Question

The chemical equation below shows the burning of magnesium (Mg) with oxygen (O2) to form magnesium oxide (MgO).

2Mg + O2 mc009-1.jpg 2MgO

The molar mass of O2 is 32.0 g/mol. What mass, in grams, of O2 is required to react completely with 4.00 mol of Mg?
2.00

Answer 1

for every 2 mole Mg we need 1 mole O2 ( based on the equation). since there is 4 mole Mg we need 2 mole O2. one mole O2 is 32 gram so 2 mole would be 64 grams.

Answer 2

Answer: 64 grams of
`O_2` will be required to react completely with 4 moles of Mg.

Explanation: The chemical equation of burning of magnesium is given by:

`2Mg(s)+O_2(g)\rightarrow 2MgO(s)`

By stoichiometry,

2 moles of Magnesium require 1 mole of oxygen to produce 2 moles of MgO.

`\text{4 moles of Magnesium will require}=(1)/(2)* 4=2\text{ moles of }O_2`

Amount of
`O_2` required to form MgO can be calculated by:

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

Molecular mass of
`O_2=32g/mol`

`\text{Mass of }O_2\text{ required}=2moles * 32g/mol`

= 64 grams