Example:
Mass = ?
Density = 25 g/mL
Volume = 5 mL
therefore:
d = m / V
25 = m / 5
m = 25 x 5
m = 125 g
hope this helps!
A I’m sure of it because it only makes since one would think ✊
Answer:
1. pH = 1.23.
2. 
Explanation:
Hello!
1. In this case, for the ionization of H2C2O4, we can write:

It means, that if it is forming a buffer solution with its conjugate base in the form of KHC2O4, we can compute the pH based on the Henderson-Hasselbach equation:
![pH=pKa+log(\frac{[base]}{[acid]} )](https://tex.z-dn.net/?f=pH%3DpKa%2Blog%28%5Cfrac%7B%5Bbase%5D%7D%7B%5Bacid%5D%7D%20%29)
Whereas the pKa is:

The concentration of the base is 0.347 M and the concentration of the acid is 0.347 M as well, as seen on the statement; thus, the pH is:

2. Now, since the addition of KOH directly consumes 0.070 moles of acid, we can compute the remaining moles as follows:

It means that the acid remains in excess yet more base is yielded due to the effect of the OH ions provided by the KOH; therefore, the undergone chemical reaction is:

Which is also shown in net ionic notation.
Best regards!
Answer: The partial pressure of the dry oxygen is 742 torr
Explanation:
Dalton's Law of Partial Pressure states that the total pressure exerted by a mixture of gases is the sum of partial pressure of each individual gas present. Thus 
Given; Total pressure = 762 torr
partial pressure of water = 19.8 torr
partial pressure of dry oxygen = ? torr
Total pressure = partial pressure of water + partial pressure of dry oxygen
762 torr = 19.8 torr = partial pressure of dry oxygen
partial pressure of dry oxygen = 742 torr
The partial pressure of the dry oxygen is 742 torr