Questions tagged [homework]

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What is the specific heat of copper through its phases?

Specific heat is the amount of heat required to change the temperature of 1 gram of a substance by 1 Celsius. For instance, the specific heat of water in the solid phase is 2.059 J/gC and 4.184 J/gC ...
1 vote
3 answers
6k 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. ...
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2 answers
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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 ...
1 vote
2 answers
288 views

Predict the standard potential at 310 K for the cell constructed from the hydrogen electrode and metal-insoluble salt electrode

I've run into trouble on this question Predict the standard potential at 310 K for the cell constructed from the hydrogen electrode and metal-insoluble salt electrode $\ce{Ag(s)|AgCl(s)|Cl-}$. ...
-1 votes
1 answer
284 views

Does no optical rotation always implies optical inactivity? [duplicate]

This question popped up in my mind in reference to this question, Is a compound optically active if plane polarised light is deflected by an angle of n*(2π) angles? Suppose that I give a chemistry ...
-1 votes
1 answer
872 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 ...
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2 answers
85 views

Inhibitors reaction at home

For a school science project, my teacher asked me to find a reaction that can be slowed down with an inhibitor and film it at home/lab at school. He told not to use lemon on an apple or anything ...
-2 votes
2 answers
75 views

Intesive Properties - Temperature [closed]

Why is the temperature of a sample of matter intensive? I don't think it would be extensive, but I also don't see why it would be intensive, either. It's a very basic and easy question, but I can't ...
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1 answer
6k 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 : $...
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2 answers
4k views

Temperature Dependent Specific Heat of Nitrogen

Calculate the change in enthalpy as 1kg of nitrogen is heated from 1000K to 1500K, assuming the nitrogen is an ideal gas at a constant pressure. The tempreature dependent specific heat of nitrogen is ...
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1 answer
1k 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 ...
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1 answer
2k views

How do I calculate the enthalpy change when a gas is being used to heat water?

The question I'm trying to answer is: Calculate the mass of butane gas that would be needed to heat $724\ \mathrm{cm^3}$ of water from an initial temperature of $7.44\ \mathrm{^\circ C}$ to $50.7\ \...
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2 answers
140 views

Hydrolysis of Radiolabeled Esters

Hydrolysis of C$_6$H$_5$COO$^{18}$CH$_3$ with aqueous NaOH produces what final product. (a) CH$_3$$^{18}$OH (b) CH$_3$CO$^{18}$ONa (c) CH$_3$C$^{18}$OONa (d) CH$_3$$^{18}$ONa (e) CH$_3$OH The ...
-2 votes
2 answers
5k views

How to calculate the molar mass of a protein from its osmotic pressure?

I am unsure how to go about solving this question. I know how to get the osmotic pressure, but where do I go from there? I can't use the gas law since the protein is not a gas. $\pu{2.38 g}$ of a ...
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1 answer
45k views

Metal vs. Styrofoam cup calorimeter?

For a metal cup as opposed to a styrofoam cup calorimeter, do you expect the enthalpy of the reaction to be higher, lower, or the same? I think the enthalpy of the reaction would be the same in the ...
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1 answer
6k views

Galvanic cell using NaCl, Cu and Zn, why does it work?

Got a paper due tomorrow in chemistry, and my friends and I are totally stuck on this: Basically we mixed some regular salt (NaCl) into a glass of water and stuck a zinc nail and a copper nail into ...
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1 answer
2k views

Relation between number of equivalents of reactants

Consider the reaction $\ce{Sb2S3 + F2 -> SbF5 + SF6}$. If the milliequivalents of antimony, sulfur and fluorine are x, y and z respectively, then prove that $x+y=z$. This is what I know: Number of ...
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2 answers
552 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 ...
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2 answers
7k views

How does this method of calculating the water equivalent of a calorimeter work?

