Chemical Kinetics - SS2 Chemistry Past Questions and Answers - page 2
What is the rate of Chemical reaction and how can it be measured?
The rate of a chemical reaction refers to how quickly or slowly a chemical reaction takes place. The rate of a chemical reaction refers to the speed at which reactants are converted into products. It is an important concept in chemistry as it allows us to understand and regulate the kinetics of chemical processes. The rate of a chemical reaction depends on multiple variables and plays a significant role in industries, environmental processes, and biological systems. It can be measured using various experimental methods which include:
1. Change in Concentration: Monitoring the change in reactant or product concentration over time using spectrophotometry, chromatography, or titration
2. Pressure Change (for Gaseous Reactions): Monitoring the pressure change in a closed system due to the production or consumption of gases.
3. Change in Mass: Measuring the change in mass due to the evolution of gas or the consumption of reactants.
4. Conductivity Change: Monitoring the change in electrical conductivity of a solution as reactants are converted into ions.
Users' Answers & CommentsWhich of the following factors can affect the rate of a chemical reaction?
Temperature
Concentration of reactants
Surface area
All of the above
The rate of a chemical reaction generally increases when:
Temperature decreases
Concentration of reactants decreases
Surface area decreases
None of the above
Which of the following statements is true about catalysts?
Catalysts are consumed during a reaction.
Catalysts lower the activation energy of a reaction.
Catalysts increase the rate of a reaction.
All of the above.
The rate of a chemical reaction can be determined by:
Measuring the change in concentration of reactants over time.
Observing the colour change of the reaction mixture.
Measuring the production of gas or heat during the reaction.
All of the above.
The collision theory of chemical reactions states that:
Reactions can only occur when reactant particles collide with sufficient energy.
All collisions between reactant particles result in a chemical reaction.
Temperature has no effect on the rate of a reaction.
The rate of a reaction is directly proportional to the concentration of reactants.
The Arrhenius equation relates the rate constant (k) of a reaction to:
Temperature and activation energy.
Concentration of reactants.
Surface area of the reactants.
Pressure of the reactants.
Which of the following statements is true about exothermic reactions?
Exothermic reactions release heat to the surroundings.
Exothermic reactions have higher activation energy than endothermic reactions.
Exothermic reactions always occur at a fast rate.
Exothermic reactions always produce gases.
In a reaction that follows first-order kinetics, the rate of the reaction is:
Directly proportional to the concentration of the reactants.
Inversely proportional to the concentration of the reactants.
Independent of the concentration of the reactants.
Proportional to the square of the concentration of the reactants.
Which of the following is NOT a method to increase the rate of a chemical reaction?
Increasing the temperature.
Adding a catalyst.
Decreasing the concentration of reactants.
Increasing the surface area of the reactants.