Consider two tanks with water, one at $25C$ and the other one at $40C.$ Each tank contains $2{10}^{-4}M$ total hypochlorite $($the sum of the HOCl and $OC{l}^{-}$concentrations$)$ and is adjusted to $pH7\mathrm{.}2.$ Given that the equilibrium constant for the dissociation of HOCl into $H^{+}$and $OC{l}^{-}$at $25C$ is $2\mathrm{.}95{10}^{-8},$ calculate the equilibrium constant at $40C.$

Consider the reaction

$CaC{O}_3(s)+2H^{+}(aq)>C{O}_2(g)+H_{2}O(l)+C{a}^{+2}(aq)$

where $CaC{O}_3$ is calcite. Following a process analogous to that taught in class, answer the following questions:

$3\mathrm{.}1$ What is $rG$ for this reaction at $25C?$

$3\mathrm{.}2$ What is $K$ at $25C?$

$3\mathrm{.}3$ What is $K$ at $40C?$

$3\mathrm{.}4$ Is the reaction exothermic or endothermic?

$3\mathrm{.}5$ If a solution has $[H^{+}]=1{10}^{-7}M,PC{O}_2={10}^{-3\mathrm{.}5}$atm, and calcite is present, what is the concentration of $C{a}^{2+}$ at equilibrium at $25C?$

Problem $4\mathrm{.}1$ and $4\mathrm{.}2$ combined. Only for Harriet, Minneapolis, Minn. and Silver Ocala, Fla.

Problem $4\mathrm{.}5.$ Estimate the activity coefficient and activity of $1\mathrm{.}0{10}^{-5}MF{e}^{3+}$ in $0\mathrm{.}01MHN{O}_3.$