Questions tagged [homework]

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313 views

How to estimate the concentration of OH that comes from just the autoprolysis of water in a basic solution?

In my analytical chemistry course, a question reads: What is the pH of a 0.10 M solution of THAM? Is it valid to neglect the autoprotolysis of water? Justify and explain your answer by estimating ...
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2answers
449 views

Reactions of ketones and aldehydes

Our topic was about ketones and aldehydes (carbonyl group) including hemiketals and hemiacetals and he asked us to do a homework. I cannot find an answer to this one.Please explain me the reaction and ...
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2answers
3k views

Volume change inside a balloon upon decreasing the the outer pressure

A balloon is filled with hydrogen at room temperature. It will burst if pressure exceeds 0.2 bar. If at 1 bar pressure the gas occupies 2.27 L volume, upto what volume can the balloon be expanded? ...
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1answer
234 views

What happens to the shielding of the proton when an alcohol is oxidized?

The full question: For H-NMR, the magnetic field experienced by a hydrogen atom can be externally applied or internally induced or some combination of the two. When the applied and induced ...
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1answer
536 views

Determine moles of limiting reagent

In the reaction involving 0.1 g of calcium nitrate and 1.5 g of sodium phosphate, what is the number of moles of the limiting reagent? Here is what I have so far: Balanced equation: $$\ce{3Ca(NO3)2 +...
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1answer
866 views

The temperature rise after neutralisation

The answer to this question is B, however, I don't quite understand. If considering Q= mc delta T, the heat released is to some extent being influenced by the no. of moles. If using that line of ...
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1answer
2k views

What is the correct order of chemical reactivity in terms of oxidising property for the following elements: F, Cl, O, and N

This is a textbook question. I am confused as to which factors i should consider while sorting out these elements. If I take electron gain enthalpy, then Cl should be greater than F, but if i consider ...
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1answer
107 views

Perovskite reaction equation (KMnF3)

For the synthesis of $\ce{KMnF3}$ I said the reaction equation was $\ce{3KF + MnCl2 -> KMnF3 + 2KCl}$ Is it this simple or are am I missing something with these particular types of reactions?
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893 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:}&...
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1answer
47 views

How do I figure out the amount of water (mL) and amount of Aluminum (g)?

We have a project where we have to extract copper from copper sulfate. But my group is given a powder version ($5~\mathrm{g}$), so we have to first dilute it with water and then combine it with ...
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1answer
118 views

How to convert an oxirane to an alkanol with one additional carbon atom?

This is a question given in our exam. In the reaction, Find the reagents X and Y required for steps(ii) and (iii) are _______ and ________ respectively. I have tried in this way but I have stuck in ...
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1answer
45k views

What is the effect of adding HCl on a certain solution at equilibrium?

If we have $$\ce{CH3COOH + H2O <=> CH3COO- + H+}$$ what is the effect on acetate ions when adding each HCl and NaOH to the solution? (State why according to Le Chatelier's principle) Le ...
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1answer
1k views

Understanding Standard Hydrogen Electrode

I came across a question today. A galvanic cell is composed of two hydrogen electrodes, one of which is a standard one. In which of the following solutions should the other electrode be immersed to ...
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1answer
105 views

Energy levels transitions of an electron?

I have an example that tells me that the energy transition between $n=1$ and $n=3$ is $12.1\ \mathrm{eV}$ using the following formula: $$E= -RH (\frac{1}{m^2} - \frac{1}{n^2})$$ and that the ...
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1answer
134 views

Calculate the heat of a reaction

Say I would like to calculate the heat produced by the following reaction: $$\ce{2SO2 + O2\longrightarrow2SO3}$$ I have calculated the moles of the reagents. I can't seem to figure out how to ...
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1answer
2k views

How to determine the products of a redox reaction

I'm doing a paper on water treatment methods, and in one section, I'm describing how a nearby water treatment plant is removing Trichloroethylene ($\ce{C2HCl3}$) from water by oxidizing it using Ozone ...
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1answer
2k views

Which statement is correct about electron orbitals and energy levels?

