# All Questions

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### Sodium chloride + sulfuric acid [closed]

Why does sulfuric acid displace more volatile acids from salts? My textbook says that sulfuric acid can displace more volatile acids from metal salts. How is $\ce{HCl}$, which is not even a reactant, '...
661 views

### Finding partial derivatives for an ideal gas and van der Waals gas

How do I determine $\left({\partial P\over\partial V_\mathrm m}\right)_T$ for an ideal gas and also for a van der Waals gas? Note that $T$ is the only variable which is held constant, and that's my ...
1k views

### Which singlet dihalocarbene has the strongest carbon-halogen bond?

There are three singlet carbenes - difluorocarbene, dichlorocarbene and dibromocarbene. Which has the strongest carbon halogen bond? Obviously backbonding is a point to be considered, as carbene is ...
804 views

### Do vinyl cations adopt a classical or non-classical structure?

Whilst reading this question today, I remembered something that I had seen previously here. In the second linked question, @Martin provided a reference to suggest that vinyl cations actually adopt a ...
3k views

### Which of the following is the more stable carbocation?

Which of the following is the more stable carbocation? I thought the 1st carbocation would be the more stable one as the pi-electron density of phenyl group can overlap with the vacant orbital on ...
3k views

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

I don't understand why nitrogen dioxide $\ce{NO2}$ is coloured brown when nitrate $\ce{NO2-}$ and dinitrogen tetroxide $\ce{N2O4}$ are not. I understand it is due to absorption of light when its ...
1k views

### pH of bleach solution slowly decreasing?

I work within a science department in a school. We are demonstrating Universal Indicator and something odd has happened. Our bleach solution (~2.5% Sodium hypochlorite) turns blue when UI is added but ...
42k views

### What is the difference between “molecular mass”, “average atomic mass” and “molar mass”?

I don't understand the difference between "molecular mass" and "average atomic mass". They seem like the same thing to me. Is it that average atomic mass is just the weighted average of the "weights"/...
5k views

### Is melting of Tar for road construction a reversible change?

In India roads are made up of a black liquid which is prepared by melting a black material(probably coal tar). After cooling the liquid becomes very rigid. Can this solid be converted back to its ...
43k views

### Difference between reversible and irreversible processes

On a quiz, I was asked for the difference between reversible and irreversible processes. I said: For a reversible process, you can change direction at any time without disturbing equilibrium. For an ...
6k views

### Why do triple bonds have a low NMR value?

Double bonds has a positive shift compared to single bonds. It seems like that there would be a trend but then the triple bond negatively shifts, despite having great electron density similar to the ...
7k views

### Calculating molecular weight of an acid based on titration data

If $\pu{2.600 g}$ of a weak diprotic acid were dissolved in $\pu{100 mL}$ of distilled water and a $\pu{10 mL}$ aliquot of this solution required $\mathrm{21.60\ mL}$ of $\mathrm{0.1000\ M\ NaOH}$ to ...
2k views

### How are subshells and shells arranged in an atom?

If $\mathrm{2s}$ and $\mathrm{2p}$ are in the second energy level, and $\mathrm{3s}$, $\mathrm{3p}$, and $\mathrm{3d}$ are in the next (3rd) energy level, how are these subshells arranged in space in ...
299 views

### Recovery and Disposal of Unknown Copper Compound

About a month ago, I ran a small electrolysis experiment in an old fish bowl with a $\ce{MgSO4}$ electrolyte and copper electrodes. It ran for about 3-4 hours. Now, a month later, I am left with ...
3k views

### Do all conversion factors have an infinite number of significant figures?

I believe conversion factors have an infinite number of significant figures. They should be exact values; but not all of them are, are they? I looked at a pdf document (via the Internet Archive) and ...
79 views

### Understanding the energy produced from oxidizing 1 kg of lithium

I am reading the following paper in preperation for a research project on the theoretical energy density of batteries: Lithium - Air Battery: Promise and Challenges and on the second page they ...
1k views

### Water extraction of ethanol from petrol

We have now 10% ethanol mixed petrol. Seller says that if this petrol comes in contact even 10 ml of water, all ethanol which is mixed in the petrol will be extracted by water, is it true?
2k views

### Reaction of Cu in hydrochloric acid bath with exposure to air over several months?

I assume that copper will be slowly oxidized by oxygen, dissolved in water, forming copper(I) oxide (as stated here): $$\ce{4 \overset{\pm0}{Cu} + O2 -> 2 \overset{+I}{Cu}_2O}$$ Reaction rate ...
576 views

### At what temperature will 6 grams of KMnO4 saturate 100 grams of water

I am trying to obtain more $\ce{KMnO4}$ from less amount by crystallization method. If I got the temperature I would easily make the desired amount. If I am choosing the wrong method, please tell me ...
73 views

### If a conductivity meter is calibrated with aqueous standards, can it be used to measure the conductivity of an organic-based solvent system?

Trying to figure out if the calibration solutions for a conductivity probe/meter must be of a similar nature to the system which will be measured. I can only find aqueous calibration solutions online, ...
5k views

### Separation of 2 compounds ( Powder )

Suppose I have a mixture of 2 pure binary compounds, a white powder. What is the best method to separate the 2 compounds? What I have thought of so far is to dissolve powder in DI water and carry ...
372 views