500
A student was titrating a 15.00 mL sample of HCl with Ca(OH)2. To reach the endpoint of the titration
and neutralize all of the HCl, the student added 49.62 mL of 0.00150 M Ca(OH)2. Write a balanced
equation for this titration. How many moles of Ca(OH)2 did the student add? How many moles of HCl
were present in the sample? What was the concentration (in M) of HCl in the sample?
2 HCl + Ca(OH)2 -----> CaCl2 + 2H2O
Moles of Ca(OH)2: 49.62 mL *1L
1000mL
= 0.04962 L
0.04962 L * 0.00150 mol/L
= 7.44 x 10-5 mol Ca(OH)2
Moles of HCl: 7.44 x 10-5 mol Ca(OH)2 * 2 mol HCl
1molCa(OH) 2
= 1.49 x 10-4 mol HCl
Concentration of HCl: 15.00 mL * 1L
1000 mL
= 0.01500 L,
0.01500 L
1.49 x 10 mol -4/0.01500 L
= 9.92 x 10-3 mol/L HCl