Chemical Reactions Quiz

What is required according to the collision theory for a reaction to occur?

• Proper orientation and sufficient energy

• High temperature and pressure

• Presence of a catalyst

• Low activation energy

Which factor is likely to increase the rate of a chemical reaction?

• Decrease in reactant concentration

• Increase in temperature

• Use of a larger container

• Removal of a catalyst

Which scenario will result in a faster reaction rate?

• Zinc in HCl at 298 K

• Zinc in HCl at 320 K

• 5 g of thick platinum wire

• O₂ + H₂ at a pressure of 1.00 atm

True or False: A catalyst causes a reaction to speed up and the enthalpy change to increase.

• True

• False

What is the definition of Chemical Equilibrium?

• The state where reactants are converted to products at the same rate as products revert to reactants

• The state where no reactants remain

• The state where all chemical reactions stop

• The state where temperature remains constant

What does Le Chatelier's principle state?

• If a dynamic equilibrium is disturbed by changing the conditions, the position of equilibrium moves to counteract the change

• Increasing temperature always increases the reaction rate

• Pressure has no effect on the equilibrium of a reaction

• All reactions are reversible

According to Le Chatelier's principle, what would be the effect on the equilibrium position if the concentration of NO (g) is increased in the reaction 2 NO (g) + O2 (g) ⇌ 2 NO2 (g)?

• Shifts to the right

• Shifts to the left

• No shift

• Shifts upwards

What happens to the equilibrium position when the temperature is increased for the exothermic reaction 2 NO (g) + O2 (g) ⇌ 2 NO2 (g) + 185 kJ?

• Shifts to the right

• Shifts to the left

• No shift

• Shifts downwards

When the temperature is increased in the reaction 2H⁺ (aq) + 2CrO₄²⁻ (yellow) (aq) ⇌ Cr₂O₇²⁻ (aq) (orange) + H₂O (l), the solution turns orange. Is this reaction endothermic or exothermic in the forward direction?

• Endothermic

• Exothermic

• Neither

• Both endothermic and exothermic

A reaction that can occur in both the forward and the reverse directions is called what?

• reversible reaction

• law of chemical equilibrium

• equilibrium constant

• homogeneous equilibrium