PASS CHM1051 - Week 11-12

Increasing which of the following would decrease the rate of a reaction?

• Temperature

• Reactant

• Surface area

• Energy of activation

A radioactive substance has the half-time of 2 minutes. If there is initially 0.16 M of that substance in a jar, how much of it is left after 8 minutes?

• 0.01 M

• 0.02 M

• 0.04 M

• 0.08 M

A reaction uses up reactants A and B. When I double the concentration of A, the reaction will be ... if the reaction is first order with respect to A.

• the same

• doubles

• quadruples

• octuples

If a rate-limiting step is the first step in a reaction mechanism, then usually the whole reaction law is the reaction law of that particular step.

• True

• False

Which of the following would alter the reaction rate?

• surface area

• molecular orientation

• reactant concentration

• availability of catalysts

Which of the following is true about catalysts?

• Catalysts do not create alternate pathways

• Catalysts increase the reaction rate by increasing the energy of activation

• Catalysts alter the equilibrium to shift to the product side

• Catalysts are not consumed in the reaction

Which of the following is true about enzyme?

• All enzyme can operate without the presence of any "assistant" molecules

• Enzymes alter the equilibrium towards the products

• Enzymes are homogeneous catalysts

• Enzymes decreases the activation energy

What is the Michaelis-Menten constant?

• The substrate concentration when the enzyme hits Vmax

• The substrate concentration when the reaction rate is half the Vmax

• The substrate concentration when the Vmax is zero

• The number of enzyme needed to complete a reaction

What is the molecularity of an elementary step which is a second-order reaction?

• monomolecular

• bimolecular

• trimolecular

• quadromolecular

The slowest step in a reaction mechanism is always the rate-limiting step.

• True

• False