions specified by Sigma-Aldrich to maintain stability and functionality.

You can use a more polar solvent e.c., DMF where TEA hydrochloride dissolves fairly well. Alternatively, you can use Hunig's base (N-ethyl-N,N-diisopropylamine) in place of triethylamine. Hydrochlorides of Hunig's base are more readily soluble in organic solvents.

You should centrifigate the samples then dry them to prepare for TS

Dear Tom,

Maybe you should protect the hydroxyl group before amidation? Otherwise, the starting material 4-hydroxyphenylacetic acid will undergo esterification with itself.

Or you can use EDCI/DMAP/Et₃N to amidate them instead?

Вакуумно-паровая экстракция из сырья завода и оборудование «Альфа-Эфир-Вакуум» для получения вакуумных экстрактов.

Dear all, there are many possibilities to get the required MW. If you have the kinetics curve of the polymerization reaction, i. e., MW vs time or MW vs %conversion, then all to do is to quench the reaction at the time or % conversion corresponding to the targeted MW. The second solution is to do dialysis fractionation with a memebrane with the specific MW cut-off. The third possibility is to do mechanical degradation by shearing either by high speed agitator or passing through low porosity sieves.

If you want to avoid these extra work, choose a solvent with high transfer constant, and reduce the polymerization temperature. Starve feeding of the monomer may also help to reach a moderate MW. My Regards

I am having a similar problem to this now. Did you ever figure out why? Right not we are trying stirring.

Congratulations on your idea, creativity, and practice exercises with the younger generation!! I believe in previously advises. Consider doing X-ray diffraction measurement to confirm it.

Salt water does not evaporate faster than fresh water; in fact, fresh water always evaporates faster than salt water. This is because of the difference between the salt and water molecules. Water is a slightly volatile substance, meaning that it is capable of evaporation, while salt is a nonvolatile substance, so it is not as capable of evaporation.

Evaporation takes place on the surface of a substance. Fresh water has only water molecules on its surface area, which lets it evaporate easily. Salt water, on the other hand, has both salt and water molecules on its surface area. The salt molecules take up part of the surface area and prevent the water molecules from evaporating as quickly, which is why salt water always evaporates more slowly than fresh water.

There are 2 main reasons why the protein could be precipitating: electrostatic interactions or hydrophobic interactions.

Increasing the salt concentration would probably overcome electrostatic interactions. You would have to remove the salt later, which is easy to do by passing the column through a desalting column or by dialysis. Changing the pH by several units could also help, but you have explained why this is a less desirable approach for you.

In my opinion, the more likely reason for the insolubility is hydrophobic interactions, since the interior parts of proteins are hydrophobic. You could probably keep the protein in solution using a detergent, but removing detergent later can be troublesome. There are a few detergents that are compatible with mass spec, however. The other approach would be to add a strong chaotrope, either urea or guanidine-HCl, at several molar. These are small molecules that can be removed later. You would have to experiment to find the minimum necessary concentration to keep the Zn²⁺-free protein in solution, especially if you don't want to completely unfold the protein, since refolding a completely denatured protein can be a challenge.

To estimate carbon stocks in salt marshes, seagrasses, or mangroves, you typically conduct field measurements and use established methods such as:Vegetation Surveys: Measure the biomass and density of plant species in the area.Soil Sampling: Collect soil cores to measure carbon content at different depths.Remote Sensing: Use satellite imagery or aerial surveys to estimate vegetation cover and biomass.Allometric Equations: Utilize equations that relate plant size (e.g., diameter, height) to biomass.Carbon Content Analysis: Analyze collected plant and soil samples in the laboratory to determine carbon content.GIS Mapping: Combine field data with geographic information system (GIS) tools to create spatial maps of carbon stocks.

The dielectric constant tells us how well a solvent can decrease the force between charged particles. Basically, a high dielectric constant means the solvent is really good at pulling ions apart, which usually makes it easier for salts to dissolve in it. Water is a prime example—it has a high dielectric constant, making it excellent for dissolving many salts.

But, the story doesn't end there. Several other factors play into how well a salt dissolves:

For NaCl and similar salts, water's super high dielectric constant plus its knack for forming strong hydrogen bonds make it especially good at dissolving salts. Adding another solvent into the mix, whether it's formamide (which has a different way of bonding despite its high dielectric constant) or ethanol (which has a lower dielectric constant and isn't as good at stabilizing ions), tends to mess up the delicate balance that makes water so effective on its own, usually making the salt less soluble.

