Questions tagged [homework]

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1answer
9k 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-...
4
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2answers
591 views

How to properly rearrange the first law of thermodynamics?

For class we have been asked to show how the First Law of thermodynamics. $$\mathrm dU = \mathrm dQ + \mathrm dW$$ can be shown to be $$\mathrm dQ = \frac{C_V}{R}V\,\mathrm dP + \frac{C_p}{R}P\,\...
4
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2answers
628 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, ...
3
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1answer
6k views

Why does Phosphorus trifluoride molecule have dipole moment?

My book says that from drawing the Lewis structure for the molecule below, you can conclude that it has dipole moment. Can someone please explain why? I understand that the dipole moment expresses ...
3
votes
1answer
201 views

pH of a redox reaction between nickel(IV) oxide and silver

For the following reaction: $$\ce{NiO2(s) + 4 H+(aq) + 2 Ag(s) -> Ni^2+(aq) + 2H2O(l) + 2Ag+(aq)}$$ $$ E^\circ = 2.48\ \mathrm V$$ Calculate the $\mathrm{pH}$ of the solution if $E = 2.23\ \...
3
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2answers
18k views

How to calculate the percentage of calcium carbonate in sea shells in an experiment [closed]

We have a investigation in my chemistry class in which we must calculate the amount of calcium carbonate in sea shells. We can have as many sea shells as we wish, lab equipment, and hydrochloric acid ...
3
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1answer
6k views

How to calculate the van der Waals radius of ethane?

Calculate the van der Waals radius for ethane if $b = 0.0493\ \mathrm{dm^3\ mol^{-1}}$. $$b = 4 \times {4 \over 3}\pi \times r^3 \times N_\mathrm A$$ $$\implies r = \sqrt[3]{3b\over 16\pi N_\mathrm A}...
2
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2answers
904 views

Synthesis of 2-benzylcyclohexan-1-ol from cyclohexanone

There are no conditions given and a mechanism is required. I first thought it could be along the lines of Claisen rearrangement but that needs an aromatic ring. Since the Claisen rearrangement can't ...
2
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3answers
292 views

Is the amount of cubic inches in a cubic foot exact?

I know we are supposed to use SI units and I know they are defined very well. But does that mean that Imperial units of length/volume aren't exact? Don't they have infinite significant figures in ...
2
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3answers
1k views

What are the most important resonance structures of 5-aminocycloheaxa-2,4-dienone?

Here attached is a question from my exam. My TA removed 1 point out of 7 for a reason. Can anyone decipher for what? There's the writing in red but it is illegible to me. I don't understand to what he ...
2
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2answers
2k views

How do i convert benzoic acid to meta-fluorobenzoic acid?

in not more than 3 steps. i did it but the process was a little long. here is my attempt
2
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2answers
4k views

Most acidic compound amongs the following unsaturated ketones?

In the given picture, I know that the most acidic will be (a), because of potential of ring expansion. I tried a few times but wasn't able to get a satisfactory six membered ring. I think (a) is the ...
2
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2answers
3k views

Kinetic isotope effect in nitration of benzene

What is the effect of changing all the hydrogen atoms in benzene to deuterium? For example, which of the following reactions occurs at a faster rate?
2
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2answers
312 views

Why is the second reaction being neglected?

If we want to find the concentration of $\ce{H+}$ ions at equilibrium when a weak conjugate base such as $\ce{C2H3O2-}$ added to water, why do we take the conjugate base reaction for calculation i.e $$...
2
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2answers
61k views

Calculate the pH of acetic acid for a 0.02 M solution

We have a solution $\ce{CH3COOH}$ (acetic acid) with $c=0.02~\mathrm{mol/L}$ and the of acetic acid, $K_A = 1.8\cdot10^{-5}$. Calculate the $\mathrm{pH}$ of this solution. I tried everything but I ...
2
votes
1answer
21k views

What total energy (in kJ) is contained in 1.0 mol of photons, all with a frequency of 2.75 • 10¹⁴ Hz?

There is a question, that says: What total energy (in $\mathrm{kJ}$) is contained in $1.0~\mathrm{mol}$ of photons, all with a frequency of $2.75 \cdot 10^{14}~\mathrm{Hz}$? My answer was: The ...
2
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2answers
799 views

Concentration, how to determine grams of NaCl needed

Disclaimer: It has been a very long time since I have done any chemistry. My friend posted this question on social media, I've copy+pasted it here: Exactly $16.0~\mathrm{ml}$ of a solution A is ...
2
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1answer
2k views

Ring expansion and carbocation formation

If in a reaction the carbocation is formed outside the ring then why does the ring expansion does not happen as follows:
2
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1answer
2k views

What is the mechanism for the double bond migration in 4-methylcyclopent-2-en-1-one?

