New answers tagged concentration
4
Russell, agree with your down voting frustration but it is a common problem of any public forum. The bad news is that "simple" distinguishing test do exist, but they generate more toxic products (including a carcinogen) in a so-called iodoform test. Good for school labs only. The problem is not in distinguishing methanol versus ethanol, the problem ...
-2
It is likely that without sophisticated equipment that one cannot accurately determine methanol concentration.
That being said, my speculation on a possible process, for possible use outside of the lab, could be based on this source outline of relevant chemistry, to quote:
Methanol influences the oxidizing capacity of the atmosphere through reaction with ...
1
I think you will be better off measuring the volume change after complete burning.
A common demonstration was to place a candle in a dish of shallow water and light it, then put a clear cup over it and see how much water was sucked into the bottom as the oxygen is consumed. utilizing the same effect in a more controlled way perhaps would be a ...
0
You might get better results using titration. Pick a substance that reacts fairly completely with atmospheric oxygen, and measure how much needs to be added to remove all the $\ce{O2}$ from a known volume.
For example, you might use washed, fine, steel wool (washing is needed o remove processing oils) to remove oxygen, and methylene blue with alkaline ...
0
$HCl/H_2O$ forms an azeotrope at atmospheric pressure at ~108.6°C with an $HCl$ concentration of ~20.2%
If you try to distill your 23% mixture, you will outgass a bit of HCl as the mixture heats, thereafter you'll get constant boiling azeotrope. If you bought a pool acid or other commercial HCl mix, distilling this might be a good first step, though. They ...
1
Mike Serfas raised a very good point and it exposes the fallacy behind the concept of up vote, down vote or accepted answers. How does the OP know that the answer is "right"? There is no guarantee that the accepted answer is the right one and the down voted one is the wrong one. Since when science started relying on populism?
How can we say that ...
0
This happens because molarity is number of moles per volume of solution and molality is number of moles per mass of the solvent. Now, volume is temperature dependent property since most substances expand with increase in temp and vice versa. Hence the ratio of moles to volume change with temperature. But mass is a temperature independent property hence it ...
0
Mixing equal volumes of 0.2M $\ce{HCl}$ and 0.6M $\ce{H2SO4}$ would yield a solution with nominal concentration of 0.1M $\ce{HCl}$ and 0.3M $\ce{H2SO4}$.
Also given that $K_\mathrm{a2}$ for $\ce{H2SO4}$ is $1.2\times10^{-2}$.
RANT- I have come to absolutlye hate problems that don't use significant figures consistently. Is the initial HCl concentration ...
3
The answer given by hBy2Py is correct - "only solutions have molarity" is likely the right thing to say on the quiz. It will help you remember that in calculations of equilibrium constants and Nernst potentials, gases are referenced to a standard pressure rather than a concentration, and that pressure corresponds to 1 bar at 0 C = 1 mol / 22.7 L, ...
Top 50 recent answers are included
