Le Chatelier's principle

The second step converts nitrogen monoxide to nitrogen dioxide. $\ce{2NO(g) + O2(g) <=> 2NO2(g)}$ $\Delta H^\ominus = -114\ \mathrm{kJ\,mol^{-1}}$ (i) Identify the oxidation state of nitrogen in $\ce{NO}$ and in $\ce{NO2}$. (ii) State the equilibrium constant…

Which change would shift the position of this equilibrium towards the products? $\ce{H2(g) + I2(g) <=> 2HI(g)}$ $\Delta H = -9\ \mathrm{kJ\,mol^{-1}}$ A. Increase pressure B. Decrease pressure C. Increase temperature D. Decrease temperature

The amount of $\ce{NO2}$ prepared was checked by titration. The gas was first absorbed in water: $\ce{2NO2(g) + H2O(l) -> HNO3(aq) + HNO2(aq)}$ The resulting solution was made up to 200.0 $\mathrm{cm^3}$ in a volumetric flask, and 20.0 $\mathrm{cm^3}$ portions…

When potassium thiocyanate solution is added to a pale yellow solution containing iron(III) ions, the following equilibrium is established. $\ce{[Fe(H2O)6]^3+(aq) + SCN^-(aq) <=> [Fe(SCN)(H2O)5]^2+(aq) + H2O(l)}$ $\ce{[Fe(H2O)6]^3+(aq)}$ is pale yellow and…

The volume of the reactor containing the equilibrium mixture described in 3a is suddenly increased at constant temperature. Sketch, on the axes below, how the concentration of hydrogen changes with time until the new equilibrium is established.

Iron(III) ions and thiocyanate ions form a deep red complex ion in aqueous solution. $\ce{Fe^3+(aq) + SCN^-(aq) <=> [Fe(SCN)]^2+(aq)}$ Which of the following correctly predicts the effect of a change on this equilibrium? A. Adding iron(III) nitrate solution…

The container holding the equilibrium mixture below is compressed to half its volume while the temperature is kept constant. Which row gives the change in the amount of $\ce{PCl5}$ and the effect on the equilibrium constant, $K$?…

A sealed, rigid container holds the following gas-phase reaction at equilibrium. $\ce{N2(g) + O2(g) <=> 2NO(g)}$ $\Delta H^\ominus = +180\ \mathrm{kJ\,mol^{-1}}$ Which pair of changes would move the equilibrium position furthest towards the products? A.…

(i) Deduce the expression for the equilibrium constant, $K$, for this reaction. (ii) $0.500\ \mathrm{mol}$ each of propan-1-ol and ethanoic acid, together with a small amount of concentrated sulfuric acid, reacted at constant volume. At equilibrium,…

(i) Sketch the Maxwell–Boltzmann distribution curve for 298 K on the same axes as the 800 K curve. (ii) On the graph, annotate the position corresponding to the activation energy, $E_\mathrm{a}$. (iii) With reference to the graph, explain why a lower…

When sodium hydroxide solution is added to the water, a larger amount of bromine reacts. Explain this observation.

A student compiles data on the solubility of bromine in water at different temperatures from several websites and textbooks. Source Temperature / °C Solubility of bromine A 5 3.90 g per 100 $\mathrm{cm^3}$ of water B 15 1.15 $\mathrm{cm^3}$ of liquid bromine…

Ammonia from sweat and skin-care products reacts with HOBr to form bromamines: $\ce{NH2Br}$, $\ce{NHBr2}$ and $\ce{NBr3}$. (i) Deduce an equation for the reaction of ammonia with HOBr(aq) that produces dibromamine, $\ce{NHBr2}$(aq). (ii) The graph shows how…

Hot tubs are usually kept at 38–40 °C. Suggest two reasons why running a hot tub at a lower temperature would be better for the environment.