The fact that no added solvent makes NaCl more soluble than it is in pure water highlights how uniquely suited water is for dissolving ionic compounds like salts.

Dear Aria Mcullum

I'm agree with Adam B Shapiro

since in general the affinity of metalloproteins is in micro molar range is it possible that at the end of purification process, you will obtain an apo or partially metallated form, expecially if you are using for purification approaches as IMAC where there are also different metals that can interfeere.

I suggest to you to produce apo form by incubating the protein with EDTA, remove the EDTA by desalting and add again the metal.

you can use DSF and check how the tm change under metal addition to check if the protein bind the metal..

in the following paper you can find an example of this on the following paper

good luck

Manuele

This is a fascinating application. Let's delve into the option:

1. Ag/AgCl Electrode:

○ The Ag/AgCl electrode is widely used as a reference electrode in electrochemical measurements.

○ It provides a stable and reproducible reference potential.

○ The Ag/AgCl system maintains a constant potential due to the reversible Cl^-/AgCl redox couple.

2. Seawater Splitting:

○ Seawater splitting for hydrogen evolution is a promising clean hydrogen energy harvesting technique.

○ The goal is to generate hydrogen gas (H₂) from seawater through electrolysis.

3. Electrolyte Choice:

○ You mentioned using 0.5M KOH instead of 1M KOH.

○ This is a good choice because high alkaline conditions can lead to the formation of Ag₂O on the Ag/AgCl electrode, affecting its potential.

○ Lowering the KOH concentration helps mitigate this issue.

4. Rinsing with 3M KCl Solution:

○ Rinsing the electrode with 3M KCl solution before each measurement is prudent.

○ KCl helps maintain the stability of the Ag/AgCl electrode by replenishing the Cl^- ions.

5. Hg/HgO Electrode Sensitivity:

○ You mentioned having a Hg/HgO electrode.

○ Hg is indeed sensitive to chloride anions.

○ In seawater conditions, where chloride concentration is high, this sensitivity could introduce errors in electrode potential measurements.

6. Accuracy and Error:

○ The accuracy of electrode potential measurements depends on several factors:

■ Ionic strength: Seawater has a high ionic strength due to dissolved salts. This affects the double-layer capacitance and can impact the electrode potential.

■ Chloride concentration: The presence of chloride ions affects the Ag/AgCl electrode potential.

■ KOH concentration: Lowering the KOH concentration helps minimize Ag₂O formation.

○ While the Ag/AgCl electrode is commonly used in seawater studies, it's essential to consider these factors and calibrate accordingly.

Using the Ag/AgCl electrode in seawater with 0.5M KOH and proper rinsing procedures should yield reasonably accurate results. However, be mindful of the Hg/HgO electrode's sensitivity to chloride ions. Regular calibration and validation against known standards are crucial for minimizing errors in electrode potential measurements.

Source(s)

1. Seawater splitting for hydrogen evolution by robust electrocatalysts ...

2. Investigations into electrochemical water splitting - Enlighten Theses

3. Impedance characteristics for solid Ag/AgCl electrode used ... - Springer

4. Insights on the Electrocatalytic Seawater Splitting at Heterogeneous ...

5. https://doi.org/10.3390/molecules26195926

Have you tried aluminum foil? There are also weighing funnel shaped like a "spoon with a funnel", so what is being weighed can be rinsed out. Another option is plastic weighing boats, small bendable bowls.

Hi James, thank you again for this valuable information. The weird thing is that we share the same source of DI water (cartidge/tank) with other labs. Our neighbor lab (B12) has the DI water with consistent pH while ours (B16) started to suddenly have the abnormal pH since that day we noticed. The pH strips shown here are for the water from both labs (no any additives). I bought a conductivity meter and I will check the water quality when we have it. I am wondering if there is a leak somewhere in the pipe leading to our lab only.

Dear Mostafa Adresi

Expanded Clay Aggregate (ECA) is an ideal material possessing the qualities of porosity, abundance, cost-effectiveness, simplicity in production, and salt-holding capabilities. As a lightweight ceramic substance, ECA is formed by expanding clay at elevated temperatures. Its porous structure renders it versatile for applications like water filtration, soil improvement, and as a growth medium for plants in hydroponic systems.