Which statement is correct about electron orbitals and energy levels? A. Yttrium, $\ce{Y}$ ($Z = 39$) is the first element in the periodic table with an electron in a f sub-level. B. The maximum ...
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1answer
2k views

What is the chemical redox equation between hydrogen peroxide and melanin?

I am investigating hair bleach, and want to figure out the redox reaction between $\ce{H2O2}$ (hydrogen peroxide) and $\ce{C18H10N2O4}$ (melanin). $\ce{H2O2}$ is a strong oxidizing agent in this redox ...
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1answer
195 views

What is the velocity of an ejected electron in lithium when subjected to UV radiation?

If UV radiation strikes an atom of lithium with one electron in its lowest allowed energy state with enough energy to eject the electron from orbit, what is the electron's velocity upon ejection? The ...
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1answer
84 views

Is this a feasible synthetic route for 1-(phenylethynyl)cyclopentan-1-ol?

From my notes $\ce{NaNH_2}$ is a good base for the deprotonation of alkynes. After the deprotonation I thought the alkyne would attack the carbon on the cyclopentanone because of the $\delta^+$ charge ...
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1answer
267 views

Precipitation with NaI

I dissolved $\ce{[Pt(NH3)4](NO3)2}$ in water then I added small amount of $\ce{NaI}$ ($1~\mathrm{M}$) to it. Precipitation occurred. I want to know what happened?
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1answer
151 views

How to calculate concentrations and what is the concept of 'mole'?

Say I have a $50~\mathrm{ml}$ solution of a liquid mixture which is $30~\%$ concentrated. Now if I take $20~\mathrm{ml}$ of that liquid out from that mix, what would be the resulting concentration of ...
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2answers
712 views

Transition Metal Compounds [closed]

So I have a few dumb questions. I'm still in high school and am doing something on magnetic properties of transition metals. I'm facing a few roadblocks. 1) What're compounds like $\ce{CoBr2, CoCl2, ...
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1answer
106 views

Dilution with 3 Different Percentages

I'm trying to solve this problem. How many grams of a solution at $25\%$ do you have to add to $100\ \mathrm{g}$ of a solution at $40\%$ to obtain a solution at $30\%$. My Attempt It's a bit ...
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1answer
56 views

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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1answer
2k views

What is the mass fraction of C2HCl3 in the liquid phase?

Vapour-liquid equilibrium of a two-component ideal solution of trichloroethene (C2HCl3) and trichloromethane (CHCl3) is established at 25 °C. The mole fraction of CHCl3 in the vapour phase is 1. What ...
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2answers
708 views

TLC plate and Rf values

I have calculated the Rf values for 6 samples. How do I determine which is really Sriracha ?
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1answer
1k views

How to calculate the volume of a 0.1 M NaOH(aq) solution necessary to make a 0.5 M EDTA solution with pH = 8?

I was told that EDTA dissolves at a pH of $8$. Therefore I need to use a base to increase the pH to $8$ is what I understand. How exactly would I go about this? In my head I if I wanted $1~\mathrm{L}...
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0answers
317 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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1answer
1k views

Thermochemistry Problem - How did they get that volume?

The chemistry problem in my textbook is : Calculate the work one when 2.0 L of methane gas, $\ce{CH4}$ (g) undergoes combustion in excess oxygen at 0ºC and 1.00 bar. Assume the volume of water formed ...
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1answer
961 views

Finding the mass of NaNO3 in original mixture from preciptate

A 1.61-g sample of a mixture of $\ce{AgNO3}$ and $\ce{NaNO3}$ is treated with excess $\ce{Na2S}\:(\mathrm{aq})$. The precipitate is filtered off, dried and weighed. The dried precipitate weighs 0.44 g....
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1answer
1k views

Determine the mole fraction

Under certain conditions, the well-known fertilizer $\ce{NH4NO3 (s)}$ explodes according to the following balanced reaction: $\ce{2NH4NO3 (s) -> 2N2 (g) + 4H2O (g) + O2 (g)}$ Exactly 8 g of $\ce{...
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1answer
1k views

