All Questions

1
vote
2answers
145 views

How does Le Chatelier's principle apply to a gas phase reaction at constant volume?

This reaction is given in my book and the direction of shift of reaction on addition of $\ce{CO}$ and removal of $\ce{CO2}$ at constant volume is asked. $$\ce{2CO(g) + O2(g) ⇌ 2CO2(g) + \Delta H}$$ If ...
1
vote
1answer
29 views

Is it more precise to measure a substance as a solid or as a liquid?

If I have a substance and want to obtain an exact quantity of it, is it better to measure it as a solid or as a liquid? In other words, if I have, for example, NaCl crystals I can weigh the crystals ...
1
vote
2answers
44 views

Calculate Gibbs energy of dinitrogen pentoxide using its vapor pressure and sublimation

I am having trouble with the following problem: Dinitrogen pentoxide, $\ce{N2O5}$, is a solid with a high vapor pressure. Its vapor pressure at $\pu{7.5 °C}$ is $\pu{100 mmHg}$, and the solid ...
0
votes
0answers
3 views

Why does monoammonium phosphate (MAP) have 52% of phosphorus (P2O5)?

The formula of monoammonium phosphate (MAP) is $NH_4H_2PO_4$. Manufacturers say that MAP has 10% of nitrogen (N) and 52% of phosphorus (P). However, its molecular mass is 115 u and the atomic mass of ...
2
votes
1answer
64 views

Possible erratum in solutions to Orbital Interactions in Chemistry 2ed [on hold]

I was attempting the problems in Chapter 1 of Orbital Interactions in Chemistry, and found a slight problem. ftp://ftp.wiley.com/public/sci_tech_med/orbital_interactions_2e/Chapter%201%20-%20Answers....
9
votes
2answers
512 views

Inorganic chemistry handbook with reaction lists

There is a handy handbook on common inorganic substances' properties called "Reactivity of Inorganic Substances" (eds. R. A. Lidin, V. A. Molochko, and L. L. Andreeva). It was originally written in ...
-2
votes
0answers
35 views

Mass-Charge balance equations

How to write mass balance equations and charge balance equations of the solution composed of $\pu{0.1M}\text{ }\ce{ NaH2PO4}~ \text{and}~\pu{0.05M}\text{ }\ce{ Na2HPO4}$? After writing the equilibria ...
0
votes
0answers
4 views

Where can I look for a short chain photopolymer?

I am by no means an expert in this field, so please be patient with my explanation. I am looking for a photopolymer with very specific properties. I am not sure how realistic it is to find such a ...
-1
votes
0answers
34 views

Definition of conjugation and Dewar resonance energy [on hold]

What is a precise definition of conjugation in organic molecules? Why, for instance, do we say a molecule like 1,3-butadiene is conjugated? A valence bond picture might argue the opposite, since ...
1
vote
0answers
27 views

MacGyvering medieval poison

Anyone know of any compound/substance one could have access to in a stone prison cell (From food? The rocks? The metal bars?) that could be processed through rudimentary means into a quick acting ...
0
votes
1answer
17 views

Buffer Systems, K(NH2)2 and HCL [on hold]

25 .00ml of 0.100M R(NH2)2 with $Kb1=1*10^{-4}; Kb2 = 1*10^{-7}$ is mixed with amounts of .100M HCL a.) 0 ml b.) 5ml c.)10ml d.)12.5ml e.)25.00ml f.)37.50ml g.)50.00ml h.)60.00ml What is ...
0
votes
1answer
19 views

What is the platinum doing in a Zippo hand warmer?

My Zippo hand warmer requires lighter fluid, platinum catalytic burner, and a heat source to start the flameless catalytic process. What is the platinum doing in this reaction?
0
votes
0answers
21 views

Confusion with molarity calculations

I am asked to calculate the molarity of TNB and BSA in assay and got a bit confused with the numbers. I know that the assay volume is 3ml and concentration of DTNB is 5ooµM, concentration of BSA is ...
1
vote
1answer
20 views

What is the reason for more stable keto form to tautomerise to a less stable enol form?

In the mechanism of SeO2 I have seen that a more stable keto form first converts to a less stable enol form and then yields a diketone. I have seen many other reaction where the reactant converts to ...
-1
votes
0answers
22 views

Thermal Decomposition of nitrates [on hold]

I would like to see a visualisation of the thermal decomposition of nitrates. Something similar to this, from that I can understand a metal oxide and carbon dioxide would be formed, but for nitrates: ...
0
votes
1answer
26 views

Why aren't all double bond lengths equal in cyclobutadiene? [on hold]

even when there is a possibility of conjugation why aren't bond lengths equal?
0
votes
0answers
13 views

How does chelation control result in rate acceleration?