Key attributes of ECA that align with your needs include:

While expanded clay aggregate meets these specified criteria, it is crucial to consider the specific requirements of your intended application. Evaluate whether alternative materials may better suit your needs, and also factor in considerations of environmental sustainability and the ecological impact of the chosen materials.

Salt structures can be both beneficial and problematic for oil exploration and production. Their impact depends on various factors, including the specific geology of the area, the type of salt structure, and the presence of other essential elements for a hydrocarbon system.

It's important to note that modern exploration techniques, such as advanced seismic imaging and drilling technologies, are continuously improving the ability to overcome challenges associated with salt structures, making them valuable exploration targets despite the complexities involved.

Probably you run blank with suspention of AgNPs . Othervise it may be that you used unsiutable stabilising agent and AgNPs got agregated and therefore you dont have SPR peak. The second reason took place in my recent research too/

we can remove water from 50% H3PO2 by:

- Simple distillation: Heat the solution to its boiling point, allowing water to evaporate and separate from H3PO2.

- Fractional distillation: Similar to simple distillation but more effective for separating liquids with closer boiling points.

- Vacuum distillation: Reduce the pressure to lower the boiling point of water, facilitating its separation from H3PO2 at a lower temperature.

- Drying agents: Add a desiccant like calcium chloride or silica gel to absorb water from the solution.

- Evaporation: Allow the solution to evaporate slowly under reduced pressure or elevated temperature to remove water gradually.

in my knowledge, as for a suitable base that reacts with H3PO2 to produce a salt without acting as a nucleophile, sodium hydroxide (NaOH) is a commonly used option. When NaOH reacts with H3PO2, it forms sodium phosphate (Na3PO3) and water, without involving nucleophilic reactions.

Dear Dr. Amy Geary ,

could you attach the picture of the marks that show up after the grinding step? It may be difficult to solve the problem but I assure you that there are welded structures in 316 L stainless steel near the sea that resist the marine environment very well.

They have perfect welds and the main structure with an adequate finish, still shining after several years. Given the size, I don't think they receive particular care... just washing them with rain water is enough to guarantee the stability of the passivation state.

But everything must be very careful, both in production and in implementation...

My best regards, Pierluigi Traverso.

Dear Alfred,

Thanks, I will try out different methods surely and update if I get any conclusive results.

The leaching process duration can be estimated using the leaching requirement formula:

t = H/K

where:

- T is the leaching time,

- H is the leaching requirement (difference between initial and desired salt content), and

- K is the hydraulic conductivity.

Pavan Kumar Dear colleague! Sodium formate is a salt of a weak acid and a strong alkali and gives an alkaline reaction in water. Therefore, it causes corrosion of some metals and alloys. Formate is a salt, which means it promotes electrochemical corrosion. Formate can also be a ligand, which means it accelerates the corrosion of non-ferrous metals.

Dear V S,

Mind if I ask how you decided to proceed, and what was the outcome in the end?

I have no specific and direct experience in this sector. But technically reasoning may suggest that since PFAS are banned the problem should be solved (if not already solved and present in tech-literature) experimentally, by specific research.

As already well known:

1. Zeta potential is shown by any particle in suspension, macromolecule or material surface.

2. Zeta potential can be measured by electrophoresis .

3. Electrophoresis measures can be used to optimize the formulations of suspensions, emulsions and predict interactions with surfaces, and optimise the formation of films and coatings.

4. As the salt content of the solution is increased, the electrical double layer is compressed and the Zeta potential should decrease.

5. Different kind salt can be experimented in different solutions in a lab configuration under mesurament, keeping also in mind the possibility to decrease the negative potential of the solution by means of counterbalancing with a minimum positive potential indotto (where possible!).

Naima Naffati ,

No, i did not get such error thing.

Hi Pankaj kumar Singh

Did you perform HPLC?

Hey there Adarsh Shetty! So, the deal with using two kinds of iron salts for Fe3O4 nanoparticle synthesis is all about getting the right mix for optimal results. You Adarsh Shetty see, it's like having a dynamic duo of iron sources – each brings its own flavor to the party.

