Studying for Regionals

[chrishuff]

Does anybody know how to solve this problem?

At some temperature, Kc= 171 for the dimerization of NO2. If 2.887 moles of the dimer are injected into a closed 2.00 liter container at this temperature, what will be the equilibrium concentration of the dimer?

Answer: 1.40 M

[Salvadoramerican]

I believe you set it up like like this [unparseable or potentially dangerous latex formula] then [unparseable or potentially dangerous latex formula] plug in 171 for [unparseable or potentially dangerous latex formula] then since the dimer is place in the container then it might shift to the reactants so where given the molarity of the dimer so now [unparseable or potentially dangerous latex formula] and we solve to get x and subtract it from the given molarity to get [unparseable or potentially dangerous latex formula]

[chrishuff]

Can you explain why we subtract it from the given molarity?

(2.887/2) = M

M - 0.0890002863 is roughly equal to 1.36, which rounds up to 1.4

[Salvadoramerican]

Well since we are moving it to a new container the equillibrium shifts in reverse so it'll shift to the reactants, so the molarity would decrease to regain equillibrum, because of that we subtract the amount the reactants gain from the dimer

[chrishuff]

It's making sense to me. Thanks! I guess with what me and my science coach went through the past couple of weeks, mistakes can happen with relatively simple problems like these.