Question

Complete the changes in concentrations (or pressure, if requested) for each of the following reactions.

Short answer

a)

2H2(g) + O2 (g) ⇌ 2H2O (g)
Change in concentration	-2X	-X	+2X
Change in concentration	-1.50M	1.50M/2 =0.75M	1.50M

b)

CS2 (g) +4H2(g)⇌ CH4 (g) 2H2S(g)
Change in concentration	\[{\rm{+x}}\]	\[+4{\rm{x}}\]	\[-{\rm{x}}\]	\[-2{\rm{x}}\]
Change in concentration	\[0.020{\rm{M}}\]	\[0.020M\cdot4=0.080{\rm{M}}\]	\[-0.020{\rm{M}}\]	\[-0.020M \cdot 2=-0.040{\rm{M}}\]

c)

H2 (g) + cl2 (g)⇌ 2HCl (g)
Change in concentration	+x	+x	-2x
Change in concentration	1.50M	1.50M	-1.50M.2=-3.00M

d)

2NH3(g) + 2O2(g)⇌ N2O (g) 3H2 O(g)
Change in concentration	\[-\frac{{2x}}{3}\]	\[-\frac{{2x}}{3}\]	\[+\frac{x}{3}\]	\[+x\]
Change in concentration	\[-\frac{{60.6{\rm{\;torr\;}}2}}{3}=-40.4{\rm{\;torr\;}}\]	\[-\frac{{60.6{\rm{\;torr\;}}\cdot 2}}{3}=-40.4{\rm{\;torr\;}}\]	\[+\frac{{60.6{\rm{\;torr\;}}}}{3}=+20.2{\rm{\;torr\;}}\]	\[60.6{\rm{\;torr\;}}\]

e)

NH4HS(s)⇌ NH3 (g) + H2S (g)
Change in concentration		\[+{\rm{x}}\]	\[+x\]
Change in concentration		\[9.8\cdot{10^{-6}}{\rm{M}}\]	\[9.8\cdot{10^{-6}}{\rm{M}}\]

f)

Fe(S) + 5CO(g)⇌ Fe(CO)4(g)
Change in concentration		\[{\rm{ - 5x}}\]	\[ + x\]
Change in concentration		\[ - 0.012{\rm{atm}} \cdot 5 = - 0.06{\rm{atm}}\]	\[0.012{\rm{atm}}\]

Step-by-step solution

Definition of change in concentration

The rate of a chemical reaction is defined as the rate of change in concentration of a reactant or product divided by its coefficient from the balanced equation.