Question

4. Use the chemical equation to answer the question.
4K(s) + O2(g) → 2K2O(s)
The molar mass of potassium (K) is 39 g/mol. The molar mass of oxygen (O) is 16 g/mol. How many grams of potassium are needed in the reaction to produce 23.5 grams of potassium oxide (K2O)?

A 23.5 g
B 9.75 g
C 0.50 g
D 19.5 g

Answer 1

The amount, in grams, of potassium that would be needed to produce 23.5 grams of potassium oxide will be 19.5 grams

Stoichiometric calculation

From the equation, the mole ratio of K to K2O is 2:1.

Mole of 23.5 K2O = mass/molar mass

Molar mass of K2O = 39x2 + 16 = 94

Mole of 23.5 K2O = 23.5/94 = 0.25 moles

Equivalent mole of K = 0.25 x 2 = 0.5 moles

Mass of 0.5 mole K = 0.5 x 39 = 19.5 grams

More on stoichiometric calculations can be found here: https://brainly.com/question/8062886

Answer 2

Answer: Calculating mass quick check

1. The mass of the reactants must be equal to the mass of the products. The total number of moles of the reactants can be more or less than the total number of moles of the products.

2. Divide the mass of the reactant by its molar mass to find the number of moles of the reactant. Use the chemical equation to find the number of moles of the product. Multiply the number of moles of the product by its molar mass to find the mass of the product.

3. 2(108 g/mol)+32 g/mol=248 g/mol; (248 g/mol)(0.02 mol)=4.96 g

4. 19.5 g

5. 853.5 g

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