Questions tagged [homework]

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Why do the trends in reactivity not apply for francium?

Why is francium not included in the reactivity series? Why is potassium considered more reactive than francium? I know that reactivity increases down the group! But why does it not apply here?
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2answers
379 views

Development of retrosynthesis plan

I need to retro-synthetically design a valid synthesis plan (in 2 steps, from cheap starting materials available over at Sigma Aldrich) for a target compound, pictured below. How would I go about ...
5
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1answer
1k views

How to calculate the potential via Hess's law? Is my textbook wrong about this?

It is my understanding that to apply Hess' Law to this equation the top equation sign would be reversed and the outcome would be +0.65 V. Often the system produces incorrect answers. I was looking ...
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2answers
1k views

Titration of borax solution homework

Please check to see if there is anything that I should fix. Also, please check to make sure that my significant figures are correct. I am going to try to make it look like how I wrote it and how the ...
5
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1answer
88 views

Through bond interaction in biradical dioxo compound and its correlation diagram

I'd like to investigate into the ring opening, the migratory reverse reaction of the electrocyclic ring-closure of Dimethyldioxirane: As a first question I'd like to ask if I have drawn the through ...
4
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3answers
3k views

Identifying an unknown compound(w/ NMR/IR)?

I need some help identifying the following unknown compound. Any suggestions or hints regarding the possible compound would be highly appreciated. So far I am thinking the broad peak on the IR is an ...
4
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2answers
2k views

How do I find out what benzene containing compound this is with IR and NMR?

I have the following IR and NMR of an unknown substance. Can someone tell me what is a possible structure of the compound or point me in the correct direction. So far I am thinking of a benzene ring ...
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2answers
4k views

How to name this benzene alcohol?

The following is the molecule I am confused about. Earlier in my textbook it gives an example of how to name benzenes with 2 or more hydroxyl groups: My textbook (Nelson 12 Chemistry) is infamous ...
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3answers
9k views

How to derive the Gibbs free energy for an ideal gas?

Determine the Gibbs Free Energy for an ideal gas and show that, this energy, and its derivate can be related to the enthalpy of the system via Gibbs-Helmholtz equation $$H = -T^2 \left( \frac{\...
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1answer
531 views

Which hydrogen of 3-methylcyclohex-2-en-1-one is the least acidic?

According to me it should be 2, as on its removal there wont be any resonance stabilization as would happen in other cases. In addition to that a negative charge residing on a carbon attached to a ...
4
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1answer
795 views

What is the structure of this molecule?

I need to find the Lewis structure of the ion $\ce{SCH^-}$. I think the Lewis structure should be: $\ce{S=C-H}$ with one lone pair on the carbon and two lone pairs surrounding the sulfur. Is this ...
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2answers
3k views

Problems in the concept of ionic equilibrium

While trying to understand the solution of a problem given in my text book, I realized I'm having some difficulty with the solution. The problem is as folows: The ionization constant of HF is $3.2 \...
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1answer
2k views

Why is tetramethylammonium hydroxide a stronger base than tri- or dimethyl amine?

Of the following, which compound is the most basic?? $\ce{Me3N}$ $\ce{Me2NH}$ $\ce{Me4NOH}$ $\ce{NaOH}$ Between 1 and 2, 1 is more basic as the 3 methyl groups would produce a +I ...
4
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1answer
956 views

Rounding significant figures

Calculate how many grams of p-nitrophenol are required to prepare $250~\mathrm{mL}$ of a $11~\mathrm{mM}$ solution. (Answer to 3 significant figures.) I worked it out as $$\begin{align} \frac{250}{...
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1answer
2k views

What is the name of the compound Sc(HCO2)3?

I would like to know what the name of the compound $\ce{Sc(HCO2)3}$ is. I've been told that it is not scandium hydrogen carbonite and that it is not scandium formate. Any hints or suggestions about ...
4
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1answer
2k views

Is the largest number of molecules in 36 g of water or 54 g of dinitrogen pentaoxide?

So recently my teacher asked us which of the following has the largest number of molecules? He gave us two options: 36g of $\ce{H2O}$ 54g of $\ce{N2O5}$ I'm stuck, because both of them are having ...
4
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1answer
110 views

Identify this solution

The solution is emerald green in colour. When added with water, it gives a pale blue solution When reacted with $\ce{BaCl2}$, it gives a sky blue solution and a white precipitate. When reacted with $...
4
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2answers
12k views

Initial rate of reaction from the graph?

