Answer:
Molar mass of solute is 183.4g/mol
Explanation:
Using Raoult's law it is possible to find moles of solute, thus:
Where pressure of solution is 53.15 mmHg, pressure of pure solvent is 54.68 mmHg and mole fraction is:
53.15 mmHg = X 54.68 mmHg
<em>0.9720 = X</em>
<em />
Mole fraction of solvent is defined as moles of solvent / total moles.
Moles of solvent are:
286.8g × (1mol / 46.07g) = 6.225 moles of ethanol.
That is:
<em>Where Y are moles of solute.</em>
6.051 + 0.9720Y = 6.225
0.9720Y = 0.174
Y = 0.179 moles of solute
As mass of solute dissolved was 32.83g. Molar mass of solute is:
32.83g / 0.179mol = <em>183.4g/mol</em>
The answer is
6.8 * 10^-15
The explanation:
1- we have to convert all measurements to the same units:
Conversions:
when 1 m = 100 cm
and 1 m = 10^12 pm
So,
proton radius: 1.0*10^-13 cm * (1m / 100 cm) = 10^-15 m
proton volume: 4/3 * pi * r^3 = 4/3 * pi * (10^-15 m)^3 = 4.2 * 10^-45 cu. meters
and
H atom radius: 52.9 pm * (1m / 10^12 pm) = 5.29 * 10^-11 m
H atom volume: 4/3 * pi * r^3 = 4/3 * pi * (5.29 * 10^-11 m)^3 = 6.2 × 10^-31 cu. meters
So,
2- Fraction of space occupied by nucleus = proton volume / H atom volume
= (4.2 * 10^-45 cu. meters) / (6.2 × 10^-31 cu. meters)
= 6.8 * 10^-15
So, the "fraction" would be 6.8 * 10^-15 out of 1.
Answer:
Explanation:
Hello there!
In this case, when considering weak acids which have an associated percent dissociation, we first need to set up the ionization reaction and the equilibrium expression:
![HA\rightleftharpoons H^++A^-\\\\Ka=\frac{[H^+][A^-]}{[HA]}](https://tex.z-dn.net/?f=HA%5Crightleftharpoons%20H%5E%2B%2BA%5E-%5C%5C%5C%5CKa%3D%5Cfrac%7B%5BH%5E%2B%5D%5BA%5E-%5D%7D%7B%5BHA%5D%7D)
Now, by introducing x as the reaction extent which also represents the concentration of both H+ and A-, we have:
![Ka=\frac{x^2}{[HA]_0-x} =10^{-4.74}=1.82x10^{-5}](https://tex.z-dn.net/?f=Ka%3D%5Cfrac%7Bx%5E2%7D%7B%5BHA%5D_0-x%7D%20%3D10%5E%7B-4.74%7D%3D1.82x10%5E%7B-5%7D)
Thus, it is possible to find x given the pH as shown below:
So that we can calculate the initial concentration of the acid:
![\frac{(1.82x10^{-5})^2}{[HA]_0-1.82x10^{-5}} =1.82x10^{-5}\\\\\frac{1.82x10^{-5}}{[HA]_0-1.82x10^{-5}} =1\\\\](https://tex.z-dn.net/?f=%5Cfrac%7B%281.82x10%5E%7B-5%7D%29%5E2%7D%7B%5BHA%5D_0-1.82x10%5E%7B-5%7D%7D%20%3D1.82x10%5E%7B-5%7D%5C%5C%5C%5C%5Cfrac%7B1.82x10%5E%7B-5%7D%7D%7B%5BHA%5D_0-1.82x10%5E%7B-5%7D%7D%20%3D1%5C%5C%5C%5C)
![[HA]_0=3.64x10^{-5}M](https://tex.z-dn.net/?f=%5BHA%5D_0%3D3.64x10%5E%7B-5%7DM)
Therefore, the percent dissociation turns out to be:
![\% diss=\frac{x}{[HA]_0}*100\% \\\\\% diss=\frac{1.82x10^{-5}M}{3.64x10^{-5}M}*100\% \\\\\% diss = 50\%](https://tex.z-dn.net/?f=%5C%25%20diss%3D%5Cfrac%7Bx%7D%7B%5BHA%5D_0%7D%2A100%5C%25%20%5C%5C%5C%5C%5C%25%20diss%3D%5Cfrac%7B1.82x10%5E%7B-5%7DM%7D%7B3.64x10%5E%7B-5%7DM%7D%2A100%5C%25%20%5C%5C%5C%5C%5C%25%20diss%20%3D%2050%5C%25)
Best regards!
The vapors of some chemicals used in the chemistry laboratory, especially isocyanates, can react and bond the contact lens to the eye.
(FYI - the family of isocyanates include Superglue..I wouldn't want to have been the person who discovered this unfortunate reaction!)
Answer:
Scientific theories are testable and make falsifiable predictions. They describe the causes of a particular natural phenomenon and are used to explain and predict aspects of the physical universe or specific areas of inquiry (for example, electricity, chemistry, and astronomy).
A good theory in the theoretical sense is (1) consistent with empirical observations; is (2) precise, (3) parsimonious, (4) explanatorily broad, and (5) falsifiable; and (6) promotes scientific progress (among others; Table 1.1).