Please explain using only enolisation and protonation steps: My workings so far: Seems completely wrong... Can someone please correct me? *i just proposed a new mechanism:
2
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2answers
3k views

What does all chromatography have in common?

We're learning about chromatography in class, and I'm confused about all the different types (e.g. those that separate liquid-liquid solutions vs. those that separate liquid-solid solutions vs. those ...
2
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2answers
398 views

Why isn't helium always He 1s?

Part 1: According to what I've learned so far, helium is in the first row of the periodic table, so its $n$ should always equal $1$. However, a question in my text asks about helium 2s. What is helium ...
2
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4answers
513 views

Could I get a hint on the structure of this molecule based on HNMR spectra?

Chemical formula is $\ce{C7H6O3}$. IR spectra has a peak at 3238, which I believe could be an alcohol, phenol, or carboxylic acid. There's an additional peak at 3015, which I believe is either an ...
2
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2answers
2k views

When is rotation around double bonds to form cis-trans isomers allowed?

The Rhodopsin molecules in the retain contain a derivative of vitamin A called cis-retinal (Figure 6). On exposure to light, cis-retinal becomes an isomer called trans-retinal (Textbook Question). ...
2
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3answers
3k views

Fischer to Haworth projection: which carbon connects to the oxygen?

For D-erythose, carbon 4, (the last carbon), connects to the O which connects to Carbon 1. However, for D-glucose, carbon 5 (the 2nd last carbon) attaches to the O which attaches to carbon 1. Why ...
2
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1answer
8k views

Hybridization of tetraamminecopper(II) sulfate

$\ce{Cu^2+} $ has 9 electrons and a d-orbital and is almost completely filled (except 1 electron vacant) and $\ce{NH3}$ donates an electron eventually forming $\mathrm{sp^3}$ hybrid orbitals. But it ...
2
votes
2answers
1k views

Using sigfigs when measuring with an instrument with marks other than powers of ten?

If an instrument does have markings that are powers of ten, then finding the precision of the instrument is easy. For example, if a graduated cylinder had markings for every 0.1mL, or every mL, or ...
2
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2answers
3k views

Symmetry representations for CH3CN

Can anybody share the symmetry labels for acetonitrile ($\ce{CH3CN}$), please? I mean I to assign the symmetry labels to orbitals of acetonitrile
2
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1answer
6k views

Calculating the concentration of salt water

$23.4\text{ g}$ of $\ce{NaCl}$ are dissolved in $100\text{ g}$ of water. Calculate concentration of salt in the solution. Here's my work: Number of moles of salt is $0.4\text{ mol}$ Volume of ...
2
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2answers
22k views

How do I figure out the relative polarity of organic compounds?

It's a question on my quiz which I guessed right and couldn't do the reasoning: Based on the intermolecular forces, predict the boiling points of the following substances and list them in the order ...
2
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1answer
276 views

Kinetics of an irreversible bimolecular reaction

Assume the reaction $$\ce{A + B ->} \text{Products}$$ is of second order kinetics and that the rate constant is $k$. The differential equation is given by $$\frac{\mathrm d}{\mathrm dt} [\ce{A}] = -...
2
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3answers
641 views

When should we not draw a Lewis dot structure?

My friend once told me that technically , we should not draw Lewis dot structure of molecules containing no central atom.(eg.benzene,acetic acid) Is he right ? If yes, then what is the reason behind ...
2
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2answers
1k views

Why is lead sulfide found in nature, whereas lead oxide is less common?

This question probably applies to other heavier metals as well. The only rationalization I can figure is that lead in the +2 oxidation state (which is most common) is a borderline soft acid and ...
2
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2answers
3k views

How do I write the net ionic equation for a reaction I observed

I am currently taking a general chemistry course and during a lab they had us do the following procedure: Place 2mL of 5% $ \ce{NaClO} $ solution in a test tube. Add 10 drops of cyclohexane. Add ~10 ...
2
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1answer
690 views

Bond length comparison between sulfur tetrafluoride and thionyl tetrafluoride

I'm comparing sulfur tetrafluoride and thionyl tetrafluoride. The lone pair has more s character compared to a double bond. Therefore, sulfur in $\ce{SF4}$ should have a greater s character compared ...
2
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1answer
159 views

How many alkane of molecular weight hundred are chiral

I successfully made 2, but answer key says that there are 4 such compounds possible. I made: 3-methyl hexane 2,3-dimethyl pentane What else could be made folks?
2
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2answers
717 views

Geometry of buta-1,3-dien-1-ol

Consider the molecular formula $\ce{CH2=CH-CH=CH-OH}$ $(\ce{C4H5OH})$. Tell the types of bond, hybridizations, bond angles and geometry of this compound. So I didn't have any trouble with the first ...
2
votes
1answer
570 views

What would the phosphorus-NMR of trifluorodiphenylphosphorane look like?

