Question

Calculate the empirical formula for each of the following substances.

Part A 2.90 g of Ag and 0.430 g of S Express your answer as a chemical formula.

Part B 2.22 g of Na and 1.55 g of S Express your answer as a chemical formula.

Part C 4.22 g of Na, 2.94 g of S, and 5.86 g of O Express your answer as a chemical formula.

Part D 1.84 g of K, 0.657 g of N, and 2.25 g of O

Calculate the empirical formula of each compound from the percent composition.

Part A 5.13 g of Cr and 2.37 g of O Express your answer as a chemical formula. Part B 2.82 g of K, 0.870 g of C, and 2.31 g of O Express your answer as a chemical formula. Part C 86.0 %Cu and 14.0 %P Express your answer as a chemical formula. Part D 25.9 %N and 74.1 %O Express your answer as a chemical formula.

Answer 1

Part A)

2.90 g of Ag and 0.430 g of S

Calculate atomic ratio by dividing g composition by atomic mass.

Mass ratio of Silver =2.9 /107.86 = 0.026

Mass ratio of Sulfur = 0.430/32.06 = 0.013

Now calculate simplest ratio by dividing atomic ratio by smallest atomic ratio

Simplest ratio of Silver = 0.026/0.013 = 2

Simplest ratio of Sulfur = 0.013/0.013 = 1

Empirical formula of compound = Ag₂S

Part B)

2.22 g of Na and 1.55 g of S

Calculate atomic ratio by dividing g composition by atomic mass.

Mass ratio of Sodium =2.22 /22.99 = 0.096

Mass ratio of Sulfur = 1.55/32.06 = 0.048

Now calculate simplest ratio by dividing atomic ratio by smallest atomic ratio

Simplest ratio of Silver = 0.096/0.048 = 2

Simplest ratio of Sulfur = 0.048/0.048 = 1

Empirical formula of compound = Na₂S

Part C)

4.22 g of Na, 2.94 g of S, and 5.86 g of O

Calculate atomic ratio by dividing g composition by atomic mass.

Mass ratio of Sodium = 4.22/22.99 = 0.18

Mass ratio of Oxygen = 5.86 /16 = 0.36

Mass ratio of Sulfur = 2.94/32.06 = 0.09

Now calculate simplest ratio by dividing atomic ratio by smallest atomic ratio

Simplest ratio of Silver = 0.18/0.09 = 2

Simplest ratio of Sulfur = 0.09/0.09 = 1

Simplest ratio of Oxygen = 0.36/0.09 = 4

Empirical formula of compound = Ag₂SO₄

Part D)

1.84 g of K, 0.657 g of N, and 2.25 g of O

Calculate atomic ratio by dividing g composition by atomic mass.

Mass ratio of Potassium = 1.84/39.09 = 0.047

Mass ratio of Nitrogen = 0.657/14 = 0.047

Mass ratio of Oxygen = 2.25/16 = 0.14

Now calculate simplest ratio by dividing atomic ratio by smallest atomic ratio

Simplest ratio of Potassium = 0.047/0.047 = 1

Simplest ratio of Nitrogen = 0.047/0.047 = 1

Simplest ratio of Oxygen = 0.14/0.047 = 2.98 approx = 3

Empirical formula of compound = KNO₃