I am doing a AP Chemistry lab in which we determine the heat capacity of a calorimeter (a concept that seems like it should depend on a lot more than just the calorimeter.) We have to calorimeters ...
1 vote
1 answer
5k 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 ...
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2 answers
26k 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 ...
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1 answer
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 $\...
1 vote
0 answers
411 views

Does PO3- exist as a free ion or in a cyclic/linear polymeric form? [closed]

My book says that $\ce{PO3-}$ exists as cyclic or linear polymeric structure but doesn't elaborate on this. I Googled this and found no result either. Also, what would be the structure of $\ce{PO3-}$...
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1 answer
868 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 ...
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2 answers
429 views

What is the wavelength of an electron?

The kinetic energy of an electron is $1.67 \times 10^{-17}\mathrm{J}$. Calculate the wavelength ($\lambda$) of the electron. I know the formula $\lambda= \frac{h}{mv}$; where h is Planck's constant. ...
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1 answer
1k views

Explain the difference in stability of permanganate ions in acidic/ alkaline solutions?

The question is such: Use the data to comment on the stability of $\ce{MnO4-}$ in acidic and basic solution. Suggest a reason for this difference. $$\begin{align} &\text{acidic solution:}&...
-1 votes
1 answer
2k 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 ...
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1 answer
9k 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?
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2 answers
26k views

How to write equations for dissociation of ionic compounds in water?

Please write a dissociation-in-water equation for the compounds $\ce{BeI2}$ and $\ce{LiI}$. Make sure to add the states of matter after each compound. Currently, for $\ce{BeI2}$ I have the equation $$...
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1 answer
3k 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 ...
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2 answers
47k 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 ...
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1 answer
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How high in (mmH2O) is the column of water in the tube?

A long glass tube, sealed at one end, has an inner diameter of 23.4 mm. The tube is filled with water and inverted into a pail of water. If the atmospheric pressure is 735 mmHg, how high (in mmH2O) is ...
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2 answers
4k views

Calculating molar conductance of CaCl2

Ok, so the following question is given in my text book. Of the molar conductance value of $\ce{Ca^2+}$ and $\ce{Cl^-}$ at infinite dilution are respectively $118.88\times10^{-4}$ and $77.33\...
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1 answer
143 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) ...
1 vote
2 answers
2k 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. (...
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1 answer
385 views

Equivalent Line Angle Structures?

Are the following equivalent structures for 2,2-dimethylpropane? I think so, because my rendering simply rotates the cross 45 degrees! Also, regarding 3,3-diethylpentane, are these both equally ...
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1 answer
660 views

Using gas laws to find density

An unknown gas at $\mathrm{63.1\ ^\circ C}$ and $\mathrm{1.05\ atm}$ has a molar mass of $\mathrm{16.04\ g/mol}$. What is the density of the gas? I know I need to use the $pV=nRT$ equation but it ...
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2 answers
2k 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: ...
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1 answer
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Reaction of 1,1-diphenylethanol on Montmorillonite K10 under microwave radiation

What is the product of 1,1-diphenylethanol + Montmorillonite K10 Clay undergoing microwave radiation? What is the mechanism for it? My effort: 1,1-diphenylethanol + Montmorillonite K10 Clay catalyst ...
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1 answer
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Mr of Acid getting wrong answer

I am preparing for A level chemistry exams. One of the questions I came across is Calculate the $M_\mathrm r$ of unknown monoprotic acid. The volume is $15\,\rm cm^3$ and concentration $10.95\,\rm ...
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1 answer
251 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 ...
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1 answer
430 views

Is 2,3-dimethylprop-1-ene a possible organic structure?

Is 2,3-dimethylprop-1-ene a possible organic structure? I am not sure how to approach this, what would the correct name of this molecule be?
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1 answer
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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 ...
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3 answers
8k 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 ...
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2 answers
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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 ...
1 vote
1 answer
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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{...
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1 answer
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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 $\Delta rH^{\circ}$, ...
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1 answer
688 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 ...
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1 answer
9k views

Calculating collision diameter with viscosity, but not having the mass given

I've got a homework question i'm stumped on. The viscosity of the ethylene gas was measured at $99.8\times10^{-7}\ \mathrm{N\ s\ m^{-2}}$ at $288\ \mathrm K$. Calculate the collision diameter in $\...
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1 answer
6k 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 ...