Potassium was placed in 72 g of water. Calculate the mass of potassium hydroxide formed

| May 14, 2021 | education

Potassium was placed in 72 g of water. Calculate the mass of potassium hydroxide formed and the volume of hydrogen released.

Let’s find the amount of water substance by the formula:

n = m: M.

M (H2O) = 18 g / mol.

n = 72 g: 18 g / mol = 4 mol.

Let’s compose the reaction equation, find the quantitative ratios of substances.

2K + 2H2O = 2KOH + H2.

According to the reaction equation, there is 1 mole of hydrogen per 2 mol of H2O. Substances are in quantitative ratios of 2: 1.

The amount of hydrogen substance will be 2 times less than H2O.

n (H2) = ½ n (H2O) = 4: 2 = 2 mol.

Let’s find the volume of hydrogen.

V = Vn n, where Vn is the molar volume of gas, equal to 22.4 l / mol, and n is the amount of substance.

V = 2 mol × 22.4 L / mol = 44.8 L.

Let’s find the mass of KOH.

n (H2O) = n (KOH) = 4 mol.

Let’s find the mass of KOH.

m = n × M.

M (KOH) = 56 g / mol.

m = 56 g / mol × 4 mol = 224 g.

Answer: 224 g; 44.8 l.



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