Question

Problem #4: Interpret reactions in terms of representative particles, then write balanced chemical

equations and compare with your results. Determine limiting and excess reagent and the amount of
unreacted excess reactant.
a) 3 atoms of carbon combine with 4 molecules of hydrogen to produce methane (CH4)
b) 7 molecules of hydrogen and 2 molecules of nitrogen gases react to produce ammonia
c) 4 molecules of hydrogen and 5 molecules of chlorine react.

Answer 1

a) The balanced chemical equation for the reaction is:

3C (s) + 4H2 (g) → CH4 (g)

In this reaction, 3 carbon atoms combine with 4 molecules of hydrogen to produce one molecule of methane. The representative particles in this reaction are atoms of carbon and molecules of hydrogen and methane.

b) The balanced chemical equation for the reaction is:

2N2 (g) + 7H2 (g) → 2NH3 (g)

In this reaction, 7 molecules of hydrogen react with 2 molecules of nitrogen gas to produce 2 molecules of ammonia. The representative particles in this reaction are molecules of hydrogen, nitrogen, and ammonia.

c) The balanced chemical equation for the reaction is:

H2 (g) + Cl2 (g) → 2HCl (g)

In this reaction, 4 molecules of hydrogen react with 5 molecules of chlorine gas to produce 10 molecules of hydrogen chloride. The representative particles in this reaction are molecules of hydrogen, chlorine, and hydrogen chloride.

To determine the limiting and excess reagents and the amount of unreacted excess reactant, we need to know the initial amounts of each reactant. Without this information, we cannot determine the limiting and excess reagents or the amount of unreacted excess reactant.