Q. For a reaction at equilibrium, if the concentration of products is increased, what will happen to the position of equilibrium according to Le Chatelier's principle?
A.
Shift to the right
B.
Shift to the left
C.
No change
D.
Depends on temperature
Solution
According to Le Chatelier's principle, increasing the concentration of products will shift the equilibrium position to the left to counteract the change.
Q. In a reaction where the rate constant doubles with a 10°C increase in temperature, what is the approximate activation energy (Ea) if R = 8.314 J/(mol·K)?
A.
40 kJ/mol
B.
80 kJ/mol
C.
120 kJ/mol
D.
160 kJ/mol
Solution
Using the Arrhenius equation and the temperature dependence of the rate constant, Ea can be estimated using the formula Ea = (R * ΔT * ln(2)) / (1/T1 - 1/T2). For a 10°C increase, Ea is approximately 80 kJ/mol.
Q. In a reaction where the rate is dependent on the concentration of two reactants, what is the term for the concentration of reactants at which the reaction rate is half of its maximum?
A.
Equilibrium concentration
B.
Half-life concentration
C.
Saturation concentration
D.
Threshold concentration
Solution
The saturation concentration is the concentration at which the reaction rate is half of its maximum value.
Q. In a reaction with a rate constant k, if the concentration of reactant A is doubled, how does the rate change if the reaction is second order with respect to A?
A.
Rate remains the same
B.
Rate doubles
C.
Rate quadruples
D.
Rate increases by a factor of eight
Solution
For a second order reaction, if [A] is doubled, the rate increases by a factor of (2^2) = 4, thus the rate quadruples.