Question

If 46 grams of O2 reacts, calculate the moles of CO2 produced. CH4 + 2O2—> CO2 +2H2O

Answer 1

To answer this, we can start at the end and see what we need to calculate it.

We want the number of moles of CO₂ produced. From the chemical equation, we can see that the coefficient of O₂ is 2 and of CO₂ is 1, so wwe need to apply thsi stoichiometry:

CO₂ --- O₂

1 --- 2

`\begin{gathered} (n_(CO_2))/(1)=(n_(O_2))/(2) \\ n_(CO_2)=(n_(O_2))/(2) \end{gathered}`

The number of moles of O₂ can be calculated from the mass o O₂ and its molar mass:

`\begin{gathered} M_{O_(2)}=\frac{m_(O_2)}{n_{O_(2)}} \\ n_{O_(2)}=\frac{m_(O_2)}{M_{O_(2)}} \\ n_{CO_(2)}=(n_(O_2))/(2)=\frac{m_(O_2)}{2M_{O_(2)}} \end{gathered}`

We already have the mass of O₂, but we need to calculate its molar mass:

`M_(O_2)=2\cdot M_O=2\cdot15.9994g/mol=31.9988g/mol`

Now, substituting the values, we have:

`n_(CO_2)=\frac{m_{O_(2)}}{2M_{O_(2)}}=(46g)/(2\cdot31.9988g/mol)=(23)/(31.9988)mol=0.7187\ldots mol\approx0.72mol`

So, the number of moles of CO₂, assuming complete reaction, is approximately 0.72 mol.