A student prepares nitrogen dioxide gas (NO2\text{NO}_2NO2) in a school laboratory by reacting copper turnings with concentrated nitric acid (HNO3\text{HNO}_3HNO3) inside a fume cupboard.
The unbalanced chemical equation for this reaction is:
aCu(s)+bHNO3(aq)→cCu(NO3)2(aq)+dNO2(g)+eH2O(l) a\text{Cu}(s) + b\text{HNO}_3(aq) \rightarrow c\text{Cu(NO}_3)_2(aq) + d\text{NO}_2(g) + e\text{H}_2\text{O}(l) aCu(s)+bHNO3(aq)→cCu(NO3)2(aq)+dNO2(g)+eH2O(l)Which of the following rows correctly identifies the stoichiometric coefficients b b\,b and d d\,d in the balanced equation, and the key hazard classifications associated with concentrated nitric acid and nitrogen dioxide gas?
Coefficients: b=2,d=2b = 2, d = 2b=2,d=2
Concentrated HNO3\text{HNO}_3HNO3 hazards: Corrosive, Flammable
NO2\text{NO}_2NO2 hazards: Toxic, Hazardous to the environment
Coefficients: b=4,d=2b = 4, d = 2b=4,d=2
Concentrated HNO3\text{HNO}_3HNO3 hazards: Corrosive, Oxidising
NO2\text{NO}_2NO2 hazards: Toxic, Corrosive
Coefficients: b=4,d=2b = 4, d = 2b=4,d=2
Concentrated HNO3\text{HNO}_3HNO3 hazards: Flammable, Harmful
NO2\text{NO}_2NO2 hazards: Explosive, Toxic
Coefficients: b=2,d=1b = 2, d = 1b=2,d=1
Concentrated HNO3\text{HNO}_3HNO3 hazards: Corrosive, Oxidising
NO2\text{NO}_2NO2 hazards: Flammable, Harmful
230 exam-style questions on Edexcel GCSE Chemistry 1.1 Formulae, equations and hazards, covering 1.1.1 Formulae, word and balanced equations, 1.1.2 Balanced ionic equations, and 1.1.3 Hazard symbols and risk in practical work. Each one has a worked solution and a mark scheme showing where the marks go.