Question

10 ml of a solution having ph =4 is added with 990 ml of 0.1M NaCl solution. PH of resulting solution is (1) 4 (2) 5.5 (3) 6 (4) 6.5

Answer 1

6.

H+ conc has become 100 times lower ( 1000ml from 10ml). Log 100 is 2. Add to initial ph. This is only shortcut. This can also be done by calculating with procedure.

Answer 2

Answer:

3) 6

Explanation:

Ph = -  log p Ka

4 = - log p Ka

[ H+] =  10⁻⁴ mol/ l

C = 10⁻⁴ / (990 + 10) = 10⁻⁶ mol/l

Ph = -  log p Ka

Ph = -  log 10⁻⁶

Ph = 6

Hence the ph of the solution is 6.