Topic 8 - Rates of Reaction and Energy Change (Year 11) Flashcards
What are the three ways of collecting rate of reaction data?
Measuring decreasing mass, Measuring volume of gas given off and measuring light passing through a solution.
When measuring the rate of reaction using a balance, how do you know the reaction has finished?
The mass will stay constant
When measuring the rate of reaction using a gas syringe, how do you know the reaction has finished?
The volume of gas will stay constant.
A measuring cylindar can be used to measure the rates of reaction in an experiment. What piece of equipment can also be used to measure the gas from an experimennt?
Gas syringe
What is the equation used to to calculate the rate of reaction?
Mean rate of reaction = volume of reactant used/product formed ➗ time taken
An experiment is being carried out into the rate of reaction of an experiment using a mass balance. The reaction gives off a harmful gas. Apart from wearing gloves, lab coat and safety glasses what other safety precautions could be taken?
Carry out the the experiment in a fume hood.
Sodium thiosulfate and hydrochloric acid solutions are both clear, colourless solutions. When added together, they react to form a yellow precipitate. Breifly outline a method that you could use to investigate this rate of reaction.
Draw a cross ona piece of paper and place under a conical flask. Add the reactants into the conical flask and start the stopwatch. Record the time taken for the cross to dissapear by the precipitate.
When sodium carbonate is added to hydrochloric acid, a gas is released. Breigly outine a method you could use to investigate this rate of reaction.
Add the acid into a concial flask that is attached to a gas syringe. Add the marble chips. Collect the gas given off and measure the volume at given time points.
What are the five different ways of speeding up the rate of reaction?
Temperature, Concentration, Surface area, Pressure, Catalyst
How will increasing temperature affect rate of reaction? Explain why.
Particals have more energy, they move faster and therefore have more chance of colliding. When they do collide they collide with more energy, meaning ha higher chance of a reactin. This will increase the rate of reaction.
How will increasing pressure affect rate of reaction of gases? Explain why.
Increasing pressure, means the same number of particles in a smaller volume. This means particles are more likely to collide, more likely to react and increase the rate of reaction.
How will increasing sureface area affect rate of reaction? Explain why.
Increasing surface area increases the area in which particles can collide. This means particles are more likely to collide, more likely to react and increase the rate of reaction.
How will increasing concentration affect rate of reaction? Explain why.
Increasing particles, increases the number of particles in a given volume. This means particles are more likely to collide, more likely to react and increase the rate of reaction.
How will decreasing temperature affect rate of reaction? Explain why.
Decreasing temperature, particles have less energy. This means that they move slower, meaning fewer chances of collisions, when they do collide they have less energy and less likely to react.
How will decreasing pressure affect rate of reaction? Explain why.
Decreasing pressure, same number of particles in more space. This means particles are less likely to collide and decreases the rate of reaction.
How will decreasing sureface area affect rate of reaction? Explain why.
Decreasing surface area, less area for the particles to collide with the reactant. This means particles are less likely to collide and decreases the rate of reaction.
How will idecreasing concentration affect rate of reaction? Explain why.
Decreasing concentration, same number of particles in more volume.This means particles are less likely to collide and decreases the rate of reaction.
Explain how a catallyst works.
Increases the rate of reaction, by decreasing the activation energy. A catalyst doesn’t get used up in a reaction.
How could you increase the surface area of a 5g marble chip?
By breaking the marble chip up into smaller pieces.
When the line on a rate of reaction graph goes flat, what does this tell you about the reation at that point?
When the line goes flat it means that the reaction has finished - no more gas is being produced.
What product of the sodium thiosulfate and hydrochloric acid reaction cause the solution to go colourless?
Solid sulfur is produced in a precipitation reaction, causing the solutin to turn a yellow colour
What is always the dependednt variable in a rate of reaction experiment?
Time taken
What is the equation of a staight line?
gradient = change in Y ➗ change in X
Two lines, X and Y, are draw on the same graph showing volume of gas produced against time. Line Xhas a steepergradient than line Y. What does this tell you?
X has a faster rate of reaction than line Y. The steeper the gradient the faster the rate of reaction.
If you wanted to calculate the rate of a reaction at a specific point what would you do?
Draw a tangent at the specific time, then calculate the gradient.
How does a catalyst affect rate of reaction?
It speeds up the rate of reaction without being used up.
What will happen to the rate of reaction if the concentration of the reactants are increased?
The rate of reaction will increase.
What is the function of an enzyme?
An enzyme is a biological catalyst. I5t speeds up the rate of reaction in a living cell.
Name a biological catalyst
Yeast
What must happen in order for a reaction to take place?
Particals must collide
Define Collision theory
For a reaction to take place, particles must collide, when they collide they have to collide with enough energy (activation energy) and in the correct orientation.
Explain what is meant by activation energy
Minimum amount of energy needed for a reaction to take place
What is the definition of an exothermic reaction?
A reaction that releases energy/heats up. Ex - Exits
What is the definition of an endothermic reaction?
A reaction that takes in energy/cools down. En - enters.
How do we show the energy changes in a reaction?
Energy Profile
Do exothermic reactions have a positive or negative energy change?
negative
Do endothermic reactions have a positive or negative energy change?
positive
Is bond-breaking an exothermic or endothermic process?
endothermic
Is bond-forming an exothermic or endothermic process?
exothermic
What distance on a reaction profile represents the the activation energy of the reaction?
Distance between the reactants and the top of the nergy profile curve.
What distance on a reaction profile represents the the energy change of the reaction?
The distancer between the reactants and products.
In an experiment how would you test to see whether is is an exothermic or endothermic reaction?
Use a thermometer - if it there is an increase it is exothermic, if a deacrease it is endothermic.
True or false: A temperature change always occurs during a precipitation reaction?
True - precipitation reactions are exothermic reactions so will give heat to the surroundings.
True or False: Combustion is an example of a endothermic reaction?
False - combustions gives out heat so is therefore exothermic.
True or False: Thermal Decomposition is an example of a endothermic reaction?
True - the process of thermal decomposition involves a carbonate being heated (gaining heat from the surroundings) to break own into different products.
Give two ways of insulating a reaction mixture when measuring a temperature change
Carry out the process in a polystyrene cup, add cotton wool to the outside of the reaction vessel, put a lid on the reaction vessel.
True or False: In an exothermic reaction the products have more energy than the reactants?
False - the products have less energy and energy is released to the surroundings.
True or False: In an endothermic reaction the products have more energy than the reactants?
True - energy from the surroundings is turn into chemical energy stored in the products.
Ammonim chloridedissolving in water is an endothermic process. How would the temperature of the water change during this reaction?
The temperature would decrease.
Breifly describe how you could carry out an experiment to measure the temperature change when a salt is dissolved in water.
Place water into a polystyrene cup. Measure the initial temperature, the add the salt to the water. Weasure the temperature when all the salt has dissolved. Work out the difference in the initial temperature and the final temperature.
How do you calculate the total energy change of a reaction?
Total energy change = total bond energy of reactant - total bond energy of products
Define: Rate of Reactrion
A measurement of how fast the reaction happens.
Define: Catalyst
A catalyst speeds up the rate of a reaction without being used up in the reaction.
