Questions tagged [homework]

DEPRECATED. DON'T USE THIS TAG.

Filter by
Sorted by
Tagged with
-2
votes
0answers
36 views

Chemical reaction of cornstarch and shampoo [closed]

My class have a science experiment and they ask me what will happen if i mixed cornstarch and shampoo and what are the chemical reaction between them. If they mixed together what is the chemical ...
0
votes
2answers
20k views

How does the polarity of the eluent and sample affect the Rf value in thin layer chromatography?

A three-component mixture (X, Y, Z) was separated using normal phase TLC. Three eluents of varying polarity were used. Select the TLC plate that was developed using the least polar eluent (click on ...
0
votes
1answer
2k views

Osmotic pressure of a solution of a protein?

A small protein molecule, code-named "sloth", has a MM of $\mathrm{1.50 x 10^4}$ g/mol. What is the osmotic pressure exerted at $\mathrm{24.0^oC}$ by 25.0 mL of an aqueous solution that contains $\...
0
votes
1answer
727 views

Simple Distillation of Unknowns

Can an identification experiment (using acetonitrile, isopropyl, and cyclohexane) using simple distillation and boiling point be improved by using a digital thermometer? Can simple distillation be ...
0
votes
1answer
4k views

Unit conversion of Molar Conductivity

I know this might be a silly question but I am confused with different answers of internet. My question is: Molar conductivity is given as: Molar conductivity = $\frac{\kappa}{M}$. S.I. unit of : $...
0
votes
2answers
4k views

What happens to acids/bases left out overnight?

I conducted a titration experiment a few days back and was unable to neutralize the solution in time, so I had to leave the solutions of HCl and NaOH out overnight in order to use them the next day. ...
0
votes
2answers
8k views

Why and how carboxylate ion has greater stability than carboxylic acid?

I found it written in my textbook. I think it's a misprint, I can't think of any logic behind this statement. I've only learned that ion is less stable specie so carboxylate ion cannot be more stable ...
0
votes
1answer
444 views

Stability order of octahydrobiphenylenes

I am facing trouble in the following question What is the stability order of the following compounds? In my view cis is less stable than trans. So if prior groups are on the same side of the ...
0
votes
1answer
121 views

Arranging different oxygen-containing organic compounds by decreasing acidity

I am facing difficulty in the following problem. Arrange the following compound in decreasing order of acidity. It is clear that conjugate base of (Q) is more stable.hence it is most acidic.in R) ...
0
votes
2answers
1k views

When finding hybridisation of atoms, why are double bonds and triple bonds only considered once?

To figure out what hybridization an atom has is to just count the number of atoms bonded to it and the number of lone pairs. Double and triple bonds still count as being only bonded to one atom. (...
0
votes
2answers
44k views

How to determine which aqueous solution has the largest freezing point depression

Question This is more of a conceptual question. Let's say that we are given different aqueous solutions and we are asked to choose the one with the highest freezing point depression, which do we ...
0
votes
2answers
1k views

How can I derive whether the methyl cation or anion is planar?

According to VSEPR theory, in which species do all the atoms lie in the same plane? $\ce{CH3+}$ $\ce{CH3-}$ (A) 1 only (B) 2 only (C) both 1 and 2 (D) neither 1 nor 2 My try: ...
-1
votes
1answer
1k views

Finding the molarity of an acid in a titration

I was doing a question that asks the molarity of a 10 mL of tartaric acid that is titrated to phenolphthalein endpoint with 20 mL of 1.0 M NaOH. I worked it out by equating the molarity of the NaOH ...
0
votes
1answer
154 views

Fe/Ga cell has a negative potential?

In the following homework problem, the answer says: "$E ^{o}_{cell}$ is negative, which makes the $\ce{Fe}$ and $\ce{Ga}$ half-reactions non-spontaneous." But I found $E ^{o}_{cell}$ to be positive ...
0
votes
1answer
2k views

When an expansion of a system does work on its surroundings, is the sign for work negative?

This question comes to me from trying to explain the answer $1.67\ \mathrm{L}$ of this question: A cylinder with a moving piston expands from an initial volume of $0.250\ \mathrm{L}$ against an ...
0
votes
2answers
117 views

If PQ, T2U2, RS2 and VW4 have the same Ksp, which has the lowest solubility in moles of solute per litre?

If the solubility products of the following ionic compounds all have the same numerical value, and all solubilities have values between zero and one, which one would have the lowest solubility in ...
0
votes
3answers
6k views

Basicity of substituted pyridines

Which of the following pyridines are most basic? I would've considered D, since chlorine is the most electronegative, and would therefore have the largest partial negative charge, making it more ...
0
votes
1answer
5k views

How to calculate the pH of a propanoate buffer after addition of sodium hydroxide?

