Catalyst Quiz: Understanding Catalytic Action and Identifying Catalysts

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Questions and Answers

What is the role of catalysts in a reaction?

Provide an alternative pathway with a higher activation energy

Increase the rate of reaction by lowering the activation energy (correct)

Decrease the rate of reaction

Change the overall mass of the reactants

Why are catalysts not included in the reaction equation?

Because they remain unchanged throughout the reaction (correct)

Because they are consumed during the reaction

Because they have a higher activation energy

Because they increase the mass of the products

How do catalysts affect the activation energy of a reaction?

Double the activation energy

Lower the activation energy (correct)

Have no effect on activation energy

Increase the activation energy

Which statement is true about enzymes acting as catalysts in biological systems?

Enzymes speed up reactions in biological systems Signup and view all the answers

What happens to the rate of a reaction when a catalyst is present?

The rate increases Signup and view all the answers

Why do more particles have energy greater than the activation energy when a catalyst is present?

Because catalysts provide an alternative pathway with lower activation energy Signup and view all the answers

How does increasing the concentration of reacting solutions affect the rate of reaction?

Increases the rate by increasing collision frequency Signup and view all the answers

What effect does increasing the pressure of reacting gases have on the rate of reaction?

Increases the rate by enhancing collision frequency Signup and view all the answers

How does a greater surface area to volume ratio of a solid affect the rate of reaction?

Increases the rate by providing more surfaces for reactions to occur on Signup and view all the answers

What are catalysts?

Substances that speed up reactions without being consumed Signup and view all the answers

Which factor related to reacting solids affects the rate of reaction?

Surface area to volume ratio Signup and view all the answers

What happens to catalysts during a chemical reaction?

They remain unchanged and can be reused Signup and view all the answers

What can be used to measure the rate of reaction by recording the total volume of gas collected at regular intervals?

Burette Signup and view all the answers

What units may be used to express the rate of reaction?

m/s Signup and view all the answers

What does the gradient of a rate of reaction graph represent?

Rate of reaction Signup and view all the answers

How does increasing temperature affect the rate of reaction?

Increases the rate of reaction Signup and view all the answers

In terms of frequency and energy of collision between particles, what effect does an increase in pressure have on the rate of reaction?

Increases both frequency and energy of collisions Signup and view all the answers

What would be the most appropriate unit to measure the amount of product formed over time?

$mol/s$ Signup and view all the answers

How is the rate of reaction calculated when using the volume of gas produced as a measure?

$volume-of-gas/time$ Signup and view all the answers

Which factor does NOT typically increase the rate of reaction?

Decreased concentration Signup and view all the answers

'1/t is proportional to rate and gradients of graphs' implies what relationship between time and rate?

$t imes Rate = k$ Signup and view all the answers

What effect does increasing the surface area have on the rate of reaction?

$Increases$ Signup and view all the answers

Study Notes

Catalysts in Reactions

Catalysts are substances that increase the rate of a reaction without being consumed or altered in the process.
They are not included in the reaction equation because they are not reactants or products.
Catalysts lower the activation energy required for a reaction to occur, allowing more particles to react.

Enzymes as Catalysts

Enzymes are biological molecules that act as catalysts, increasing the rate of reactions in biological systems.
They are highly specific, meaning each enzyme only catalyzes one specific reaction.

Effect of Catalysts on Reaction Rate

When a catalyst is present, the rate of a reaction increases.
This is because more particles have energy greater than the activation energy, allowing them to react.

Factors Affecting Reaction Rate

Increasing the concentration of reacting solutions increases the rate of reaction.
Increasing the pressure of reacting gases increases the rate of reaction by increasing the frequency and energy of collisions between particles.
A greater surface area to volume ratio of a solid increases the rate of reaction by providing more sites for reaction to occur.

Measuring Reaction Rate

The rate of reaction can be measured by recording the total volume of gas collected at regular intervals using a gas syringe.
The rate of reaction can be expressed in units such as mol/L/s or cm³/s.
The gradient of a rate of reaction graph represents the rate of reaction.

Temperature and Reaction Rate

Increasing the temperature increases the rate of reaction by increasing the energy of particles and the frequency of collisions.

Calculating Reaction Rate

When using the volume of gas produced as a measure, the rate of reaction can be calculated by dividing the volume of gas produced by the time taken.

Factors Not Affecting Reaction Rate

Increasing the volume of the reaction vessel does not typically increase the rate of reaction.

Time and Rate Relationship

The relationship between time and rate is inverse, meaning that as time increases, the rate of reaction decreases.

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Description

This quiz covers the identification of catalysts in reactions, and explains how catalysts work by lowering activation energy and providing an alternative pathway for the reaction to occur. Catalysts remain unchanged throughout the reaction and are not included in the reaction equation.

Identifying Catalysts and Understanding Catalytic Action Quiz

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