Rates of reaction prequizz

Enzymes:

• only function at a temperature of 37°C and a pH of 1.5.

• are always flexible and can change their structure depending on the substrate.

• are proteins that catalyse chemical processes in plants and other organisms.

• are used up in biochemical reaction and the body constantly needs to produce more.

Increasing the temperature in a reaction does not change:

• the frequency of collisions.

• the activation energy.

• the kinetic energy of the moving reactants.

• the rate of the reaction.

Which one is not a property of a catalyst?

• It decreases the activation energy.

• It enables reactions to take place at a lower temperature.

• It increases the overall total yield in a reaction.

• It has the same chemical structure before and after a catalytic reaction.

Identify the reaction with a homogeneous catalyst.

• 2 SO₂(g) + O₂(g) → 2 SO₃(g) catalyst: NO(g)

• 2 H₂(g) + O₂(g) → 2 H₂O(l) catalyst: Pt(s)

• 2 H₂O₂ (l) → 2 H₂O(g) + O₂(g) catalyst: MnO₂(s)

• 2 SO₂(g) + O₂(g) → 2 SO₃(g) catalyst: V₂O₅(s)

How many transition states does the catalysed and uncatalyzed reaction have?

• TS (catalysed) = 1 and TS (uncatalysed) = 0

• TS (catalysed) = 1 and TS (uncatalysed) = 1

• TS (catalysed) = 2 and TS (uncatalysed) = 1

• TS (catalysed) = 2 and TS (uncatalysed) = 2

How do the purple and green curve differ if both are for the same particles?

• The purple curve is without catalyst.

• The purple curve has a higher average kinetic energy.

• The purple curve has a lower activation energy.

• The purple curve is at a lower temperature.

In a balloon, the kinetic energies of the particles at SLC (standard laboratory conditions) are:

• all the same and can be derived from the temperature.

• distributed over a range of energies.

• all the same and can be derived from the molecular mass of the gas.

• zero as they are in a closed system.

The kinetic energy is lowest for molecules or atoms:

• in the liquid state.

• in the solid state.

• in the gaseous state.

• in the aqueous state.

Identify how the rate of a gas reaction in a closed system could be decreased.

• Adding a catalyst

• Increasing the temperature

• Increasing the volume

• Increasing the pressure

The activation energy is:

• the energy difference between reactants and products.

• the minimum energy of colliding particles.

• the minimum energy required for a reaction to occur.

• equal to the kinetic energy of particles.