Ammonium bromide is a crystalline solid that decomposes endothermically when heated. The reaction is
NH4Br(s) <===> NH3(g) + HBr(g).
When solid ammonium bromide is added to an evacuated flask at 300°C, which change in reaction conditions below will cause the equlibrium to shift to the right?
a. Adding more ammonia
b. Adding more ammonium bromide
c. Lowering the temperature
d. Doubling the volume of the flask
e. None of these
This is my thinking...
a. Incorrect because that would shift it the left
b. Incorrect because adding a solid to an equilibrium wont change it
c. Incorrect because since it is endothermic, lowering the temperature will make it go to the left
d. Increasing the volume won't effect it again because all 3 are not gases
This would leave me with the answer as E... though I thing that is not correct. Are one of my reasonings wrong?
You are correct about a, b, c, and e. The answer is d.
It doesn't matter that all three aren't gases. When the volume of the flask is doubled, the concentration of NH3 and HBr are halved (the solid isn't involved, of course); therefore, the reaction will shift to the right to produce more gases so that K will stay the same. (Otherwise, K would change since concentrations (or partial pressures) change.)
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