The Rate and Extent of Chemical Change

Created by

Nazmine

Cards (35)

What is the formula for calculating the mean rate of reaction?
mean rate of reaction = amount of reactant used or product formed / time taken
How can the rate of reaction be measured?
By measuring reactants used or products formed
What should you measure if a product is a gas?
Measure the mass before and after the reaction
What happens to the mass of the reaction mixture when a gas is produced?
The mass of the mixture will decrease
What are the units for the rate of reaction when measuring mass?
g/s
How is the concentration of a reactant calculated?
Concentration = amount (mol) / volume (dm³)
What is the unit for concentration?
mol/dm³
How can you measure the volume of gas produced in a reaction?
Using a gas syringe
What is the unit for the rate of reaction when measuring gas volume?
cm³/s
How do you measure the time for a solution to change color?
Time how long it takes to change color
What are the four factors that affect the rate of reaction?
Temperature
Concentration
Surface area
Catalysts
What happens to the rate of reaction at higher concentrations?
The rate of reaction increases due to more collisions
How does temperature affect the rate of reaction?
Higher temperature increases particle movement and collisions
How does increasing pressure affect the rate of reaction for gases?
It increases the frequency of collisions
What is the method to investigate how concentration affects reaction rates?
Set up equipment
Add hydrochloric acid and swirl
Start timer
Watch the cross through the flask
Stop timer when cross disappears
Repeat with different acid concentrations
What is the independent variable in the concentration reaction experiment?
The concentration of the acid
What is the dependent variable in the concentration reaction experiment?
The time for the cross to disappear
What are the control variables in the concentration reaction experiment?
Volume of acid and sodium thiosulfate
What is the relationship between acid concentration and reaction time?
Higher concentration leads to shorter reaction time
What safety precautions should be taken during the experiment?
Use eye protection due to corrosive acid
Why do smaller pieces of solid reactants increase reaction rates?
They have a larger surface area for collisions
What are the key points to remember when plotting reaction rates on graphs?
Steeper line indicates faster reaction
Line becomes horizontal when reactants are used up
Same amount of product from same reactants
How is the rate of reaction determined from a graph?
By finding the gradient of the tangent
What is a catalyst?
A substance that increases reaction rate without being used up
How do catalysts affect successful collisions?
They reduce energy needed for successful collisions
What role do enzymes play in biological systems?
Enzymes act as catalysts
Why is increasing reaction rates important in industry?
It helps to reduce costs
What are reversible reactions?
Reactions that can go forwards or backwards
Products can react to form original reactants
Represented as A(g) + B(g) ⇌ C(g) + D(g)
What happens in an exothermic reaction in reverse?
It becomes endothermic
What is achieved in a closed system during a reversible reaction?
An equilibrium is established
What does Le Chatelier's Principle state?
System shifts to resist changes in conditions
In exothermic reactions, higher temperature decreases yield
In endothermic reactions, higher temperature increases yield
How does pressure affect reactions involving gases?
Higher pressure favors reactions with fewer gas molecules
What happens if the concentration of a reactant is increased?
The equilibrium shifts to form more products
What occurs if the concentration of a reactant is decreased?
The equilibrium shifts to form more reactants
What factors determine optimum conditions in industrial processes?
Reaction rates
Concentration changes
Temperature adjustments
Pressure variations