Answer:
Volume of water that must be added is 1.10 L
Explanation:
pH measures the acidity or the alkalinity of a substance
It is given by;
pH = -log[H+]
Using this we can find the concentration of H+ ions in the acid
pH = 2 = -log[H+]
Therefore;
[H+] = 10^-2
= 0.01 M
But, since 1 mole HNO₃ ionizes to give 1 mole of H+, then the concentration of HNO₃ is equal to the concentration of H+ ([HNO₃] = [H+])
Therefore;
Initial [HNO₃] = 0.01 M
Initial volume of HNO₃ = 11.1 mL or 0.0111 L
We can then use dilution equation to find the final volume after dilution.
The final pH is 4
Therefore, [H+] = 10^-4
= 0.0001 M
Thus, the final concentration of HNO₃ is 0.0001 M
Using dilution equation;
M1V1 =M2V2
Thus; V2 = M1V1÷ M2
= (0.01 M× 0.0111 L)÷ 0.0001 M
= 1.11 L
This means the final total volume will 1.11 L or 1110 ml
Therefore; The volume of water added = 1110 ml - 11.1 ml
= 1098.9 ml or
= 1.0989 L
= 1.10 L(2 d.p.)
Hence, The volume of water that must be added is 1.10 L