In the chapter on diastereoselectivity in Clayden, Warren & Greeves (2012), the Cram-Chelate model is discussed. Most significantly, under chelation control, the diastereoselectivity of the ...
0
votes
0answers
15 views

Conflicting info on TRIS buffer - pH6.8

I was about to prepare buffer for milk enzyme and to follow prep method described on bio-rad. But then I became suspicious and came across tons of information that pH6.8 is not in effective pH range ...
2
votes
0answers
22 views

How to take a sample of a hot salt solution without it precipitating in the cooler glassware due to the difference in solubilities at different temps?

I'm doing an investigation to see the effect of temperature on the solubility product of strontium hydroxide. I made a supersaturated solution left in the oven overnight at 85°C for equilibrium to be ...
0
votes
0answers
19 views

Parent and molecular geometry [on hold]

is the molecular geometry for carbon in formic acid trigonal planar. Also is the parent geometry for carbon in formic acid trigonal planar as well. Whilst the molecular geometry for hydroxyl oxygen in ...
8
votes
3answers
707 views

Identify KNO3 and KH2PO4 at home

I am not expert in chemistry. I need to find a way to identify a $\ce{KNO3}$ and $\ce{KH2PO4}$ powder at home. I suspect the seller gave me the wrong powder. What is a simple way to test between these ...
17
votes
2answers
908 views

Is it possible to speed up radioactive decay?

I’m aware that elements like $\ce{^14C}$ have a known half-life, which means that over a span of roughly $5730$ years, half of the $\ce{^14C}$ atoms decay into $\ce{^14N}$. Are there any substances ...
3
votes
0answers
32 views

Oxidation of diols using periodic acid

What are the orders of rates of oxidation with $\ce{HIO4}$ of the following diols? Explain with reasons. (a) $\ce{Me2C(OH)C(OH)Me2}$ (b) $\ce{Me2C(OH)CH(OH)Me}$ (c) $\ce{CH2(OH)CH2(OH)}$ (d)...
3
votes
1answer
36 views

HCl rota-vibrational lab: ab initio simulation of rotation constants

I'm trying to set up the simulation portion of the classic undergraduate lab studying the rotavibrational spectrum of HCl and DCl. In terms of simulation (using Gaussian 16), the equilibrium ...
-1
votes
1answer
19 views

How do amphoteric compounds act as acids?

According to my chemistry textbook, an acid is a compound that gives hydronium ion on dissolving in water but amphoteric compounds like ZnO do not yeild hydronium ion on dissolving in water . I ...
5
votes
0answers
16 views

How to determine the number of water ligands attached to Pd in palladium chloride aquacomplex PdClₓ · yH₂O?

Normally this can be achieved using UV-vis: there is a strong absorbance around wavelength 220 nm which varies based on the number of ligands. If the palladium concentration is too high, the solution ...
-2
votes
1answer
27 views

important Stoichiometry question, just need formula or help and answer checking [on hold]

How many grams of Cobalt(II) chloride CoCl2 is needed to make 0.645 liters with a concentration of 1.25 Molarity and the moles are .724? (the molar mass is 129.839 I believe)
7
votes
3answers
12k views

DL vs dl notation [closed]

As the L-isomer of glucose, it is the enantiomer of the more common D-glucose. Source: Wikipedia As far as I know enantiomers or Optical isomers are non superimposable mirror image structures with ...
37
votes
2answers
4k views

Why is arsenous acid denoted H3AsO3?

Inspired by this question, I'm wondering why arsenous acid is frequently denoted $\ce{H3AsO3}$, as opposed to $\ce{As(OH)3}$, which would appear to more accurately reflect its connectivity? [edit] I ...
9
votes
1answer
2k views

The coldest (the most endothermic) reaction [closed]

What chemicals can you mix that causes the coldest (the most endothermic) reaction on a $\pu{kJ /kg}$ basis?
-2
votes
1answer
18 views

The pH scale/calculating pH level [on hold]

How much water do you need to add to 10 mL of a solution of HCl with a pH of 4 to change the pH to 5?
0
votes
0answers
13 views

Calculating 'Air Dilution' Concentration to Estimate Final Odor Intensity [on hold]

Air flows at a rate of 1 l/min into a closed 40ml flask containing 2ml of amyl acetate serially diluted to 0.000002143% v/v concentration. The air-gas mixture then has the opportunity to escape trough ...
0
votes
0answers
29 views

Effect of solid in equilibrium

CaCO3 (s) = CaO (s) + CO2 (g) We know that pure solids quantity doesn't affect the position of equilibrium. But the application of pressure in gas does. If we add CaCO3 in the closed system, the ...
8
votes
0answers
750 views

What is the chemistry behind black colour of platinum black? [closed]

Platinum is a silvery white metal and is highly unreactive then why it's powdered form "platinum black" is platinum metal but is black in colour. why would a metal such as platinum become black as a ...
3
votes
1answer
76 views

How to determine the greatest d orbital splitting?