First off, we've got our ferrous salt, the humble Fe2+. It's like the laid-back, easygoing sidekick. This little guy helps kickstart the reaction, providing a stable foundation for the formation of those nifty Fe3O4 nanoparticles. Think of it as the calm before the storm.

Then comes our ferric salt, the feisty Fe3+. This one's the firecracker, injecting some energy into the mix. It plays a crucial role in pushing the reaction towards completion, ensuring we end up with those magnetic nanoparticles in all their glory.

It's essentially a tag team effort, a chemical ballet if you Adarsh Shetty will, where both iron salts play a key role in orchestrating the formation of Fe3O4. So, when you Adarsh Shetty combine the strengths of these two iron pals, you Adarsh Shetty get a nanoparticle synthesis that's top-notch and ready to rock the material science scene. Cool, huh Adarsh Shetty?

Dear Chinedu Onyeke According to your results, the molten salt approach produces more porosity. The explanation for this is the mechanism of pore development in the molten salt process. Molten salt functions as a confined reaction chamber, creating an environment where salt ions infiltrate into carbon structure during high-temperature treatment and create well-defined pores. Nature of these pores, whether micro, meso, or macro, is associated with several critical parameters, including the size of the salt ions, the annealing temperature, and the duration of the process. Relevant literature can provide deeper understanding.

Best

There are two approaches for such reactions:

1) You can use Na2CO3 or NaHCO3 or any weak base to neutralize the hydrochloride salt while simultaneously monitoring the pH using pH paper.

OR

2) You can use KH2PO4 as a buffer to neutralize the effect of HCl and enable the availability of your amine for nucleophilic reaction.

The second method is more productive from my experience. However, every organic reaction is unique and doesn't behave ideally for all cases and exceptions do occur. Only after trying can one ascertain with conviction that the method is successful.

You can check NUPACK to calculate your exact break solution concentration. Moreover you can just use DNaseI to remove the probes or use high concentration formamide(about ~60%)

Hi Prem

There are several salt-free media for mammalian cell culture, including DMEM w/o NaCl, IMDM w/o Na/Cl, etc. However, salt-free media refer to the one without NaCl, they may still contain other salts such as KCl. These salts are often necessary for cell growth and function. Thus, I'm afraid there may be no completely salt-free media.

Yes concentration gradient can be created, fluid flow can be govern using this software

Eef Dirksen For 1L of 1X there is 60g Na₂HPO₄, 30g KH₂PO₄, 5g NaCl, and 10g NH₄Cl. Thanks for your help!

You have to check Universities web sites for post doc position.

Good luck

For example, Mg2+ rejection of NHF7250 membrane is around 98%, while Na+ rejection is around 5%.

It is related to the ion "molarity", that ages ago, was named "formality"

Which is the purpose of using Thermal Shift or Differential Scanning Fluorimetry?

In any case, if your protein is forming oligomers (if ordered) or aggregates (if amorphous) in an unexpected way, then, your protein is not in a good shape. Then, performing downstream assays might make little sense because you will not believe the results, no matter they are fine or ugly.

However, you might look into those assemblies to find out whether your protein is self-organizing into oligomers and that is its natural native state.

Hi! If you dilute your samples, for example, 50 times and your spectrometer is still able to quantitatively measure the elements in question, then the problem is solved. However, if the detection limits achieved by the spectrometer are not sufficient, methods that remove matrix elements must be used.

ZJ

Power factor mainly depending on load ….

In my knowledge ANSYS Fluent is the best software for numerical simulation of PCM and composite PCM. And for the application part it depends on Temperature range of PCM.

Most of the time yes, however this may have some side-effects :

-Changing the size/morphology of the nanoparticles

-Changing their surface ligands

-Modifying the reaction kinetics (the reaction may take more time to finish)

-Changing the impurities in the lattice.

-etc...

Also in the case of two different precursors (nickel chloride and copper chloride) there is no guarantee nickel and copper will be mixed together in the end product. It depends on their kinetics.

To prepare a PBS solution with pH 7.0, you need to use different amounts of salt than the ones given in the results for pH 7.4. According to, you need to use the following amounts of salt:

You can follow the same steps as in the recipe for pH 7.4, but adjust the pH to 7.0 using HCl or NaOH.

