Assignment 1
Question 1:
The pOH of a sample of backing soda dissolved in water is 5.74 at 25°C.
Calculate the pH, [H+] and [OH-] for this sample.
Is the solution acidic or basic?
Question 2:
Calculate the pH in each of the following:
a) 0.005 M HNO3
b) 0.6 M KOH
c) 0.25 M CH3COOH (Ka = 1.8x10-5)
d) 2M NH3 (Kb= 1.8x10-5)
e) 0.2M Arsenic acid (H3AsO4) ( Ka1 = 5 x 10-3 ,Ka2 = 8x10-8,Ka3 = 6x10-10)
Question 3:
Determine the percent dissociation of formic acid HCOOH in a 2M solution. (Ka= 1.77 x10-4)
Question 4:
Given the Ka value for acetic acid is 1.8 x 10-5 and the Ka value for hypochlorous (HOCl) acid is
3.5 x 10-8. Which is the stronger base, OCl- or CH3COO- ?
Question 5:
The pH of a sample of human blood was measured to be 7.41 at 25°C. Calculate pOH, [H +]
and [OH-] for the sample.
Extra Questions:
1- In a 1.00M solution of HF, the percent dissociation is 8.1%. Calculate Ka.
2- Calculate the concentration of an aqueous KOH solution that has pH=10.50 .
3- Arsenic acid (H3AsO4) is a triprotic acid with ( Ka1 = 5 x 10-3 ,Ka2 =8x10-8,Ka3 = 6x10-10 ).
Calculate the concentration of [HAsO42-] in a 0.20 M arsenic acid.