I've calculated the pH of the buffer solution, as seen. The question I'm referring to is part d), which asks: 'Calculate the pH of the solution after 0.01 mols of NaOH are added to 500$cm^3$ of the ...
0
votes
1answer
233 views

Attack at ketone vs carboxylic acid carbonyls

Why in this the nonbonding electrons of N group does not attack C2 as I think it is more electropositive ? Then how pyruvic acid is converted to alanine.
0
votes
1answer
59 views

How would you go about solving this pH problem?

What is the $\mathrm{pH}$ of a $0.24\ \mathrm M$ solution of benzylammonium chloride ($\ce{C6H5CH2NH3Cl}$)? $K_\mathrm b$ for benzylamine is $2.2\times10^{-5}$ Your answer must be within $\pm 0.4\ ...
0
votes
1answer
4k views

How do I arrive at the mass of solvent from a molar fraction concentration?

So the question says: If the mole fraction for $\ce{H2SO4}$ in an aqueous solution is $0.325$, what is the mass of water (in grams) in $100\ \mathrm{mL}$ of solution? Me, and my other classmates ...
0
votes
1answer
15k views

When Z>1 are repulsive forces dominant or are attractive forces dominant?

According to PVreal = ZRT If z >1 repulsive forces are dominant or are attractive forces? Different teachers are telling contradictory answers and after referring a few books, I have become more ...
0
votes
1answer
2k views

Predicting the solution with the highest boiling point

I am facing problem with the following question: Predict which solution will have the highest boiling point in increasing order? $1~\%$ solution of $\ce{C6H12O6}$ $1~\%$ solution of $\ce{NaCl}$ $1~...
0
votes
1answer
84 views

working with ratios and RMS to find variables

question consider separate 1.0L samples of helium and $UF_6$ both at 1.00atm and containing the same number of moles. what will the ratio of the separate temperature need to be in order to have the ...
0
votes
1answer
4k views

How to find the rate of effusion given rates?

Question At $25~^\circ\mathrm{C}$, a sample of $\ce{NH}$ effuses at the rate of $0.050$ moles per minute. Under the same conditions, what is the molar mass of a gas that effuses at approximately one ...
0
votes
1answer
4k views

The mass of a carbon-12 atom is 12 amu. What percent of the mass is located in the nucleus?

The mass of a carbon-12 atom is 12 amu. What percent of the mass is located in the nucleus? and Why is the value so close to 100%?
0
votes
1answer
2k views

Amount of Cl- needed to precipitate AgCl given Ksp and [Ag+]

Why is $0.25 \ \mathrm{mL}$ the correct answer in this problem? I used the Ksp to find the molarity of Chlorine to be $3.47 \times 10^{-2} \ \mathrm{M}$. Then I used the formula $$\text{Molarity}_{...
0
votes
2answers
323 views

What type of reactions are used in this synthesis?

The compound $\ce{(CH3)2CHCH2NH2}$ can be synthesised by the following route. $$\ce{CH3CH=CH2 ->[1] CH3CHBrCH3 ->[2] (CH3)2CHCN ->[3] (CH3)2CHCH2NH2}$$ What types of reaction are used in ...
0
votes
1answer
5k views

How to round correctly when calculating the average and standard deviation?

Is my Chemistry book wrong on the significant figures in this exercise? Why did they round to 0.16 instead of 0.1580 ? Also why did they round down the means?
0
votes
1answer
4k views

How to make copper plating solution?

I intend to make the following composition of copper plating solution: \begin{array}{c:c} \rm material & \rm concentration \\\hline \rm Copper sulfate & \pu{200 \frac{g}{L}} \\ \rm ...
0
votes
1answer
526 views

How to make by dilution a certain ion concentration

The question I'm trying to answer is this: What volume of $0.25\ \mathrm{mol/l}$ calcium nitrate is required to make by dilution with water $500\ \mathrm{cm^3}$ of a solution with a nitrate ion ...
0
votes
1answer
3k views

How do we count charges in this example of a Redox reaction equation?

My brother(younger) had a doubt regarding this chemistry book example so I let him here : Question : Balance the equation : $\ce{H+ + MnO4- + Fe^2+ -> Fe^3+ + Mn^2+}$ Solution steps(as given by ...
0
votes
1answer
261 views

Determination of initial excited state via luminescence

A one electron species initially in the some excited state ($n_i$) is irradiated with a light of wavelength 121 nm when the electron is promoted to a further higher orbit ($n_f$). In ...
0
votes
2answers
80 views

What are the order of the reaction under the following conditions?