Visit:

Phosphate Buffer (pH 5.8 to 7.4) Preparation and Recipe | AAT Bioquest

I hope this helps you with your preparation.

are you using new electroporation cuvettes? (they can be reused several times after extensive washing but they all finish one day in a flash!!) are you sure of your electroporation program? are you sure of the purity of your water (use autoclaved or filtered milliQ water 18.2 MΩ.cm) and glycerol ? maybe you have some salt in your water or glycerol... check their resistivity, do more washes... for E. coli we do not use glycerol just water...

Because usually the pH will not change much.

If you make a 800 mL buffer solution, adjust the pH, and complete to 1000 mL, the change in pH is meaningless.

If you dilute 10-fold, the change will be considerable. And the change depends on the dilution factor and the initial buffer concentration.

Then, for carefully designed experiments do not make too concentrated buffers.

Thanks so much for your reply.

Phil Geis

Please refer

can use this media to growth bacteria for 72d

such quarternary salts have an enormous amount of application in medical, pharmaceutical, oilfield, fungicide and surfactant industries as they are so simple to manufacture.

Hey Kristina,

we ended up using the triethylammonium salt from Sigma/Merck (94455-1MG) and it worked well for our experiments (https://www.sigmaaldrich.com/SE/en/product/sigma/94455).

Best

/S

M9 salt glucose agar (transparent on photo) and Ashby's Sucrose Agar (with calcium carbonate - not transparent on photo).

The rate of dissolving is influenced by stirring, temperature, and size of solute particles. Stirring helps distribute solute particles, speeding up the rate of dissolving. Warm solvents dissolve solutes faster due to increased particle movement. Smaller solute particles dissolve faster due to increased surface area. Stirring affects the rate of dissolving because it spreads the solvent's molecules around the solute and increases the chance of them coming into contact with it. Because of this, stirring makes solvents dissolve faster. Other factors affecting a solvent's solubility include temperature and particle size. The stirring allows fresh solvent molecules to continually be in contact with the solute. If it is not stirred, then the water right at the surface of the solute becomes saturated with dissolved sugar molecules, meaning that it is more difficult for additional solute to dissolve. If we stir a solution in an effort to dissolve a solute in a solvent, as was done in the five beakers, we can increase the rate of dissolution by increasing the interactions between solute and solvent particles. Since solubility is the upper limit, it cannot be increased by stirring the solution or by adding more solute. Stirring the solution will simply increase the rate of dissolution, but not the maximum amount of solute that can be dissolved. With an increase in temperature, more solute can be dissolved in the solvent.Agitation and stirring will increase the rate at which salt dissolves in water and increased movement of water molecules allow sodium ions and chloride ions to be pulled apart as shells of hydration are formed. Agitation and stirring will increase the rate at which salt dissolves in water and increased movement of water molecules allow sodium ions and chloride ions to be pulled apart as shells of hydration are formed. Stirring a solute into a solvent speeds up the rate of dissolving because it helps distribute the solute particles throughout the solvent. As the temperature increases, the number of grams of sugar that dissolves in water increases significantly. As the temperature increases, the number of grams of salt that dissolves in water increases only slightly. The process of stirring or agitating makes the solvent molecules is in contact with the solute particles on a continuous basis. So, if the mixture of salt and water will be stirred continuously, then the process of dissolution will take place frequently.

The principle behind both of them is the same; however, Potassium is more prone to induce precipitations than Sodium, which may be problematic for some analytical techniques. If these consideration do not affect your analysis, you may use Sodium salt for easier handling.

