If 23.0 grams of magnesium is burned in an atmosphere containing excess oxygen gas, how many grams of the magnesium oxide will be formed? Equation: 2Mg+O2--->2MgO

1 Answer
Feb 20, 2018

#38.4 \ "g"# of magnesium oxide

Explanation:

We first need to write down the balanced equation, that is

#2Mg+O_2->2MgO#

Here, the mole ratio between #Mg# and #MgO# is #2:2=1#. Since we have used #23 \ "g"# of magnesium, we have to convert that amount into moles of magnesium.

Magnesium has a molar mass of #24 \ "g/mol"#. So, in #23 \ "g"# of magnesium, there exists

#(23cancel"g")/(24cancel"g""/mol")~~0.96 \ "mol"# of magnesium

Since the mole ratio between magnesium and magnesium oxide is #1#, then #0.96# moles of magnesium oxide will be produced.

Magnesium oxide has a molar mass of #40 \ "g/mol"#. So, #0.96# moles of magnesium oxide will have a mass of

#0.96cancel"mol"*40"g/"cancel"mol"=38.4 \ "g"#

So, #38.4# grams of magnesium oxide will be formed.