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Which of the following ratios are needed to determine the mass of oxygen produced from the decomposition of 10 grams of potassium chlorate? Select all that apply.

Which of the following ratios are needed to determine the mass of oxygen produced-example-1

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Answer:

1 mole KClO3 / 122.55 g KClO3,

3 mole O2 / 2 mole KClO3,

31.998 g O2 / 1 mole O2.

Step-by-step explanation:

First, let's convert 10 g of KClO3 to moles using the molar mass of KClO3 which is 122.5 g/mol:


10\text{ g KClO}_3\cdot\frac{1\text{ mol KClO}_3}{122.5\text{ g KClO}_3}=0.082\text{ moles KClO}_3.

Now you can see in the chemical equation that 2 moles of KClO3 reacted produces 3 moles of O2, so we state a rule of three to find the number of moles of O2:


\begin{gathered} 2\text{ mole KClO}_3\rightarrow3\text{ mole O}_2 \\ 0.082\text{ moles KClO}_3\rightarrow?\text{ mole O}_2 \end{gathered}

The calculation of this will look like this:


0.082\text{ mole KClO}_3\cdot\frac{3\text{ mole O}_2}{2\text{ mole KClO}_3}=0.12\text{3 moles O}_2.

The final step to finding the mass of oxygen (O2) is using its molar mass which is 32 g/mol, like this:


0.123\text{ mole O}_2\cdot\frac{32\text{ g O}_2}{1\text{ mol O}_2}=3.94\text{ g O}_2.

As you can see from this process, the needed ratios are:

1 mole KClO3 / 122.55 g KClO3,

3 mole O2 / 2 mole KClO3,

31.998 g O2 / 1 mole O2. (in the explanation is approximated)

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