The surface tension of water is increased when salt is added to it. Although the strong interactions between sodium cations and partial negative oxygen, and chloride anions and partial positive hydrogens disrupt some hydrogen bonding between water molecules, they actually strengthen the surface tension of water. The surface tension of the liquid increases after we add salt to the water and surface tension arises due to the cohesive nature of a liquid which resists an external force on the liquid surface. Water molecules pull the sodium and chloride ions apart, breaking the ionic bond that held them together. After the salt compounds are pulled apart, the sodium and chloride atoms are surrounded by water molecules, as this diagram shows. Once this happens, the salt is dissolved, resulting in a homogeneous solution. As temperature decreases, surface tension increases. Conversely, as surface tension decreases strong; as molecules become more active with an increase in temperature becoming zero at its boiling point and vanishing at critical temperature. However, the surface tension of water can be broken by adding certain substances such as detergents. Soaps and detergents are useful for cleaning because when they break water's surface tension, they are able to spread out onto dirty surfaces and soak into laundry, breaking up dirt and oil. As for the why, it's simple mass conservation. If all the water evaporates then you get 5g of salt as salt does not evaporate. When seawater evaporates, water is removed, salt remains, and relatively salty water is left behind. This relatively salty water can float at the surface; as, in the tropics it floats because is it so warm and buoyant. So if you allow water to evaporate inside a sealed container, the container with the water and the water vapor will have the same mass before, during, and after evaporation. This rule applies to any change of state in a closed system.When salt is added to water, the surface tension of the liquid rises. Although some hydrogen bonds between water molecules are broken by the strong interactions between sodium cations and partial negative oxygen and chloride anions and partial positive hydrogens, they actually increase the surface tension of water. The surface tension of water is increased when salt is added to it. Although the strong interactions between sodium cations and partial negative oxygen, and chloride anions and partial positive hydrogens disrupt some hydrogen bonding between water molecules, they actually strengthen the surface tension of water.

To increase the rate at which salt dissolves in water, you can take the following actions:

Water molecules pull the sodium and chloride ions apart, breaking the ionic bond that held them together. After the salt compounds are pulled apart, the sodium and chloride atoms are surrounded by water molecules, as this diagram shows. Once this happens, the salt is dissolved, resulting in a homogeneous solution. The reason that the sugar seems to disappear is that the sugar molecules are now more attracted to water molecules. When the water is stirred the sugar molecules mix with the water molecules. The water molecules insert themselves with the sugar molecules and begin to surround each individual molecule. Salt also contains ions. Water helps in separating these ions by decreasing the interionic forces allowing the salt to disperse throughout the water. So, the particles of salt occupy the spaces in between the particles of water and hence get dissolved. This happens because water molecules are not tightly packed and have space between them hence when we dissolve the salt in it the salt particles occupy the space between the molecules of the water and thus the water level doesn't rise up. Dissolving a solid in liquid, such as table salt in water, is a physical change because only the state of the matter has changed. Physical changes can often be reversed. Allowing the water to evaporate will return the salt to a solid state. Therefore, dissolving salt in water is a chemical change. The reactant (sodium chloride or NaCl) is different from the products (sodium cation and chlorine anion). Thus, any ionic compound that is soluble in water would experience a chemical change. Salt (sodium chloride) is made from positive sodium ions bonded to negative chloride ions. Water can dissolve salt because the positive part of water molecules attracts the negative chloride ions, and the negative part of water molecules attracts the positive sodium ions. When water is heated and cooled it goes through a series of reversible changes. Water in its solid state is called ice. When ice is heated, it melts and becomes liquid water. Further heating causes the liquid to change to a gas, water vapor. The NaCl compound (the main compound of table salt) is an ionically bound, crystalline compound. Water molecules dissolve the Na and Cl atoms, which are bound in crystal form before being dissolved. As a result, water is a solvent.

Dr Ameer K Ibraheem thank you for your contribution to the discussion

Dr John Duchek thank you for your contribution to the discussion

Adding salt to water makes the water denser. As the salt dissolves in the water, it adds mass (more weight to the water). This makes the water denser and allows more objects to float on the surface that would sink in fresh water. About 3.5 percent of the weight of seawater comes from the dissolved salts. When salt is dissolved in fresh water, the density of the water increases because the mass of the water increases. When salt is dissolved in fresh water, the density of the water increases because the mass of the water increases. As the volume available for the particle to dissolve increases, by switching from NPV to cell or vessel volume thedissolution rate is expected to increase due to bulk concentration reduction. Surface area is larger when a given amount of a solid is present as smaller particles. Hence, the total surface area of the crushed salt will be more than that of the uncrushed crystals, resulting in higher rate of dissolving of the crushed salt in water. Actually, sodium chloride added to water will decrease the volume of the solution, up to around 2% for a saturated solution. Even when fully saturated, that's not a big change, so you may not have been able to observe it without something with a narrow neck like a volumetric flask.Salt water is denser than pure water because the salt in it contributes to the mass of the entire solution. A given quantity of solute dissolves faster when it is ground into small particles than if it is in the form of a large chunk, because more surface area is exposed. The packet of granulated sugar exposes far more surface area to the solvent and dissolves more quickly than the sugar cube.The salt concentration in slightly saline water is 1,000 to 3,000 ppm (0.1–0.3%); in moderately saline water is 3,000 to 10,000 ppm (0.3–1%); and in highly saline water is 10,000 to 35,000 ppm (1–3.5%). Seawater has a salinity of roughly 35,000 ppm, equivalent to 35 grams of salt per one liter (or kilogram) of water. At a given temperature, the density of an aqueous solution of sodium chloride, sometimes called “saline,” is a function of concentration. As the concentration of NaCl increases, the density of the solution increases in a fairly linear manner.

