Rates of Reactions Questions P2

Question

Answer

What is the rate of a chemical reaction?

The speed at which reactants are converted into products.

How can the rate of a reaction be calculated?

By measuring the amount of reactant used or product formed over time.

What are the common units for rate of reaction?

grams per second (g/s), cubic centimeters per second (cm³/s), or moles per second (mol/s).

What is the formula for mean rate of reaction?

Mean rate = quantity of reactant used or product formed ÷ time taken.

What is collision theory?

A theory stating that chemical reactions occur when particles collide with sufficient energy.

What is activation energy?

The minimum amount of energy required for a reaction to occur.

How does increasing temperature affect the rate of reaction?

It increases particle energy, leading to more frequent and successful collisions.

How does increasing concentration affect the rate of reaction?

It increases the number of particles in a given volume, leading to more collisions.

How does increasing pressure affect the rate of reaction (for gases)?

It compresses gas particles, increasing collision frequency.

How does increasing surface area affect the rate of reaction?

Smaller particle sizes expose more surface area, leading to more collisions.

What is a catalyst?

A substance that increases the rate of a reaction without being consumed.

How do catalysts work?

They provide an alternative reaction pathway with a lower activation energy.

What is a reversible reaction?

A reaction where products can reform into reactants under certain conditions.

How is a reversible reaction represented?

With a double arrow: A + B ⇌ C + D.

What is dynamic equilibrium?

A state in a closed system where the forward and reverse reactions occur at the same rate.

What is Le Chatelier's Principle?

If a system at equilibrium is disturbed, it will adjust to counteract the change.

How does increasing temperature affect equilibrium in an exothermic reaction?

It shifts the equilibrium to favor the endothermic (reverse) reaction.

How does increasing pressure affect equilibrium in a gaseous reaction?

It shifts the equilibrium toward the side with fewer gas molecules.

What is the required practical for investigating the effect of concentration on reaction rate?

Measure how changing the concentration of a reactant affects the rate of reaction by observing gas production or color change.

In the practical measuring gas production, what is the independent variable?

The concentration of the reactant solution.

In the practical measuring gas production, what is the dependent variable?

The volume of gas produced over time.

In the practical observing color change, what is the method used?

Measure the time taken for a cross beneath a reaction mixture to disappear as the solution becomes cloudy.

What factors must be controlled in the required practicals?

Temperature, volume of reactants, and surface area of solid reactants.

How can the rate of reaction be determined from a graph?

By calculating the gradient (slope) of the line representing the reaction progress.

What does a steeper gradient on a rate of reaction graph indicate?

A faster rate of reaction.

What does a horizontal line on a rate of reaction graph indicate?

The reaction has completed; no further change in reactant or product quantity.