Sodium carbonate and hydrochloric acid react according to the equation below.

\[{\text{N}}{{\text{a}}_2}{\text{C}}{{\text{O}}_3}({\text{s)}} + 2{\text{HCl(aq)}} \to {\text{C}}{{\text{O}}_2}({\text{g)}} + 2{\text{NaCl(aq)}} + {{\text{H}}_2}{\text{O(l)}}\]

Which conditions will produce the fastest initial rate with 2.0 g of powdered sodium carbonate?

A.     \({\text{100 c}}{{\text{m}}^{\text{3}}}\) of \({\text{1.0 mol}}\,{\text{d}}{{\text{m}}^{ - 3}}\) hydrochloric acid at 323 K

B.     \({\text{50 c}}{{\text{m}}^{\text{3}}}\) of \({\text{2.0 mol}}\,{\text{d}}{{\text{m}}^{ - 3}}\) hydrochloric acid at 323 K

C.     \({\text{100 c}}{{\text{m}}^{\text{3}}}\) of \({\text{1.0 mol}}\,{\text{d}}{{\text{m}}^{ - 3}}\) hydrochloric acid at 348 K

D.     \({\text{50 c}}{{\text{m}}^{\text{3}}}\) of \({\text{2.0 mol}}\,{\text{d}}{{\text{m}}^{ - 3}}\) hydrochloric acid at 348 K

Curve X on the graph below shows the volume of oxygen formed during the catalytic decomposition of a \({\text{1.0 mol}}\,{\text{d}}{{\text{m}}^{ - 3}}\) solution of hydrogen peroxide.

\[{\text{2}}{{\text{H}}_2}{{\text{O}}_2}{\text{(aq)}} \to {{\text{O}}_2}{\text{(g)}} + {\text{2}}{{\text{H}}_2}{\text{O(l)}}\]

Which change would produce the curve Y?

A.     Adding water

B.     Adding some 0.1 mol dm–3 hydrogen peroxide solution

C.     Using a different catalyst

D.     Lowering the temperature

The diagram below shows the energy changes for a reaction with and without a catalyst. Which symbols represent the activation energy, \({E_{\text{a}}}\), and the enthalpy change, \(\Delta H\), for the reaction with a catalyst?

Which statements explain why a catalyst is used in the Contact process (shown below)?

\[{\text{S}}{{\text{O}}_2}{\text{(g)}} + \frac{1}{2}{{\text{O}}_2}{\text{(g)}} \rightleftharpoons {\text{S}}{{\text{O}}_3}{\text{(g)}}\]

I.     A catalyst lowers the activation energy.

II.     A catalyst moves the position of equilibrium towards the product.

III.     A catalyst allows the same rate to be achieved at a lower temperature.

 

A.     I and II only

B.     I and III only

C.     II and III only

D.     I, II and III

Which pair of graphs shows a decomposition reaction of \(X\) that obeys first-order kinetics?