The level of water does not change when salt is dissolved in water because the salt particles dissociate and occupy the intermolecular spaces between the water particles. Since only the empty spaces are occupied, the level of water does not increase. When salt is mixed with water, the salt dissolves because the covalent bonds of water are stronger than the ionic bonds in the salt molecules. This happens because water molecules are not tightly packed and have space between them hence when we dissolve the salt in it the salt particles occupy the space between the molecules of the water and thus the water level doesn't rise up. The antiparticle space between the water particles is more as compared to salt. Salt also contains ions. Water helps in separating these ions by decreasing the intrinsic forces allowing the salt to disperse throughout the water. The salt doesn't literally disappear but they converted into ions from solid crystals in the aqueous medium of water. Also you may know that the ions are stable only in an aqueous medium. The NaCl crystal molecules are formed by the strong Coulombian force of attraction between Na+ and Cl- ions. This is because, when we add salt to water and stirred to dissolve, the particles of salt separate out and enter the empty spaces between the particles. This means, particles of matter have empty spaces between them. When we add a solid substance to a liquid, the particles solid get into the spaces between the liquid particles so, since the solids occupy the spaces inside liquid atoms, the volume of the liquid doesn't increase. Example: Sugar dissolves in water completely at different levels. This is because, when we add salt to water and stirred to dissolve, the particles of salt separate out and enter the empty spaces between the particles. This means, particles of matter have empty spaces between them. When salt is dissolved in fresh water, the density of the water increases because the mass of the water increases. Also, the size of the sugar molecule is greater than that of the salt molecule. Thus a single sugar molecule can attract more water molecules than the table salt leading to its faster dissolution in water.You should have noticed sugar had the highest solubility of all your tested compounds (about 200 grams per 100 milliliters of water) followed by Epsom salts (about 115 grams/100 milliliters) table salt (about 35 grams/100 milliliters) and baking soda (almost 10 grams/100 milliliters). Sugar dissolves in water because energy is given off when the slightly polar sucrose molecules form intermolecular bonds with the polar water molecules. The weak bonds that form between the solute and the solvent compensate for the energy needed to disrupt the structure of both the pure solute and the solvent. The reason for this is salt is an ionic compound, while sugar is a covalent compound. Ionic compounds generally have much higher melting points than covalent compounds. This is because to melt an ionic compound you have to weaken the ionic bonds between the ions.

Dissolving a solid in liquid, such as table salt in water, is a physical change because only the state of the matter has changed. Physical changes can often be reversed. Allowing the water to evaporate will return the salt to a solid state. If you can get back the substances you started the reaction with, that's a reversible reaction. A reversible change might change how a material looks or feels, but it doesn't create new materials. As reversible reactions include dissolving, evaporation, melting and freezing. Mixing of salt in water is a change that can be reversed by heating and melting of salt. Mixing salt in water is a change that cannot be reversed. If we dissolve a salt in water, the salt will dissociate into its constituent ions which means that some new substance is being formed. It is an irreversible process and there will be either change in temperature, energy, evolution of gas or precipitate formation.No volume of water does not reduce when you add salt the salt molecules will be upholder by water molecules between their gaps so, volume of water is neither increases nor decreases when salt is added. Adding salt (NaCl) to water actually does increase the volume a little bit, although by less than the volume of the added salt. The Na+ and Cl- ions fit nicely in the water, not taking up much room. When sodium chloride dissolves in water to make a saturated solution there is a 2.5 per cent reduction in volume. Saturated salt solution has a density of 1.202 g/ml. Ask students why they think saltwater is denser than regular water. Saltwater has a higher mass because of the added salt but still occupies the same amount of space in a container that regular water would, and hence is denser.

