Ap Chem equations and reactions summary

Question

A sample of impure sodium hydroxide with a mass of 3.674 grams is completely dissolved in deionized water to a volume of 250.0 mL. A 10.00 mL portion of the sample is titrated with a 0.01100 M solution of hydrochloric acid. When 11.25 mL of the acid has been added, a sharp color change is observed indicating the endpoint.

c. Write a complete, balanced chemical equation for the reaction between sodium hydroxide and hydrochloric acid.

d. Calculate the percent by mass of sodium hydroxide in the original, impure sample.

Answer 1

The complete balanced equation is:

NaOH +HCl= NaCl+ H2O

Strength of NaOH = (0.011×11.25/10 ) M

=0.0123 M

250 ml of 0.0123 M NaOH equals to : (250×0.0123×40/1000) g =0.123 g

purity= (0.123/3.674) ×100

= 3.34%