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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2answers
3k views

Getting the molality of a solution given molarity and density

If a solution of $\ce{HNO3}$ has a molarity of 16 and a density of $1.42\ \rm{g/mL}$, what is the molality of the solution? Well, a molarity of 16 means that there are 16 moles of solute for every ...
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1answer
301 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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1answer
115 views

Original concentration calculation homework

A student performs the following gravimetric analysis of iron ions in a water system $$\ce{Fe^2+ (aq) + CO3^2- (aq) <=> FeCO3 (s)}$$ If this student used excess carbonate and obtained the ...
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2answers
4k views

How does valency change in a reaction?

There is a reaction given in my book: $\ce{2FeSO_4 +Heat -> Fe_2O_3 + SO_2 + SO_3}$ I just noticed that on the left $\ce{Fe}$ has valency $2$, while it has $3$ on the right. How can it change ...
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1answer
435 views

Which of the following have the same molecular formula as the molecule shown in the model?

This model has 3 hydrogens connected the the first and last carbon and 2 hydrogens connected to the other carbons Finding the same molecular formula as the alkane model I have to check all that apply ...
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2answers
117 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 ...
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1answer
4k views

How to calculate concentrations in a diluted mixture of multiple solutions?

I have a homework problem as follows: A solution was prepared by mixing $25.0\ \mathrm{mL}$ of $0.208\ \mathrm{M}$ $\ce{Fe(NO3)3}$ and $4.50\ \mathrm{mL}$ of $0.00190\ \mathrm{M}$ $\ce{KSCN}$ and ...
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1answer
7k views

Convert grams of water to steam

I'm working through problems in my textbook. How much heat is required to convert 2.55 g of $\ce{H2O}$ at 28 °C to steam at 100 °C? In simpler problems I've used the fact that $\Delta H_\text{fus} = ...
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1answer
2k views

What are all the stereoisomers of 1-ethyl-3-methylcyclohexane?

What are all the stereoisomers of 1-ethyl-3-methylcyclohexane? The following image shows my attempt to answer the question. But I am not sure if I am correct. Note: I am treating this cyclohexane as ...
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1answer
3k views

How to convert ethanal to 2-hydroxy-3 butenoic acid?

How to convert ethanal to 2-hydroxy-3 butenoic acid? I tried crossed aldol condensation with formaldehyde followed by acid addition.After that how should I proceed ?
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1answer
89 views

Identification of solutions by solubility when mixed with each other

$\ce{Pb^{2+} (aq), Cl- (aq), Ag+ (aq), (SO4)^{2-} (aq)}$. You number the four bottles, 1,2,3,4and while numbering them, you notice that bottles 1 and 3 have the word "cation" on their lids while ...
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1answer
2k views

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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2answers
2k 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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1answer
147 views

The difference between the different types of rhodamine

What is the difference between different type of rhodamine, for example rhodamine red and rhodamine green? are these two type of rhodamine (red & green) have a good Raman signal? We would like ...
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1answer
589 views

For the half reaction HSO3- -> S2O6^2- why is it that 2e- are on the right hand side when balancing and not one electron?

$$\ce{HSO3- -> S2O6^2-}$$ The oxidation number of $\ce{S}$ on the left is +4 and +5 so when adding electrons to balance the oxidation number why is $\ce{2e-}$ added to the right instead of one? ...
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1answer
322 views

Why/How am I calculating freezing point depression wrong?

What is the freezing point of water made by dissolving $\mathrm{10.11~g}$ of magnesium chloride in $\mathrm{86.03~g}$ of water? The freezing-point depression constant of water is $\mathrm{1.86~^\...
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2answers
111 views

Titration of C₄H₆O₂

$\ce{C4H6O2}$ (10.75 g) was dissolved in water (250 cm3) and then a 20 cm3 sample was titrated against an alkali metal hydroxide solution. This required 17.35 cm3 of the alkali. What was the ...