#13 , I tried finding the slope between two points but I keep getting wrong values, how do you find the initial rate? So I started by trying to find a slope of two points. (0,0.4) and (10,0.2) after ...
4
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1answer
205 views

Amide synthesis SM alkylchloride

Suggest a synthetic route to amide C from the alkyl chloride B (reaction mechanisms are not required). Standard reagents and solvents may also be used. In this question immediate reaction is to make ...
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1answer
86 views

Finding ppm getting too big of numbers

I have a question that is to find the concentration of magnesium ion in ppm for a $0.025\ \%$ solution of $\ce{MgCl2}$. I can use this formula: $$\text{concentration in ppm} = \frac{\text{mass solute}...
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3answers
44k views

Changes in which factors affect both the rate and the rate constant of a first order reaction?

Changes in which factors affect both the rate and the rate constant of a first order reaction? I. temperature II. concentration (A) I only (B) II only (C) Both I and II (D) ...
4
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1answer
494 views

how to distinguish between carbon-carbon double bond lengths

Which of the following should have the longest c=c? $$\begin{align} \text{a)}\ \ \ \ &\ce{CH2=C=CH2}\\ \\ \text{b)}\ \ \ \ &\ce{CH3 -CH=CH2}\\ \\ \text{c)} \ \ \ \ &\ \ \ \ \ \ \ \ \ \ \ ...
4
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1answer
219 views

Stereochemical outcome after elimination followed by addition

One of the following diastereomeric chlorides undergoes racemisation on heating whilst the other is returned unchanged. Explain. From the reaction conditions I can see that there must be an ...
4
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1answer
289 views

What is the mechanism for this nucleophilic conjugate addition?

My working so far: It seems theres not the extra C between S and carbonyl in this case...How do I carry on from here?
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1answer
2k views

Do ALL conversion factors have an infinite number of sigfigs?

Conversion factors have an infinite number of sigfigs, right? They should be exact values; but not all of them are, are they? I looked at http://www.webassign.net/question_assets/buelemphys1/...
4
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1answer
785 views

Finding average half life of radioactive nuclide which undergoes two different decays

Find the average life of a radio nuclide which decays by parallel paths $$A\rightarrow B$$ $$2A\rightarrow B$$ where the decay constants are $\lambda_1=0.018\ \mathrm{s}^{-1}$ and $\lambda_2=0.001\ \...
4
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1answer
174 views

How to determine the molecular formula based on molecular weight, amount of substance, and partial masses of some, but not all contained elements?

I am working on a chemistry assignment and can’t figure out part of the problem. $0.2\,\mathrm{mol}$ of a compound with a molecular weight of $82$ contain $9.6\,\mathrm{g}$ of carbon, $1.2\,\mathrm{g}...
4
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1answer
7k views

Solubility order for alcohols [closed]

Order for solubility of isomeric alcohols in a book was given as: Primary alcohol >Secondary alcohol >Tertiary alcohol After this I found a question as : 1) Which is more soluble in water? (a) 3-...
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1answer
2k views

Solid phase peptide synthesis (SPPS): why does capping after each coupling improve results?

The title more or less sums up my questions: why does capping after coupling improve results during solid phase peptide synthesis (SPPS)? The Case: I have conduced a lab experiment where we coupled ...
4
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1answer
883 views

Electronegativity and HCl and HF molecules

In a book I am reading, it is said In the $\ce{HCl}$ molecule, the shared pair of electrons spend more time nearer the chlorine atom. In the $\ce{HF}$ molecule, the shared electrons spend more time ...
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2answers
5k views

Finding rate constant at different temperature

For the reaction $$ \ce{2N2O5(g) -> 4NO2 + O2(g)} $$ the rate law is: $$ \frac{\mathrm{d}[\ce{O2}]}{\mathrm{d}t} = k[\ce{N2O5}] $$ At 300 K, the half-life is 2.50·104 seconds and the activation ...
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2answers
443 views

How does sugammadex (a modified cyclodextrin) draw rocuronium into its lipophilic cavity?

Sugammadex is a modified cyclodextrin: 8 member sugar ring with carboxyl thioether extensions. Rocuronium is an aminosteroid, 4 steroid rings and one protonated amine group. Sugammadex binds ...
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1answer
6k views

What are some good research topics for a high school student?

I absolutely love chemistry and I really want to take part in science fairs. I am also taking an AP chemistry class. Cleaner fuel and energy sources and air pollution (especially due to smog and ...
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2answers
2k views

For which pair of species is the difference in radii the greatest?

