The titration of 25.00 mL a 0.125 M HCl
Solution required 21.37 mL of KOH to reach the endpoint.What is the concentration of the KOH?

Question

The titration of 25.00 mL a 0.125 M HCl 
Solution required 21.37 mL of KOH to reach the endpoint.What is the concentration of the KOH?

Quizplus · Accepted Answer

The balanced equation for the reaction between HCl and KOH is:

HCl + KOH → KCl + H2O

From the balanced equation, we can see that 1 mole of KOH reacts with 1 mole of HCl. Therefore, the moles of KOH used in the titration can be calculated as:

moles of KOH = (volume of KOH) x (concentration of KOH)
moles of KOH = 21.37 mL x 0.0XXX M   (Unknown Concentration)
moles of KOH = 0.XXXX

Since 1 mole of KOH reacts with 1 mole of HCl, the moles of HCl in the solution can be calculated as:

moles of HCl = (concentration of HCl) x (volume of HCl)
moles of HCl = 0.125 M x 0.02500 L
moles of HCl = 0.003125

From the balanced equation, we know that the moles of HCl used in the reaction are equal to the moles of KOH used. Therefore, we can set up an equation to solve for the concentration of KOH:

moles of KOH = moles of HCl
concentration of KOH x (volume of KOH) = concentration of HCl x (volume of HCl)
concentration of KOH = (concentration of HCl x volume of HCl) / volume of KOH
concentration of KOH = (0.125 M x 0.02500 L) / 0.02137 L
concentration of KOH = 0.146 M

Therefore, the concentration of the KOH used in the titration is 0.146 M, or choice C.

The Titration of 25