C6 Rates of Reactions

Flashcards covering collision theory, factors affecting rates of reaction, graph interpretations, and rate calculations from the C6 Rates of Reactions notes.

How can you measure the quantity of a reactant or product?

In grams or in $cm^3$.

What are the two possible units for the rate of reaction?

$g/s$ or $cm^3/s$ (where $s$ is seconds).

What factors can affect the rate of a reaction?

Temperature, surface area of a solid, concentration or reactants in solution, and pressure of gases.

What is a catalyst?

Something which changes the rate of a reaction but is not used up in that reaction.

What is a reversible reaction?

A reaction which can go from reactants to products but also from products to reactants.

What is the definition of activation energy?

The amount of energy a particle needs before it will be able to react when it collides with another particle (the minimum amount of energy needed for a collision to be successful).

What two conditions are required for a chemical reaction to happen according to collision theory?

Reactant particles must collide with each other, and the particles must have enough energy for them to react.

What is a successful collision?

A collision that produces a reaction.

How does collision frequency affect the rate of reaction?

The greater the frequency of successful collisions, the greater the rate of reaction.

Which factors increase the rate of reaction?

Increasing the temperature, increasing the pressure of gases, increasing the concentration of solutions, increasing the surface area of solids, and using a catalyst.

On a graph of mass or volume of product formed against time, what does the steepness of the line indicate?

The steeper the line, the greater the rate of reaction.

What happens to the slope of a rate graph when a reaction has completed?

When a reaction has completed, the slope levels off.

How does the leveling off of faster reactions compare to slow reactions on a rate graph?

Faster reactions level off sooner than slow reactions.

What are the two equations used to calculate the mean rate of reaction?

$\text{mean rate of reaction} = \frac{\text{quantity of reactant used}}{\text{time taken}}$ or $\text{mean rate of reaction} = \frac{\text{quantity of product formed}}{\text{time taken}}$

How do you calculate the rate of reaction for a reaction which produced $50\,cm^3$ of gas in $10\text{ seconds}$?

$$\text{Rate} = \text{volume} \div \text{time} = 50 \div 10 = 5\,cm^3/s$$