IB Chemistry HL 2.3.3 Equilibrium Constant K Questions

Use real HL exam questions to interpret Kc magnitude, temperature effects and reciprocal or root values for transformed equilibria.

Exam points

Interpret the size of Kc to determine whether reactants or products predominate and the extent of reaction.
Explain or determine how temperature changes the value of Kc at equilibrium.
Calculate Kc for a reversed or coefficient-scaled reaction using reciprocal or root relationships.

[Maximum number: 2]

Consider the two equilibrium systems involving bromine gas illustrated below.

(a)

State the effect of increasing $\left[\mathrm{H}_{2}\right]$ in B on the value of $K_{\mathrm{c}}$ .

[ 1 ]

(b)

When bromine dissolves in water, 1 % of the original bromine molecules react according to the following equation.

\mathrm{Br}_{2}(\mathrm{aq})+\mathrm{H}_{2} \mathrm{O}(\mathrm{l}) \rightleftharpoons \mathrm{HOBr}(\mathrm{aq})+\mathrm{HBr}(\mathrm{aq})

[ 1 ]

(i)

Estimate the magnitude of $K_{\mathrm{c}}$ for this reaction. Choose your value from the following options:

[ 1 ]

$K_{\mathrm{c}}<1$ ;

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