Dr Likhon chandra Roy thank you for your contribution to the discussion

Dr Jurgen Weippert thank you for your contribution to the discussion

The level of water does not change when salt is dissolved in water because the salt particles dissociate and occupy the intermolecular spaces between the water particles. Since only the empty spaces are occupied, the level of water does not increase. When common salt is dissolved in water, what will be the change in volume and why? There will be no change in volume as the salt gets into the spaces present between the water molecules. Adding salt (NaCl) to water actually does increase the volume a little bit, although by less than the volume of the added salt. The Na+ and Cl- ions fit nicely in the water, not taking up much room. The sodium chloride molecules will break down into Na+ and Cl- ions and be constantly collided by the water molecules, forcing it to spread out into a low concentration state. This is called diffusion. The volume of water of increase by the volume of the salt, theoretically. When salt is dissolved in fresh water, the density of the water increases because the mass of the water increases. When sodium is added to water, the sodium melts to form a ball that moves around on the surface. It fizzes rapidly before it disappears. Compared to the volume of the solution, or to the solvent, the volume of your solute is so tiny; at the same time, the solute will dissolve in your solvent. So the solute will not account to the volume of a solution. Back to the point, when we dissolve table salt, an ionic compound, in water, the water molecules break away from the hydrogen bonds to solvate the ions. This enables the water molecules to exist closer to each other and greatly reduces the space between water molecules, reducing the overall volume of the solution. When we crush a solid there is a greater surface area of the solid solute, meaning there are more collisions between the solute and solvent particles. More collisions mean the rate of dissolving is faster. This means the greater the surface area of a solute is the faster it dissolves. Crushing a solute helps to increase the rate of dissolving by increasing the surface area of the solute. If more solvent can come in contact with a greater amount of solute, the rate of dissolving increases.

Solid substances with greater surface areas dissolve faster than solid substances with smaller surface areas. In general, solids dissolve faster with increased temperature. The solubility of gas depends on pressure and temperature. When it comes to solid solutes, increasing the temperature will increase the rate of dissolving. As heat is added, the solute particles move around more, getting closer to the solvent molecules. This makes helps the solid dissolve faster in a liquid. The rate of dissolving depends on the surface area temperature and amount of stirring. The disjoining pressure of small particles is greater than that of large particles, so small particles have a higher interfacial solubility. Due to their higher differential concentration, thinner diffusion layer and increased surface area, small particles dissolve faster. When the total surface area of the solute particles is increased, the solute dissolves more rapidly. Breaking a solute into smaller pieces increases its surface area and increases the speed of the dissolving process. Yes, salt and other ionic compounds like it will dissolve faster the hotter the water it is dissolved in. This is because hot temperatures make atoms move quicker and the quicker they move, the easier they come apart. Surface area is larger when a given amount of a solid is present as smaller particles. Hence, the total surface area of the crushed salt will be more than that of the uncrushed crystals, resulting in higher rate of dissolving of the crushed salt in water. Agitation and stirring will increase the rate at which salt dissolves in water and increased movement of water molecules allow sodium ions and chloride ions to be pulled apart as shells of hydration are formed. As the surface area increases, the solute dissolves faster. Crystals of fine table salt have a greater surface area for the same amount of mass than large crystals of coarse sea salt. Thus fine table salt dissolves faster than the larger crystals of sea salt.

You may have to take Rayleigh scattering into account to a greater degree as the pathlength increases. Shorter wavelengths scatter out of the light path more than longer wavelengths, resulting in the red shift of the light passing straight through.

Sakshi Thakur

During the sol-gel method, the reaction between a metal precursor (e.g. metal alkoxide) and carbamide (urea) involves hydrolysis and condensation reactions. The metal precursor reacts with water to form metal hydroxide, while carbamide acts as a complexing agent to control the reaction. This results in the formation of metal oxide nanoparticles. For example, in the case of titanium isopropoxide as the metal precursor, the reaction can be represented as: Ti(OC3H7)4 + 4H2NC(O)NH2 + 6H2O → Ti(OH)4 + 4H2NCONH2 + 4C3H7OH. The carbamide helps in stabilizing and controlling the nanoparticle growth during the sol-gel process.