Question

How many grams of oxygen would be produced if 6.5g of potassium chlorate is decomposed into oxygen and potassium chlorate by heating? 2KCIO3- 3O2+2KCI

Answer 1

`2.55g`

Explanation:

Step 1: Find the molar ratio between `KClO_3` and `O_2`

The molar ratio between the two substances are `2 : 3`

This comes from the numbers in front of the equation which is the molar ratios

Step 2: Find the number of moles in `6.5g` of `KClO_3`

`n = m/M`

`n = 6.5/(39 + 35.5 + 3 \times 16)`

`n = 0.0531`

Step 3: Use the molar ratio to find number of moles of `O_2`

`n(KClO_3) = 0.0531`

`n(O_2) = 3/2\timesn(KClO_3)`

`n(O_2) = 3/2\times0.0531`

`\thereforen(O_2) = 0.07965`

Step 4: Calculate the mass of `O_2`

`n = m/M`

`0.07965 = m/(16\times2)`

`m = 0.07965\times16\times2`

`\therefore m = 2.55g`

Hope that makes sense!