Find the mass of salt that is formed by the interaction of 400 g of a 25% potassium hydroxide solution with carbon dioxide.

| March 1, 2021 | education

Find the mass of potassium hydroxide in the solution.

The mass fraction of a substance is calculated by the formula:

W = m (substance): m (solution) × 100%,

m (substance) = (m (solution) × W): 100%,

m (substance) = (400 g × 25%): 100% = 100 g.

Find the amount of potassium hydroxide substance by the formula:

n = m: M.

M (KOH) = 56 g / mol.

n = 100 g: 56 g / mol = 1.79 mol.

2. Let’s compose the reaction equation, find in what quantitative ratios the substances are.

2 KOH + CO2 = K2CO3 + H2O.

For 2 mol of potassium hydroxide there is 1 mol of potassium carbonate. The substances are in quantitative ratios of 2: 1.

The amount of the salt substance will be 2 times less than that of potassium hydroxide.

n (K2CO3) = 1 / 2n (KOH) = 1.79: 2 = 0.895 mol.

Find the mass of potassium carbonate.

m = n × M,

M (K2CO3) = 2 × 39 + 12 + 48 = 138 g / mol.

m = 0.895 mol × 138 g / mol = 123.51 g.

Answer: m = 123.51 g.



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