Answer to Question #138125 in General Chemistry for BRIANNA SMITH

Question

125ml of 1.00M HCl is added to 100ml of 1.00M NaOH. What is the pH of the resulting solution? (Please show your work.)

Answer 1

Millimoles of $HCl= 125\times 1.00= 125$

Millimoles of $NaOH= 100\times 1.00= 100$ Sodium hydroxide reacts with hydrochloric acid in equal amount. So, $100$ millimoles will be neutralised of both reactants.

So , $25$ millimoles of $HCl$ will remain unreacted .

So moles of $H^+$ in solution will be $25\times 10^{-3}= 0.025$

Total volume of solution $= 125+100 \ ml = 225 \ ml$

Concentration of $H^+ = \frac{0.025}{225\times 10^{-3}}=0.11\ M$

$pH$ of solutiob$=-log[H^+] = -log(0.11) = 0.95$