Question
Chemistry Question on Bohr’s Model for Hydrogen Atom
The pH of a 10 ml aqueous solution of HCl is 4. The amount of water to be added to this solution in order to change its pH from 4 to 5 is:
A
(A) 30 ml
B
(B) 60 ml
C
(C) 90 ml
D
(D) 120 ml
Answer
(C) 90 ml
Explanation
Solution
Explanation:
On dilution, milli equivalent of the solute remains constant.Intially pH of HCl=4So, normality of HCl=10−4 NAfter dilution pH of HCl=5So, normality of HCl will be =10−5 NN1V1=N2V210−4×10=10−5×VV=100 mLSo, the amount of water to be added to this solution in order to change its pH from 4 to 5 is =100−10=90Thus, 90 mL of water should be added for this pH change.Hence, the correct option is (C).