800 g of sodium nitrate was dissolved in 2 liters of water. Calculate the mass fraction of sodium nitrate in the solution.

1. The density of water is 1 g / ml, we find its mass:
m (H2O) = ρ * V (H2O) = 1 * 2000 = 2000 g;
2. find the mass of the sodium nitrate solution:
m (solution) = m (NaNO3) + m (H2O) = 2000 + 800 = 2800 g;
3.Calculate the mass fraction of NaNO3:
w (NaNO3) = m (NaNO3): m (solution) = 800: 2800 = 0.2857 or 28.57%.
Answer: 28.57%.