Question

the pH of solution of 0.0100 mol dm3 hydrochloric acid is 2.A 10 cm3 sample of acids is measured out and distilled water added to dilute it to a total volume of 100 cm3.how do the hydrogen ion concentration and pH change as the solution is diluted

Answer 1

Calculating the moles of $HCl$ in the solution gives;

$n(HCl_{(aq)})=c(HCl_{(aq)})+V(HCl_{(aq)})$

Where $n(HCl_{(aq)})$ $=$ Moles of $HCl$

$c(HCl_{(aq)})=$ Concentration of $HCl$ in $mol/L$

$V(HCl_{(aq)})=$ Volume of the solution in $L$

Applying the formula;

$n(HCl_{(aq)})=c(HCl_{(aq)})+V(HCl_{(aq)})$

$=$ $100ml\over 1000ml$ $\times 0.100L=0.0100mol$

Diluting the solution increases it's concentration by a factor of 10 hence increasing its acidity.

Dilution of the solution further raises its PH as it increases by a factor of 10 $(1.00+1=2.00)$

In the event, the PH of the solution increases.

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