Questions tagged [solutions]

This tag should be applied to questions dealing with solutions of any kind. A solution is a liquid or solid phase containing more than one substance where, for convenience, one (or more) substance(s) called the solvent is treated differently from the other substances, which are called solutes. If water is the solvent, then the more appropriate 'aqueous-solution' tag should (also) be specified.

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1answer
18 views

Difference between a species and a phase in a solution?

Overview: As of my knowledge from metallurgical thermodynamics a phase is a thermodynamically stable and homogeneous entity made up of different species of a given concentration. e.g = 'Austenite' ...
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0answers
12 views

Why does changing the salt of the salt bridge (group 1 chlorine salts) effect the voltage produced in a galvanic cell?

My experiments results showed that the voltage decreases down Group 1 chlorine salts in the salt bridge. All other variables were kept constant. Zinc and Copper rods were used. Concentrations of the ...
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0answers
16 views

How is “dry water” made with fumed silica? [closed]

My daughter wants to make “dry water” from fumed silica for her science fair. None of the information we’ve found gives the exact ratio to use. Our reading was 5% fumed silica by weight. I tried to ...
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3answers
9k views

Does solute add to volume of solution?

I have to calculate the concentration of sucrose in water just by knowing their masses (and their temperature). Now, if the volume doesn't change when the sugar is being dissolved, I can do that quite ...
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2answers
86 views

Will NaF + CaCO3 precipitate much CaF2?

If I mix sodium fluoride, calcium carbonate powder, and water, under what conditions (if any) would there be an equilibrium? I.e. assume we start out with fully dissociated $\ce{Na+(aq) + F-(aq)}$, ...
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2answers
479 views

Why does freezing point decrease when vapour pressure decreases in dilute solutions?

I was studying colligative properties of dilute solutions, and one of the properties was freezing point depression. The confusion I had was that, if vapour pressure decreases, it should be easier to ...
6
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1answer
233 views

Apparent contradiction in the type of deviation of an ethanol-water mixture

For a mixture of $\ce{EtOH}$ and $\ce{H2O}$: $\Delta H_{\text{mix}} < 0$ (exothermic) and $\Delta V_{\text{mix}} < 0$ (volume contraction). This means that the unlike interactions are stronger ...
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0answers
15 views

What solvent and stabilizer should be used to to prepare gallium oxide from gallium nitrate hexahydrate precursor? [closed]

I have been trying to prepare gallium oxide from gallium nitrate hexahydrate precursor. But I am unable to get a clear homogenous solution. Is there some method to prepare gallium oxide from gallium ...
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0answers
20 views

Can Methylene Blue Detect Spoilage in Food?

Initially, there is already a product which is a sensor based on Methylene Blue, which can detect changes in oxygen levels in a packaging. However, as our thesis project, we decided to take on this ...
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0answers
10 views

Is Raoults Law valid if the solute is non volatile but have less vapour pressure than pure solvent?

We know that on adding a non-volatile solute to a pure solvent its vapour pressure increases because of the reluctance of solute to evaporate(i.e. strong intermolecular forces of attraction) Instead ...
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1answer
31 views

Is the solution isotonic, hypertonic, or hypotonic?

The problem is shown below. I don't understand how can the tonicity of a solution be determined if the solution has multiple solutes dissolved in it. Do I take the total sum of the mass of solutes ...
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1answer
49 views

Effect of impurities on Enthalpy of vapourization

How does the Enthalpy of vapourization change when impurities are added? I know that the boiling point of a substance increases on addition of impurities, but how does the Enthalpy of vapourization ...
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2answers
74 views

Can you dissolve iodine without potassium iodide? [closed]

I don't have a sufficient amount of potassium iodide, so I wanted to know if there is other way which I can use to dissolve iodine without using potassium iodide.
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1answer
162 views

Why zinc sulphate solubility is higher in ethylene glycol than water?

I'm trying to find saturation point for dissolved zinc sulphate in water and ethylene glycol. Based on my knowledge, water is more polar than ethylene glycol as reflected in its higher dielectric ...
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0answers
29 views

Derivation of freezing-point depression equation

Can anyone provide me the real derivation of depression in freezing point? In almost all of the books and online articles that I have read, it says $\Delta T_\mathrm{f}$ is directly proportional to ...
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1answer
46 views

Can ascorbic acid be neutralized and keep it's elastic properties in dough?

