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Calculate the percent composition (out of 100) by weight of potassium in potassium carbonate decahydrate.

Sagot :

Answer:

12.26%

Explanation:

MM K = 39.1 g/mol

MM K2CO3 . 10H2O = 2x39.1 + 12.01 + 3 x 15.99 + 10 x 18.02= 318.38 g/mol

% by weight = (MM K/MM K2CO3.10H2O ) x 100= (39.1/318.8)  x 100=12.26 %

The percent composition by weight of potassium in potassium carbonate decahydrate is 13.98%

Let's represent the chemical formula of the compound as follows;

potassium carbonate decahydrate = CH₂0KO₁₃

The molecular mass of the compound can be calculated as follows:

Molecular mass of  CH₂₀KO₁₃

  • molecular mass = 12 + 20 + 39 + (16×13) = 279 g/mol

mass of potassium = 39 g

Therefore,

% mass of potassium = 39 / 279 × 100

% mass of potassium = 3900 / 279

% mass of potassium = 13.9784946237

% mass of potassium = 13.98 %

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