Answer : The value of Ka for acetic acid is, 
Explanation :
The chemical formula of acetic acid is, 
.
The chemical equilibrium reaction will be:
Given:
pH = 2.96
First we have to calculate the concentration of hydrogen ion.
![pH=-\log [H^+]](https://tex.z-dn.net/?f=pH%3D-%5Clog%20%5BH%5E%2B%5D)
![2.96=-\log [H^+]](https://tex.z-dn.net/?f=2.96%3D-%5Clog%20%5BH%5E%2B%5D)
![[H^+]=1.096\times 10^{-3}M](https://tex.z-dn.net/?f=%5BH%5E%2B%5D%3D1.096%5Ctimes%2010%5E%7B-3%7DM)
That means,
![[H^+]=[CH_3COO^-]=1.096\times 10^{-3}M](https://tex.z-dn.net/?f=%5BH%5E%2B%5D%3D%5BCH_3COO%5E-%5D%3D1.096%5Ctimes%2010%5E%7B-3%7DM)
![[CH_3COOH]=0.0602-(1.096\times 10^{-3})=0.0591M](https://tex.z-dn.net/?f=%5BCH_3COOH%5D%3D0.0602-%281.096%5Ctimes%2010%5E%7B-3%7D%29%3D0.0591M)
The expression for reaction is:
![K_a=\frac{[CH_3COO^-][H^+]}{[CH_3COOH]}](https://tex.z-dn.net/?f=K_a%3D%5Cfrac%7B%5BCH_3COO%5E-%5D%5BH%5E%2B%5D%7D%7B%5BCH_3COOH%5D%7D)
Thus, the value of Ka for acetic acid is,
Gold! it's boiling point is 2807 according to this chart:
http://www.lenntech.com/periodic-chart-elements/boiling-point.htm
The ansewer is Boyle’s law
The number of mole of Ca reacted is:
4.86 g Ca/ (40.08 g/mol Ca)= 0.121 mol Ca
Because Ca reacted completely with oxygen and there is 2 mol Ca, there is 1 mol O2 reacted.
Total mass of oxygen that reacted is:
0.121 mol Ca* (1mol O2/ 2 mol Ca)* (32 g O2/ 1 mol O2)= 1.94 g O2 reacted.
Hope this would help~