For which pair of species is the difference in radii the greatest? (A) $\ce{Li}$ and $\ce{F}$ (B) $\ce{Li+}$ and $\ce{F^-}$ (C) $\ce{Li+}$ and $\ce{O^2-}$ (D) $\ce{O^2-}$ and ...
4
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1answer
5k views

Constitutional isomers of cis-1,2-dibromocyclopentane

The following is a problem from Fundamentals of Organic Chemistry by McMurry. Draw two constitutional isomers of cis-1,2-dibromocyclopentane. I don't get how there can be constitutional isomers for ...
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1answer
2k views

How to calculate the mass of water to add to copper(II) sulfate to form a 4% solution?

How many grams of water are required to make a $4.00\%$ solution with $15.0~\mathrm{g}$ of copper(II) sulfate pentahydrate? I calculated the percent composition of water in a molecule of $\ce{CuSO4....
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2answers
512 views

Transition Metal Compounds

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
2k views

Organic conversion: benzene to 1-bromo-3-iodobenzene

Today, my chemistry teacher gave the organic conversion as homework. Benzene to 1-bromo-3-iodobenzene I tried something like: I am not sure about it, can someone review my conversion (as I have got ...
4
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1answer
98 views

Does esterification require reactants to be present in the same plane?

In the image that follows (7) I believe that the first step is the Cannizzaro reaction which will give (c) as a product. But since we are also adding $\ce{H+}$ in the second step, shouldn't an ...
4
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1answer
140 views

How to identify which of two given electrodes with corresponding solutions is reducing more?

For the sake of the question, let’s assume that you are provided with two labelled rods of the pure metals $\ce{A}$ and $\ce{B}$ and two unlabelled bottles containing $1.0\ \mathrm{mol\ dm^{-3}}$ ...
4
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1answer
10k views

Lewis structure of diazomethane

I tried to google and watch youtube videos on how to do lewis structures properly, but I cant seem to understand how to do this properly. My teacher, when class was in session, gave me a set of ...
4
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1answer
359 views

Converting organic carbonate to formate ester

I'm currently working on a chemistry project in which I need to convert the first organic compound to the second organic compound.(see image) I only have a simple background in organic chemistry (and ...
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1answer
2k views

Spectrophotometric assay by pNPP

Here is a series of related questions that I want to ask. If you think they ought to be different questions, please tell me so. Background The activity of acid phosphatase is measured by an ...
4
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1answer
940 views

How to find the units of the rate constant?

Consider the reaction $$\ce{2A + B -> Products}$$ When the concentration of $\ce{B}$ alone was doubled, the half-life did not change. When the concentration of $\ce{A}$ alone was doubled, the rate ...
4
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1answer
500 views

Are alkenes with bulky groups attached like the one shown in the picture chiral or achiral?

Is the compound in the picture chiral or achiral? I think it should be achiral for the following reasons: There is free rotation. I know, but for every configuration produced by free rotation ...
4
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1answer
426 views

Dissolving limestone in HCl and then neutralising the solution with NaOH

$15.0~\mathrm{mL}$ of $1.4~\mathrm{M}\ \ce{HCl}$ was mixed with $1.00~\mathrm{g}$ of limestone (impure $\ce{CaCO3}$) until all the solid had dissolved. The solution was then transferred to a conical ...
4
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3answers
18k views

How to determine the mole fraction of the liquid phase from a given mole fraction of the vapour phase for a benzene/toluene mixture?

A quantity of benzene, $\ce{C6H6}$, and toluene, $\ce{C6H5CH3}$, is placed in a $1~\mathrm{L}$ evacuated vessel at $25~\mathrm{^\circ C}$. At equilibrium, a small volume of liquid is visible at the ...
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1answer
90 views

Radiationless energy transfer: how to arrive at the equation that give R0 between two chromophores?

I have a homework question where I should calculate $R_0$ of an energy transfer between two chromophores. However, I don't understand how my professor arrived at the equation that we should apply (...
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2answers
200 views

How to determine the number of stereoisomers of a di-substituted allene, exhibiting both axial and central chirality?

What are the diastereomers and enantiomeric pairs of the compound below where A are chiral groups (central chirality)? There should be 3 diastereomers and 3 enantiomeric pairs (last page). I ...
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1answer
250 views

What is the reaction equation for a mixture of trichloroethanoic acid and dimethylpropanoic acid?

Write an equation for the reaction you might expect to take place if trichloroethanoic acid, $\ce{Cl3CCO2H}$, $\mathrm{p}K_a=0.65$, were added to dimethylpropanoic acid, $\ce{(CH3)3CCO2H}$, $\mathrm{p}...