Calculate what mass of metallic sodium needs to be dissolved in water in order to obtain a 10%

Calculate what mass of metallic sodium needs to be dissolved in water in order to obtain a 10% sodium hydroxide solution by mass 150 g.

1. Let’s compose the equation of the chemical reaction:

2Na + 2H2O = 2NaOH + H2.

2. Find the chemical amount of sodium hydroxide released:

m (NaOH) = m (solution) * ω (NaOH) / 100% = 150 g * 10% / 100% = 15 g.

n (NaOH) = m (NaOH) / M (NaOH) = 15 g / 40 g / mol = 0.375 mol.

3. According to the reaction equation, we find the chemical amount, and then the mass of the required sodium:

n (Na) = n (NaOH) = 0.375 mol.

m (Na) = n (Na) * M (Na) = 0.375 mol * 23 g / mol = 8.625 g.

Answer: m (Na) = 8.625 g.