Identifying Catalysts and Understanding Catalytic Action Quiz

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.

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.