The Rate and Extent of Chemical Change Flashcards
What is the rate of reaction?
The rate of reaction is how quickly the reactants are used up or the products are formed during a chemical reaction
Name four factors that affect the rate of reaction.
Temperature, concentration (or pressure), surface area, and the presence of a catalyst.
How does temperature affect the rate of reaction?
Increasing the temperature increases the rate of reaction because the particles move faster, collide more frequently, and with greater energy, leading to more successful collisions.
How does concentration (or pressure) affect the rate of reaction?
Increasing the concentration of a solution or the pressure of gases increases the rate of reaction because there are more particles in a given volume, leading to more frequent collisions.
How does surface area affect the rate of reaction?
Increasing the surface area of a solid increases the rate of reaction because more particles are exposed to react with other substances, leading to more collisions.
How does a catalyst affect the rate of reaction?
A catalyst increases the rate of reaction by lowering the activation energy, providing an alternative pathway for the reaction.
How can you measure the rate of reaction when a gas is produced?
By measuring the volume of gas produced over time using a gas syringe or by collecting the gas in an upturned measuring cylinder.
How can you measure the rate of reaction when a precipitate forms?
By observing the disappearance of a mark or measuring how long it takes for a precipitate to form and block light using a colorimeter.
How can you measure the rate of reaction by monitoring the change in mass?
By measuring the loss of mass using a balance, as a gas is released during the reaction.
What is the collision theory?
The collision theory states that for a reaction to occur, particles must collide with sufficient energy (called activation energy) and proper orientation.
How do effective collisions affect the rate of reaction?
Only collisions with sufficient energy and proper orientation lead to a successful reaction. Increasing the frequency of effective collisions increases the rate of reaction.
How does activation energy relate to the rate of reaction?
Higher activation energy means fewer particles have enough energy to react, leading to a slower reaction. Lower activation energy speeds up the reaction.
What is a reversible reaction?
A reaction in which the products can react to form the original reactants, meaning the reaction can go in both directions.
What is dynamic equilibrium?
It occurs in a closed system when the rate of the forward reaction equals the rate of the reverse reaction, so the concentrations of reactants and products remain constant.
How does changing the concentration affect equilibrium?
According to Le Chatelier’s Principle, increasing the concentration of a reactant or product will shift the equilibrium to counteract the change, either by producing more products or reactants.
How does temperature affect equilibrium?
Increasing temperature shifts the equilibrium towards the endothermic direction (absorbs heat), while decreasing temperature shifts the equilibrium towards the exothermic direction (releases heat).
How does pressure affect equilibrium in reactions involving gases?
Increasing pressure shifts the equilibrium to the side with fewer gas molecules; decreasing pressure shifts the equilibrium to the side with more gas molecules.
How is the rate of reaction calculated from concentration?
The rate can be determined by measuring the change in concentration over time. Rate = change in concentration / time.
How can you determine the rate from a graph?
The rate of reaction is the slope of the concentration vs. time graph. A steeper slope indicates a faster rate of reaction.
What is the role of a catalyst in a chemical reaction?
A catalyst speeds up the rate of a reaction by providing an alternative pathway with a lower activation energy, but it is not used up in the reaction.
How does the presence of a catalyst affect the activation energy?
The catalyst lowers the activation energy, making it easier for reactants to form products.
Give an example of a biological catalyst.
Enzymes are biological catalysts that speed up biochemical reactions in living organisms.
How does a higher concentration of reactants affect the reaction rate?
It increases the rate of reaction because there are more particles in the same volume, leading to more frequent collisions.
How does increasing temperature affect the reaction rate?
It increases the rate of reaction because particles move faster, collide more frequently, and with more energy, leading to more successful collisions.
What is the effect of reducing particle size (increasing surface area) on the rate of reaction?
Reducing the particle size increases the surface area, leading to more collisions between particles and increasing the rate of reaction.
What is an example of a reaction with a fast rate of reaction?
Combustion of fuels (e.g., burning a matchstick).
What is an example of a reaction with a slow rate of reaction?
The rusting of iron or the weathering of rocks.
Why is the rate of reaction important in industrial processes?
Increasing the rate of reaction can increase efficiency and reduce costs in processes like the manufacture of chemicals and pharmaceuticals.
How can you increase the rate of reaction in an industrial process?
By increasing temperature, pressure (for gases), or concentration, and using catalysts to speed up reactions without consuming them.
Why is it important to control the rate of reaction in some chemical processes?
In some reactions, controlling the rate ensures safety, efficiency, and quality control of the products, e.g., in pharmaceuticals, food processing, and explosives.
