Question

The molar mass of O2 is 32.0 g/mol. What mass, in grams, of O2 is required to reach completely with 4.00 mol of Mg

Answer 1

The reaction is as follows:

2Mg + O2 ➡️ 2MgO

Four moles of Magnesium means that the reaction can be run twice before it is depleted; two moles of O2 are required to react with this amount of Magnesium, as per the stoichiometric coefficients.

2 mol x 32 g/mol = 64 g O2 required.

Answer 2

Answer : The mass of
`O_2` required is 256 grams.

Explanation :

The balanced chemical reaction will be:

`2Mg+O_2\rightarrow 2MgO`

First we have to calculate the moles of
`O_2`.

From the balanced reaction we conclude that,

As, 2 moles of Mg react with 1 mole of
`O_2`

So, 4.00 moles of Mg react with
`4.00* 2=8.00` mole of
`O_2`

Now we have to calculate the mass of
`O_2`.

`\text{ Mass of }O_2=\text{ Moles of }O_2* \text{ Molar mass of }O_2`

Molar mass of
`O_2` = 32.0 g/mole

`\text{ Mass of }O_2=(8.00moles)* (32.0g/mole)=256g`

Therefore, the mass of
`O_2` required is 256 grams.