I'm fairly new to NMR especially $\ce{^{19}F}$ and $\ce{^{31}P}$ NMR, we've not been formally taught NMR yet but we're expected to know $\ce{^{19}F}/\ce{^{31}P}$ NMR for our exam for basic molecules. ...
2
votes
1answer
805 views

Sulfurous acid tautomerisation

In the structure of $\ce{H2SO3}$ there is a lone pair on sulfur. Why can't sulfur make a bond with one of the hydrogen atoms and a double bond with oxygen to avoid lone pair?like given below because ...
2
votes
1answer
813 views

Why can't electrons be transferred using hydrogen ions?

I have a homework question that asks: Recognizing how oxidation and reduction occurs is essential for analyzing and understanding biochemical reactions. Which of the following methods would NOT be ...
2
votes
1answer
16k views

What is the IUPAC name of [Co(NH3)5H2O]Cl3?

I am not getting if it is Pentaammineaquo cobalt(III) chloride or Aquopentaammine cobalt (III) chloride-should the prefix be ignored while naming the ligands in alphabetical order? Besides how should ...
2
votes
3answers
820 views

What is the enol form of 4-methylcyclohex-2-en-1-one?

What is the enol form of this compound? I have made an attempt, but it doesn't look quite right. Also which hydrogen should be taken off (left or right hand side of the carbonyl)? And I dont think ...
2
votes
1answer
1k views

Determine the isotope half-life?

A sample of $\ce{^{41}Ar}$, a radioisotope used to measure the flow of gases from smokestacks, decays initially at a rate of 34,500 disintegrations/min, but the decay rate falls to 21,500 ...
2
votes
1answer
655 views

Can a Cl atom bond with a non-carbon atom?

I am currently doing the questions: Write equations for the reaction of Chlorine with Propene and 2-butene using structural So I know that Propene is $\ce{H3C-CH=CH2}$ and $\ce{Cl}$ is $\ce{...
2
votes
2answers
183 views

the oxidation number of N in this equation?

the equation : $\ce{NH4Cl + AgNO3 -> NH4NO3 + AgCl}$ I know that oxidation number of $\ce{N}$ in $\ce{NH4Cl}$ is -3 and in $\ce{AgNO3}$ is +5 but what I am confused about is the oxidation ...
2
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3answers
7k views

Use of osmosis to measure molecular weight of macromolecules

How can osmosis be used to measure molecular weight of macromolecules ? Is it applied practically ?
2
votes
1answer
355 views

Naming alkyl groups of an ester

$\hspace{6.4cm}$ I would like to know how to name the alkyl groups connected to the above molecule. For example, would the far left alkyl group be considered a methyl ester group? Would the alkyl ...
2
votes
1answer
286 views

Calculating Ratio of Stability Constants

Solution I contains a mixture of $\ce{FeCl2}$ and $\ce{FeCl3}$, and solution II contains a mixture of $\ce{K4Fe(CN)6}$ and $\ce{K3Fe(CN)6}$. The concentrations of iron-containing species satisfy the ...
2
votes
1answer
2k views

How to derive Van't Hoff equation for Henry's constant

While studying about Henry's Law, I encountered this equation,I didn't know how to derive it so I searched about it and got nothing, I tried to substitute $H$ (Henry's const.) by $\gamma\cdot f_i$ ...
2
votes
1answer
925 views

Find the number of water molecules “embedded” in sucrose

Recently I got a question as follows: How many molecules of water are joined with 12 atoms of carbon in a molecule of sucrose ? (A) 12 (B) 11 (C) 6 (D) 10 I am unable to ...
2
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1answer
59 views

Ratio of Tb ions?

Estimate the ratio of $\ce{Tb^3+}$ to $\ce{Tb^4+}$ in $\ce{Tb_6O_11}$ ? For my solution I knew that I had to get a sum of 22 from 6 $\ce{Tb^3+}$ and $\ce{Tb^4+}$ ions so I just added different ...

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