30mL of 0.205 M nitric acid reacts completely with 30mL of a sodium carbonate solution?

Question

what mass of sodium carbonate was contained in that solution?
help, please? it would be great if you could explain it to me!!
thanks
x

Answer 1

First write out the reaction equation:
2HNO3(aq) + Na2CO3(aq) ==> 2NaNO3(aq) + H2O + CO2(g)
It is clear that 2 moles of nitric acid reacts completely with 1 mole of a sodium carbonate.
Amount of acid: (30mL)*(0.205 M) = 6.15mMol.
Amount of carbonate to react with: 6.15mMol/2 = 3.075mMol.
Since the molar mass of carbonate is: 105.99 g/mol
Hence mass of the carbonate: (3.075mMol)*(105.99 g/mol) = 0.326 g.