20 g of sodium burned, the resulting oxide reacted with 19.6 g of sulfuric acid, determine the mass of the salt.

1) Calculate the amount of moles of sodium burned: M (Na) = 23 g / mol, n (Na) = 20/23 = 0.87 mol;
2) Determine the number of moles of sodium oxide: n (Na2O) = (1/2) * n (Na) = 0.87 * 0.5 = 0.435 mol;
3) Calculate the number of moles of sulfuric acid: M (H2SO4) = 98 g / mol, n (H2SO4) = 19.6 / 98 = 0.2 mol;
3) Sodium oxide in excess, we consider the mass of salt in terms of sulfuric acid: n (Na2SO4) = 0.2 mol, M (Na2SO4) = 142 g / mol, m (Na2SO4) = 142 * 0.2 = 28.4 g;
Answer: 28.4 g