1022SCG - QB3 - T2 2024

Which of the following statements is least accurate?

• Reactant molecule collisions don’t always create product molecules

• Higher temperatures mean that molecules move with larger average speeds

• The free energy drop from reactant to product determines the reaction rate

• Exothermic reactions proceed more quickly at higher temperatures.  

Which of the following statements are incorrect regarding Le Chatelier’s principle?

• If a closed system in equilibrium has its pressure increased, the reaction will shift in favour of the side with the most molecules.

• If a system in equilibrium has part of its products removed, the reaction will shift towards the products.

• If the temperature is increased during an endothermic reaction in equilibrium, the reaction will go on to produce more reactants

• None of the above

What is the order of the following elementary reaction?

                2HI → H₂ + I₂  

• 1^st Order

• 2^nd Order

• 3^rd Order

• Must be determined experimantally

The rate-determining step of a chemical reaction can be best described as:

• The final step or elementary reaction

• The step impacted by the addition of the catalyst

• The first step or elementary reaction

• The slowest step or elementary reaction

Water vapor and carbon monoxide react to form carbon dioxide and hydrogen gas in the water gas shift reaction: CO (g) + H₂O (g) ⇌ CO₂ (g) + H₂ (g), which is exothermic. Which of the following interventions will shift the reaction towards forming more products?

• Increasing the temperature

• Adding more carbon monoxide (CO)

• Increasing the pressure

• Adding a catalyst

Which of the following is false about a catalyst?

• A catalyst changes the rate of reaction while undergoing a permanent change

• The action caused by a catalyst is called catalysis

• A heterogenous catalyst exists in a separate phase to the reactants

• A homogenous catalyst exists in the same phase as the reactants

Calculate the initial rate for the production of C in the reaction A + B -> C if the rate law for the reaction is Rate = k[A]²[B]¹.

The initial concentrations for the reactants are 0.03M for A and 0.05M for B and k =  3x10^-5 M^-2s^-1

• 1.4 x10^-9 M s^-1

• 3.5 x10^-3 M s^-1

• 1.8 x10^-4 M s^-1

• 4.8 x10^-5 M s^-1

Choose the best option: a rate law can include the concentration of a _______.

• Solid product

• Solvent

• Homogeneous catalyst

• Heterogeneous catalyst

When a reversible reaction reaches equilibrium, the best explanation is that

• The temperature has become too low for colliding molecules to react.

• The forward and reverse reactions are now occurring at equal rates.

• There are now equal amounts of products and reactants.

• Reactant molecules no longer collide frequently enough for reactions to occur.

The following data is from the reaction 2R + S → T + U. What is the rate law for this?

• Rate = k ( [R]² + [S] )

• Rate = k [2R] [S]

• Rate = k [R]² [S]²

• Rate = k [R]² [S]