The experimental rate of a reaction $$\ce{A + 2B -> C + D}$$ $$\frac{\mathrm dx}{\mathrm dt} = K[\ce{A}][\ce{B}]^2$$ Calculate the order of the reaction when (i) $[\ce{A}]\gg[\ce{B}]$ (ii) $[\ce{B}...
0
votes
1answer
542 views

Empirical formula, simplifying problems

Need some help with second part.....can't get it to be balanced and therefore can't find the formula and name! Thanks in advance! What is the empirical formula of each of the following compounds? a)...
0
votes
1answer
857 views

Finding the mole fraction

At $25\ \mathrm{^\circ C}$ the vapor in equilibrium with a solution containing carbon disulfide and acetonitrile has a total pressure of $263\ \mathrm{torr}$ and is $85.5\ \mathrm{mol}\text{-}\%$ ...
0
votes
1answer
814 views

Effect of an inert gas on steam vapor pressure at equilibrium

Suppose we have a closed container with mobile walls, so it will change its volume in order to equal the external pressure(constant) to the internal pressure. This container has inside it a liquid ...
0
votes
1answer
50 views

Why assume a neutral amino acid is given for acid-base reaction?

The questions is: $1.812\ \mathrm{g}$ of a crystallized α-amino acid ($\mathrm{p}K_\mathrm{a1} = 2.4, \mathrm{p}K_\mathrm{a2} = 9.7$) has a $\mathrm{pH}$ of $10.4$ when dissolved in $100\ \mathrm{...
0
votes
1answer
248 views

Explain why alumina-containing zeolites possess chemically active surfaces

I think zeolites possess acid sites that are catalytically active in many hydrocarbon reactions. The pore system only allows molecules that are small enough to enter, hence it affects the selectivity ...
0
votes
1answer
3k views

Solubility of silver acetate in the presence of nitric acid

What will be the effect on the solubility of $0.1\ \mathrm{mol}$ of $\ce{CH3COOAg}$ in presence of $1\ \mathrm{l}$ of $0.1~\mathrm{M}\ \ce{HNO3}$ solution? $$K_\mathrm{sp} (\ce{CH3COOAg}) = 10^{-...
0
votes
1answer
18k views

Calculate the pH of Na2CO3

Given information: $K_\mathrm{a}(\ce{H2CO3}) = 4.3 \times 10^{-7}$, $K_\mathrm{a}(\ce{HCO3-}) = 4.8 \times 10^{-11}$, ${{\ce{[Na2CO3]}=0.20\ \mathrm{M}}}$ This was a question in an exam and I'm ...
0
votes
1answer
2k views

How to determine the percentage of iron(II) and iron(III) in a solution?

Outline a plan of an experiment to determine the percentage of iron present as iron(III) in a solution containing $\ce{Fe^3+(aq)}$ and $\ce{Fe^2+(aq)}$ ions. You are provided with zinc, a standard ...
0
votes
1answer
2k views

Find molar concentration of sodium carbonate dissolved in water

The question is A solution of $\ce{Na2CO3}$ is made by dissolving $5.3~\mathrm{g}$ of the powder in enough water to make $250~\mathrm{mL}$ of solution. Find the molar concentration. I have done ...
0
votes
1answer
1k views

Hess's Law/Enthalpy of reaction

The problem: Chloroform, $\ce{CHCl3}$, is formed from methane and chlorine in the following reaction: $$\ce{CH4(g) + 3Cl2(g) ->3HCl(g) + CHCl3(g)}$$ Calculate $\Delta rH^{\circ}$, ...
0
votes
1answer
740 views

How does a lower pH change the alcohol concentration of wine?

I have been told it that when the pH of wine is lowered the alcohol concentration will decrease because of Le Chatelier's Principle. Which states; if a equilibrium is disturbed by changing the ...
0
votes
1answer
2k views

How to calculate the new concentration of a solution after adding more solute and convert it to ppm?

My question is the following: $2~\mathrm{g}$ table salt is added to $0.5~\mathrm{m^3}$ water whose salt concentration is $10~\mathrm{mg\,L^{-1}}$. Compute the salt concentration of the mixture in ...
0
votes
1answer
324 views

Interpretation of an H NMR

I am fairly new to NMR and require assistance to analyze and interpret the NMR I have provided (sorry for it being vertical). This is an unknown compound that I have derived during one of my lab ...
0
votes
1answer
569 views

How to calculate the amount of substance of nitrogen that dissolves in water?

The Henry's law constant for the solubility of $\ce{N2}$ gas in water at $298~\mathrm{K}$ is $10^5~\mathrm{atm}$. The mole fraction of $\ce{N2}$ in air is $0.8$. The amount of substance of $\ce{N2}$ ...
0
votes
1answer
204 views

Are there any strategies to determine bond order and hybridization rankings without drawing the Lewis Structure?

I'm not Chemist. I'm taking a chemistry class in college, and the test review contains many questions where I'm asked to rank from least to greatest based on bond order, polarity, and bond angles. I ...
2
votes
0answers
730 views

Precipitation of citric acid by CaCl2 and Ca(OH)2? [closed]

I need to precipitate citric acid from an aqueous solution in the form of calcium citrate. There are, to my knowledge, two different methods of doing this: using $\ce{CaCl2}$ and which will react ...