Collision Theory
What must particles do for a chemical reaction to occur?
They must collide with each other
What does reaction rate describe?
How quickly a chemical reaction occurs
What is formed during a chemical reaction?
A new substance
What is the independent variable?
The variable that changes
What section of a lab report explains what we are investigating?
The aim
What happens to the reaction rate when successful collisions increase?
The reaction rate increases
Name one factor that can affect the rate of a chemical reaction:
Any one of the following:
Temperature, catalysts/enzymes, energy, particle size, concentration
Which of the following is considered a chemical change?
Ice melting, iron rusting or paper being torn
Iron rusting
What is the dependent variable?
The variable that is being measured/observed
In relation to risk assessment, what is meant by a mitigation strategy?
A planned action that reduces the likelihood of the identified risk.
What is the name of the type of chemical that speeds up the rate of chemical reactions?
Catalyst
A reaction takes 120 seconds in one condition and 40 seconds in another condition. What does this tell us about the reaction rate?
The reaction rate was faster under the condition that took 40 seconds
What does concentration tell us?
It tells us how much of a substance is present in a given volume of solution
Why do scientists keep some variables the same during an experiment?
To make it a fair test.
Ensures that changes in the dependent variable are due to the independent variable.
In your hypothesis, you should refer to what?
The independent and dependent variables
What does the collision theory explain?
Explains why different reactions occur at different rates.
What is a type of chemical reaction that occurs quickly and releases heat, light and sound?
Explosion
Which of the following is more concentrated:
5g of salt + 100ml water OR
20g of salt + 100ml water
20g of salt + 100ml water
A student repeats an experiment three times and gets similar results. What does this suggest?
The results are likely to be reliable
Reword the follow method step using the correct language:
I had to add 50ml of hydrochloric acid to a beaker and then start the stopwatch.
50ml of hydrochloric acid was added to a beaker and the stopwatch was started.
Crushing a solid reactant into a fine powder speeds up a reaction because it significantly increases what?
Surface area
Why does increasing the temperature generally make a reaction faster?
Particles have more energy and move faster, resulting in more frequent collisions
Name two pieces of evidence that shows a chemical reaction has occurred.
Any two of the following:
Gas produced, colour change, temperature change, precipitate formed, light produced, new smell
A student changes temperature and concentration at the same time. Why would it be difficult to determine which factor affected the reaction rate?
Because they changed two variables at once. They wouldn't know whether the change in reaction rate was caused by temperature, concentration or both.
What is the difference between a result and a conclusion?
Results are what you observed/measured.
Conclusion is what the results mean and whether they support the hypothesis.