Ascorbic acid (C6H8O6) is commonly used in dough to give it strength and elasticity. However, I need this dough to be alkaline, or at the very least neutral. I've used sodium carbonate (Na2CO3) before ...
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1answer
20 views

How is Henry's constant affected by change in temperature

According to me Henry's constant $K_h$ should be directly proportional to the effect of temperature. It is because $K_h$ is inversely proportional to solubility and as we increase temperature ...
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2answers
187 views

Is there a potentiometric method for monitoring salt formation in organic solvent?

I work in a pharmaceutical R+D lab, and currently aim to develop a validatable potentiometric method for determining the optimal amount of acid to add to a basified small organic molecule for ...
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2answers
37 views

How would I separate a solution of sodium iodide and water in order to obtain the sodium [closed]

I am an amateur in this field of science and I am trying to separate a solution of Sodium Iodide and water. How would I separate the solution so I can obtain sodium?
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0answers
25 views

Ion exchange resins

My problem is explained quite easily: I have no experience with ion exchange resins but I would like to test something out in order to exchange my sulfate ions in solution for nitrate (can also be ...
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1answer
535 views

What is the logic behind the division into groups of anions and cations in qualitative inorganic analysis? [closed]

I find it very confusing and hard to memorize. Is there a way to deduce it, like understanding how it is derived, or is it just one of a lot of ways you can do it but is the standard one? Do people ...
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1answer
467 views

Equation to find specific gravity (or density) from a solution of sugar and water

Is there an equation or simple way to calculate the final density of a solution made from x grams of sugar and y liters of water? And would it work in reverse? if we have y liters of water at z ...
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1answer
53 views

Is there any non-toxic and non-solvable-in-air liquid? [closed]

I want to heat the air with non-aqueous, non-toxic and non-solvable-in-air liquid (with very low relative pressure in air). Is there any such liquid exists? It would be great if the boiling point of ...
2
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1answer
286 views

Kohlrausch Law and conductivity

Im writing up a lab report at the minute and part of it concerns ions in solution and how they affect conductivity. I've been doing lots of reading and I think ive got the grasp of most of it, but its ...
2
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1answer
43 views

Methods to increase the speed of dissolving potassium sulfate in water apart from heating, grinding or shaking

I bought potassium sulfate to be used as a fertilizer. The fertilizer comes in the form of small pebbles 1-2mm in diameter. Wikipedia states that the solubility is around 111g/liter at 20°C. I ...
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1answer
45 views

If volatility depends on intermolecular forces, then why in Raoult's law, two substances have different volatility?

I have a doubt, Ideal solutions are solutions where intermolecular forces between solute-solute and solvent-solvent are nearly equal to solute-solvent. Since intermolecular forces between A-A = B-B, ...
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0answers
28 views

Is it possible to remove sugar from a sweetened drink but without boiling it? [duplicate]

Is it possible to remove sugar from a sweetened drink without boiling it? This might not be a good question but I'm wondering if you could separate sugar from a sweetened drink and replace the sugar ...
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1answer
3k views

What actually happens when citric acid is added to a highly alkaline soap solution?

A few days ago I made an experiment. I diluted a few small chunks of bar soap with 20 ml of water. I then measured the ph of the solution which was around 10. I then added a tiny amount of citric acid....
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1answer
29 views

What formula allows adjusting balance of (Ethyl Alcohol / Water / Caffeine powder) to know concentration for the Caffeine solution?

I am experimenting with different levels of concentrated caffeine solution. The solution has a small percentage of ethyl alcohol, in the $\ce{H2O}$. Problems encountered too much ethyl alcohol ...
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1answer
103 views

Cheap but efficient disinfectant / biocide for home lab

EDIT I am forced to reword my question about a chemical mixing ratio. I have seen in Wikipedia that peroxide ($\ce{H2O2}$) and Acetic Acid can be mixed to Peracetic acid - this is an equilibrium. I ...
3
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2answers
645 views

Mixing of powders to make stock solutions

For a solution such as: Luria-Bertani (LB) Broth: 10 g tryptone 5 g yeast extract 10 g of NaCl ($M = 58.44\ \mathrm{g/mol}$) q.s. to 1 l, pH to 7.2, autoclave. I would like to make a bulk amount ...
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1answer
2k views

How to determine the empirical formula given mass percentages of the elements and the molecular weight?

A compound has $67.3 \% \rm~C,4.62 \%~N,6.93 \%~ H$ and O. Determine the molecular formula of the compound knowing its molar mass is $283\rm~\frac{g}{mol}$. My solution : The percentage for the ...
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3answers
107 views

Dynamic equilibrium in unsaturated solutions

One standard definition of equilibrium in beginner chemistry is that for a reversible reaction, (dynamic) equilibrium has been achieved when the rate of the forward and backward reactions are equal. ...
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1answer
53 views

Can compounds dissolved in different miscible solvents react?

