A solution of hydrochloric acid has a concentration of 1.0 mol / L. If 10 mL of this acid is added to water and made up to a total volume of 1.0 L, what is the pH of the resulting solution?
A. 9
B. 2
C. 5
D. 6
E. 0
We are told we have HCl which is a strong acid, so we can use the simplest pH calculation equation: pH = -log[H^+]
You should know what log$0$ is and log$1$, and know what happens if there is a decimal of 1, for example, log$0.1$.
Initial pH: 1.0M = 0
If we are diluting the solution by adding 10mL to water in order to have a total volume of $1.0$L, we are diluting by a factor of 100. This means that we will have (1/100)M in the litre solution. With this, we can calculate the pH:
pH calculations
1.0M = 0
0.1M = 1
0.01M = 2
\fcolorbox{red}{grey!30}{Therefore the answer is B, $2$.}
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