This question comes specifically from an IB Chemistry HL Paper 1 in May 2018 TZ1, namely question 8. Which complex has the greatest d orbital splitting? It gives 4 Complexes $\ce{[Fe(H_2O)_6]^{2+}}$,...
16
votes
1answer
5k views

Failed synthesis of aspirin due to excess sulfuric acid

Last week, I tried synthesizing acetylsalicylic acid - the reaction is shown below - using $\ce{H2SO4}$ as a catalyst. However, as the title suggests the synthesis failed as I used too much $\ce{H2SO4}...
-2
votes
2answers
37 views

Heat capacity and boiling point [on hold]

Two solutions are prepared using equal moles of water, at same temperature: One contains $n$ moles of $\ce{NaCl}$ and the other contains $n$ moles of $\ce{KNO3}$. Is the heat required to raise the ...
9
votes
1answer
5k views

Will we ever run out of gold, silver, copper and other important conductors? [closed]

Conductors are very important in technology. At the current rate of extraction how long until the world's reserves of copper are depleted?
11
votes
1answer
230 views

What would happen if someone consumed a Silica Gel Packet? [closed]

Most packaged goods have the tiny Silica Gel Packets packed along with a clear warning on every single packet. My question is: What hazards of desiccant silica gel are they concerned about that it is ...
10
votes
4answers
2k views

What is the benefit of using Am-241 in smoke detectors even though it is a radioactive element? [closed]

I see the labels denoting Am-241 in my smoke detectors. I am having a hard time understand why Am-241 is used in smoke detectors even though it is a radioactive element. It seems to me like a lot of ...
15
votes
0answers
3k views

Why is nitrogen dioxide (NO2) brown? [closed]

I don't understand why nitrogen dioxide $\ce{NO2}$ is coloured brown when all of the other nitrogen oxide species and even nitrate are otherwise colorless. I understand it is due to absorption of ...
7
votes
3answers
23k views

What is the difference between enthalpy (H) and heat (q)?

It seems that in some cases it's the same (that is, $\Delta Q_p=\Delta H$) yet in others they differ. For example, \begin{align} \ce{2H2(g) + O2(g) &->2H2O(l)} & \Delta H &= -572~\...
1
vote
2answers
29 views

At what position in the distillation apparatus does the temperature match the boiling point of the distilled substance?

A student is separating $\ce{CHCl3}$ (bp = $\pu{61 ^{\circ}C}$) from $\ce{CHCl2CHCl2}$ (bp = $\pu{146 ^{\circ}C}$) by distillation. She has just begun to collect the first distillate in the receiving ...
4
votes
1answer
2k views

Why is sulfuric acid used in the Jones oxidation of alcohols?

When oxidising primary alcohols, $\ce{K2Cr2O7}$ is used because it's a useful & readily available oxidising agent. Why does the sulfuric acid need to be added? Does it have to do with the ...
0
votes
0answers
17 views

Difference between Enthalpy and Heat [on hold]

I understand that enthalpy is a state function while heat is not. But in actuality or in a potential problem how would this difference manifest itself? Also, I know that enthalpy and heat will be the ...
1
vote
0answers
66 views

What is the largest coupled cluster calculation that has ever been done (as of March 2019)? [on hold]

I am doing some research and trying to make sure the numbers I am reporting are accurate. I found that this paper says: "We were, however, able to complete a CCSDT(Q)/cc-pVTZ calculation on ...
-1
votes
0answers
16 views

Radical reactions involving terminal alkynes [on hold]

I have never seen this transformation before it isn't covered in the standard undergraduate organic chemistry so I wonder how the mechanism goes about?
2
votes
1answer
47 views

Determining the reduction potential of a half cell reaction at a given pH

$E^\circ_\ce{Cu^2+|Cu} = \pu{0.34 V}$. What will be reduction potential at $\mathrm{pH} = 14$ for the same couple? Given that $K_\mathrm{sp}$ of $\ce{Cu(OH)2}$ is $10^{-19}$. My Attempt I think ...
-1
votes
0answers
21 views

In the Joule-Thomson experiment, how is T1-T2 determined?

I figured out that H = U +PV is constant in this adiabatic condition. I am confused about the expression "T1-T2 is determined in this condition" I don't think it's an ideal gas, so delta(H) ≠ Cp ...
6
votes
2answers
117 views

How can you use ICE tables to solve multiple coupled equilibria?

If I have a problem involving multiple coupled equilibrium reactions, such as Calcium fluoride, $\ce{CaF2}$, has a molar solubility of $\pu{2.1e−4 mol L−1}$ at pH = 7.00. By what factor does its ...

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