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The chemical equation below shows the burning of magnesium with oxygen to form magnesium oxide 2Mg + 02 --> 2MgO the molar mass of O2 is 32.0g/mol. what mass, in grams, of O2, is required to react completely with 4.00 mol of Mg? a. 2.00 b. 64.0 c. 128 d. 256

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AbhiGhost
B.) 2Mg + 02 --> 2MgO. According to stoichiometry, 2 moles of Mg reacts with 1 mole of O2. Therefore 4 moles of Mg will react with 2 moles of O2. Therefore mass of O2 required = moles of O2 x molar mass of O2 = 2 x 32 = 64 grams.
CintiaSalazar

Answer:

The required mass of oxygen to react with 4 moles of Mg is 64 grams

Explanation:

You know the reaction where magnesium is burned with oxygen to form magnesium oxide:

2Mg + [tex]O_{2}[/tex] --> 2MgO

Oxygen is required to react completely (that is, sufficient oxygen must be present for the reaction to occur) with 4 moles of Mg. For that you observe the stoichiometry of the reaction, the amount of reagents needed. Stoichiometry in this case tells you that in order for 2 moles of Mg to react, you need 1 mole of [tex]O_{2}[/tex]. Taking this into account, you apply a rule of three: if to react with two moles of Mg you need 1 mole of [tex]O_{2}[/tex], how many moles of [tex]O_{2}[/tex] do you need to react with 4 moles of Mg?

[tex]moles of O_{2} =\frac{4 molesMg*1molO_{2} }{2 molesMg}[/tex]

moles of O_{2} =2 moles

To know the mass of [tex]O_{2}[/tex] that reacts, you must take into account the molar mass of oxygen, which is 32 grams / mol and you can apply another rule of three: if in a mole of [tex]O_{2}[/tex] there are 32 grams, how many grams are in 2 moles of oxygen?

[tex]mass of oxygen=\frac{2 moles* 32 grams}{1mol}[/tex]

mass of oxygen= 64 grams

Then, the required mass of oxygen to react with 4 moles of Mg is 64 grams