Back titration exercise 1

A 0.723 g sample of chalk (largely calcium carbonate) was dissolved in 20.0 cm³ of 1.00 M hydrochloric acid. When the reaction was complete, the remaining acid was titrated with 0.500 M sodium hydroxide solution. The titre was 12.00 cm³.

What would be used to measure out the 20.0 cm³ of hydrochloric acid?

What feature of the first reaction between the acid and the chalk could lead to an error and how could this be avoided?

Assuming only the calcium carbonate reacts with the acid, what percentage of the chalk sample is calcium carbonate?

Solution to exercise