Question

2KCIO3 -2KCL + 302

Use the balanced chemical equation to solve the following problems. Show all work and answer with the correct units and significant figures.
a. How many moles of oxygen are produced if 4 moles of potassium chlorate decomposes?
b. If 4.5 moles of potassium chloride are produced, how many molecules of oxygen gas are also produced?
c. If 5.0 g of potassium chlorate decomposes, how many grams of potassium chloride are produced?

Answer 1

a. 6 moles of O₂

b. 4.06×10²⁴ molecules of O₂

c. 3.04 g of KCl

Step-by-step explanation:

Reaction of decomposition is:

2KClO₃ → 2KCl + 3O₂

a. See stoichiometry value

2 moles of potassium chlorate can decompose to 2 moles of potassium chloride and 3 moles of oxygen. Ratio is 2:3

If 2 moles of KClO₃ can decompose to 3 moles of O₂

Then 4 moles, may decompose to (4 . 3)/2 = 6 moles of O₂

b. In this case, the stoichiometry is the same.

Per 2 moles of KClO₃, I produce 2 moles of KCl

Then, 4.5 moles of KCl, were produced by 4.5 moles of KClO₃

We apply, the last relation:

(4.5 . 3) /2 = 6.75 moles of O₂ are also produced.

How many molecules are in 6.75 moles?

6.75 mol . 6.02×10²³ molecules/mol = 4.06×10²⁴ molecules of O₂

c. First of all, we convert the mass to moles:

5g . 1mol /122.55g = 0.0408 moles of salt

As ratio is 2:2, 0.0408 moles of salt, decompose to 0.0408 moles of KCl

We convert the moles to mass: 0.0408 mol . 74.55g /mol = 3.04g