Chemistry Question

Question

What volume of 0.150 M HCl is required to neutralize 100 mL 0.050 M KOH?

1. A. 0.75 mL
2. B. 0.033 mL
3. C. 300 mL
4. D. 33 mL

Answer 1

Hello, Ronielien,

The balanced equation for this reaction is HCl + KOH = KCl + KOH.

We need this to determine the ratio of acid and base to achieve neutralization. For every mole of HCl we need one mole of KOH. Molar, the concentration, is defined as moles per liter. We have 100 ml of 0.050M KOH - we need to know how many moles that is. First note that M is defined with the unit liter, but the KOH is in ml. Convert ml into liters by dividing by 1000, so we have 0.1 liter KOH. To find the number of moles:

(0.1L KOH)*(0.05 moles KOH/Liter) = .005 moles KOH

The balanced equation tells us we need 0.005 moles of HCl to completely react with 0.005 mole of KOH. The HCl concentration is 0.15 moles/Liter. If we set X to the amount of 0.15 M HCl we need, we can make the following equation:

(0.15 moles HCl/Liter)* X = 0.005 moles HCl

Solve for X to get 0.0333 Liters of HCl. Divide by 1000 to get ml, 33.3 ml. Make that 33 ml with 2 sig figs.

Bob