Explanation:
The rate expression can only be determined experimentally.

Explanation:
Kc>1, and so lies towards the right with the yellow product at equilibrium; the color would therefore be a pale green due to more yellow than blue.
When an acid is added, it reacts with the OH− reducing its concentration. Equilibrium shifts to the right to oppose that change.

Kc only changes with temperature. Adding an alkali would increase the OH− concentration and therefore the equilibrium would shift to the left to oppose that change. Kc again would remain the same as it is only affected by temperature.

Explanation:
The y-intercept = $lnA$ so must be larger for reaction 1.
The gradient (slope) is equal to −Ea/R so, must be shallower (less negative) for reaction 1.
The question is in the “hard” category as students must know how to interpret an Arrhenius plot (or correctly interpret the given equation) and compare two reactions graphically.

Explanation:
The solid KI will dissolve until the solution is saturated and then a dynamic equilibrium will be established where the rate of precipitation is equal to the rate of dissolution of the excess solid.
The system must be closed and therefore no matter can be exchanged with the surroundings.

Explanation:
A catalyst provides an alternative pathway for the reaction lowering the activation energy. It affects both the forward and reverse reaction rates equally. The position of equilibrium will not change.

Explanation:
Using trials 1 and 2, as the concentration of I^− doubles, the rate also doubles. Rate and [I−] are therefore, directly proportional with an order of 1.

Explanation:
The rate constant, $k$, is the feature of the rate equation that is affected by temperature according to the Arrhenius equation k=Ae−Ea/RT.
The graph of rate vs temperature always shows this general trend, and similar questions have been asked several times in past papers.
The question is of moderate difficulty as the use of a specific example and reference to rate rather than k may derail some students. Confusion with the Arrhenius plot could also lead students to select option B.

Explanation:

The correct balanced equation is:

2LiOH + H2SO4 → Li2SO4 + 2H2O.

2+1+1+2 = 6

Explanation:

Kc is written as the concentrations of the products divided by the concentrations of the reactants each raised to the power of the coefficient in the balanced equation.

Explanation:
Students should be aware of the definition of frequency factor. However, questions on this topic are somewhat uncommon, and students could confuse this concept with the idea that molecules capable of successful collision lie above Ea in a Boltzmann distribution (leading them to select option D). The difficulty level is therefore at the higher end of the “easy” range.

Therefore, 0.5 moles of H2require 0.167 moles of N2 to completely react. There are $s$ of N2NX2 available so N2 is the reactant in excess.

Explanation:
OH− ions react with the H+ ions, thus decreasing their concentration. The equilibrium shifts towards the reactants to produce more H+ and resist this change (Le Chatelier’s principle). This produces more yellow chromate ions.
The value of Kc is only affected by temperature so this is unchanged.

Explanation:
Using the Arrhenius equation k = Ae−Ea/RT, a linear relationship will be created by graphing ln k vs. 1/T

Explanation:
Rate is directly proportional to the concentration of $M$ as it is first order. As the concentration of $M$ has been multiplied by 1.5, the rate (0.5 s−1) must also be multiplied by 1.5.

Explanation:
Q>Kc, therefore the backward reaction will be favored as the system approaches dynamic equilibrium.
The backward reaction is endothermic, so the temperature will decrease.
There are more moles of gas on the left and so pressure increases. NO2 is red-brown and so the gas mixture will get darker.

Explanation:
The endothermic reaction is favoured when the temperature increases. The concentration of products increases at t=10 mins; therefore, the forward reaction must be endothermic.
Increasing the volume decreases the pressure and causes the side with more moles of gas to be favoured. The concentration of reactants increases at t=15 mins; therefore, the reactants must have more moles of gas than the products.

Explanation:
$)$.
If $\Delta G$ is positive, ln(K) must be negative. ln(K) is negative for values smaller than 1.
A positive $\Delta G$ value indicates that the reaction is not spontaneous. Therefore, the equilibrium concentrations of the reactants are larger than the ones of the products; the equilibrium constant is less than 1.