Titrations

A solution of hydrochloric acid is made by dissolving hydrogen chloride gas in 100.0 cm3 water . This solution neutralises a 15.0 cm3 sample of 0.10 moldm-3 sodium carbonate solution.

a) What mass of hydrogen chloride gas was dissolved in 100.0 cm3 of water ?
b) What volume of hydrogen chloride was this?

Reply 1

TypicalNerd

Original post

by gIock

A solution of hydrochloric acid is made by dissolving hydrogen chloride gas in 100.0 cm3 water . This solution neutralises a 15.0 cm3 sample of 0.10 moldm-3 sodium carbonate solution.
a) What mass of hydrogen chloride gas was dissolved in 100.0 cm3 of water ?
b) What volume of hydrogen chloride was this?

Part (a):

The starting point should be calculating the moles of Na2CO3 since you have both the volume and concentration of the solution.

Next, you will need to refer to the equation for the reaction of Na2CO3 and HCl

e.g Na2CO3 + 2HCl —> 2NaCl + CO2 + H2O

From this and the number of moles of Na2CO3, you can deduce the moles of HCl that must have reacted.

How might the moles be useful for calculating the mass?

Part (b):

There isn’t a lot of information given here, but presumably they are expecting you to assume that the HCl gas dissolved in water was under room temperature and pressure.

If so, do you know what the molar volume of a gas at room temperature and pressure is and how it might be useful?