WACE Chemistry Unit 3 equilibrium, acids and bases, and redox: exam-style practice quiz

Both rates increase by the same factor, so the ammonia yield and Kc are unchanged

Both rates increase, the reverse rate more, so the ammonia yield falls and Kc decreases

Only the forward rate increases, so the ammonia yield rises and Kc increases

Both rates increase, the forward rate more, so the ammonia yield rises and Kc is unchanged

The brown colour darkens at once, then fades partly, but ends darker than at the start

The brown colour fades at once and ends paler than it was at the start of the experiment

The brown colour darkens at once and then stays at that new darker shade from then on

No change in colour is seen, because the value of Kc is unchanged by the change in volume

$K_c = \dfrac{2[\text{SO}_3]}{2[\text{SO}_2][\text{O}_2]}$

$K_c = \dfrac{[\text{SO}_2]^2[\text{O}_2]}{[\text{SO}_3]^2}$

$K_c = \dfrac{[\text{SO}_3]^2}{[\text{SO}_2]^2[\text{O}_2]}$

$K_c = \dfrac{[\text{SO}_3]^2}{[\text{SO}_2]^2 + [\text{O}_2]}$

At equilibrium the mixture is mostly reactants, with very little product

At equilibrium the mixture is mostly products, with very little reactant

The reaction happens extremely slowly, taking a long time to reach equilibrium

The forward reaction must be strongly endothermic at this temperature

The forward rate increases more than the reverse rate, so more product forms

The equilibrium shifts towards the side with the lower activation energy

Both rates increase, so Kc increases while the concentrations stay the same

The forward and reverse rates increase equally, so concentrations and Kc do not change

$\text{HCO}_3^-$ acts as a base, and its conjugate acid is $\text{H}_2\text{CO}_3$

$\text{HCO}_3^-$ acts as an acid, and its conjugate base is $\text{CO}_3^{2-}$

Water acts as a base, and its conjugate acid is $\text{OH}^-$ in this reaction

$\text{HCO}_3^-$ acts as a base, and its conjugate acid is $\text{OH}^-$

12.7

13.0

1.0

13.3

2.02

3.0

4.0

7.0

Sodium ions react with the added chloride ions, so the pH does not change at all

Ethanoic acid reacts with the added hydronium ions, so the pH rises a little

The added hydronium ions ionise more ethanoic acid, so the pH falls sharply

Ethanoate ions react with most of the added hydronium ions, so the pH falls only slightly

The cell potential is 0.04 V and zinc is the negative anode

The cell potential is 1.56 V and zinc is the negative anode

The cell potential is 1.56 V and silver is the negative anode

The cell potential is 2.36 V and zinc is the positive cathode

0.123 mol L$^{-1}$

0.0813 mol L$^{-1}$

0.246 mol L$^{-1}$

0.0615 mol L$^{-1}$

A pink-brown solid forms on the anode and colourless gas bubbles form at the cathode

Colourless gas bubbles form at both electrodes and the blue colour deepens over time

A pink-brown solid forms on the cathode and colourless gas bubbles form at the anode

A silvery grey solid forms on the cathode and a yellow-green gas forms at the anode