For example, can crystal iodine dissolved in ethanol react with sodium thiosulfate dissolved in water when mixed together?
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1answer
61 views

Is it possible to prepare a 0.1 N solution of HCl and methanol? [closed]

In my lab guide I read: "Use a $\pu{0.1 N}$ solution of methanol-chloridic acid $(9:1)$ for the anthocyanin extraction", so I tried to calculate the volume of $\ce{CH3OH}$ and $\ce{HCl}$ to prepare it,...
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1answer
26 views

Can there be a compound which stops the pesticide from entering into the fruit or vegetable? [closed]

Can there be a compound which stops the pesticide from entering into the fruit or vegetable? For example, a solution which is sprayed before pesticides and somehow blocks pesticides from entering into ...
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1answer
10k views

Why do non-polar covalent compounds dissolve in non-polar covalent compounds only?

My textbook says that electrovalent and polar covalent compounds dissolve in electrovalent compounds and polar covalent compounds but not in non-polar covalent compounds. I understand the reason for ...
3
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1answer
462 views

Properties of azeotropes

Consider two liquids with vapour pressures in pure form being ${P^o}_A$ and ${P^o}_B$. ${P^o}_B >{P^o}_A$ which implies liquid B is more volatile. If the liquids formed an ideal solution, then a ...
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2answers
101 views

Freezing Point Depression and Temperature Decrease

I don't have a problem understanding the chemical mechanisms underlying freezing point depression or colligative properties in general, but what I cannot seem to grasp is how if you add salt to ice ...
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2answers
7k views

Why does shampoo lather much more the second time it is applied?

When I shampoo my dirty hair, the first time it does not lather very much. The second time it lathers a lot. Why is this?
3
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1answer
2k views

Acidic and alkaline salt solutions: why do some salt form acid/bases while others don't [closed]

I have a question regarding salts and their solutions. How come some salts, like sodium carbonate and ammonium chloride, produce acids/bases when dissolved in water? Moreover, how can you predict ...
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0answers
18 views

How can I make a reference humidity environment with NaOH pellets? [duplicate]

I have NaOH pellets at my disposal. Some of the pellets are degraded, but most are not, and I can provide a new batch if needed. I would like to test several humidity sensors in an environment with a ...
0
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1answer
68 views

Difference of Ascorbic acid dissolved or precipitated in Glycerol?

Difference of Ascorbic acid (AA) dissolved or precipitated in Glycerol? Referring to pat US20110008445A1 Solution 1 At 25C, AA was dissolved in glycerol and alcohol (subsequently removed by ...
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2answers
178 views

Thickening and/or slowing evaporation of IPA-based ink

The conundrum I have a security printing ink that I make by adding an IR-absorbing dye to a 50/50 mix of Isopropyl Alcohol and distilled water. The ink solution is pale green but dries virtually ...
2
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1answer
62 views

What is the interaction between dissolved ions of opposite valence in a solution at rest?

NaCl is dissolved in water. Ions sodium and chloride are sufficiently free from each other so that they may occupy different regions of the solution after an active transport process through a ...
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2answers
353 views

Phenolphthalein Indicator mixed with base that first turns pink and then clear

What occurs in the following situation: After adding 2 drops of Phenolphthalein Indicator (an indicator that turns bases pink and stays clear for acids,) into a unknown solution, the solution turns ...
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2answers
479 views

Volume change in positive deviation from Raoult's Law

Let us take a mixture of ethanol and acetone as an example. When ethanol is mixed with acetone, the hydrogen bonding between ethanol molecules gets disturbed as actone molecules get in between the ...
0
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1answer
89 views

Finding original concentration w%/w%

A question from a grade 9 admission exam: When 1 kg of salt is added to a solution of salt and water, the solution becomes 33 1/3% salt by mass. When 1 kg of water is added to the new solution, the ...
4
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1answer
422 views

Why does concentration of solutions of alkali metals in liquid ammonia change the magnetic properties?

In "NCERT Chemistry for Class XI - Volume II", in chapter "s-block elements", under the topic "Chemical Properties of alkali metals", it is given: (vi) Solutions in liquid ammonia: The alkali ...
9
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1answer
2k views

Vapor pressure of immiscible liquids

I have read that vapour pressure of a mixture of two immiscible liquids is $$P=P^0_A + P^0_B$$ where A and B are immiscible liquids. If they are immiscible, they would form separate layers. Thus ...