Question

Magnesium nitrate, Mg(NO3)2, will decompose when heated to give a white solid and a mixture of

gases. One of the gases released is an oxide of nitrogen, X.
7.4g of anhydrous magnesium nitrate is heated until no further reaction takes place.
What mass of X is produced?
B 2.3g
C 3.05
D 4.6g​

Answer 1

Mass of X produced : D. 4.6 g

Further explanation

Reaction

Decomposition of Magnesium nitrate into Magnesium oxide, Oxygen, and Nitrogen oxides

2 Mg(NO₃)₂ → 2 MgO + 4 NO₂ + O₂

mol Magnesium nitrate-Mg(NO₃)₂(MW=148,3 g/mol) :

`\tt (7.4)/(148.3)=0.05`

mol ratio Mg(NO₃)₂ : NO₂ = 2 : 4, so mol NO₂ :

`\tt (4)/(2)* 0.05=0.1`

mass NO₂(MW=46 g/mol) :

`\tt 0.1* 46~g/mol=4.6~g`

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