Question

How many molecules of sodium oxide will be created if 275 grams of sodium reacts with excess oxygen?

Answer 1

Answer:

• 1.34 × 10²⁴ molecules

Explanation:

To calculate the number of molecules of sodium oxide that will be created if 275 grams of sodium reacts with excess oxygen, use the chemical equation to calculate the number of moles and then multiply by Avogadro's number.

1) Balanced chemical equation (given):

• 4Na + O₂ → 2Na₂O

2) Mole ratio:

• 4 mol Na : 2 mol Na₂O

3) Calculate the number of moles in 275 g  of Na:

• n = mass in grams / molar mass
• mass of Na = 275 g
• molar mass of Na₂O = 61.9789 g/mol

• n = 275 g / 61.9789 g/mol = 4.437 mol of Na

4) Set a proportion to find the number of moles of product (Na₂O):

• 2 mol Na₂O / 4 mol Na = x / 4.437 mol Na

• x = 4.437 /  2 mol Na₂O = 2.2185 mol Na₂O

5) Convert the number of moles to number of molecules:

• # molecules = n × 6.022 × 10²³ molecules/mol = 2.2185 mol × 6.022 × 10²³ molecules/mol = 1.34 × 10²⁴ molecules (rounded to 3 significant figures).