Key Vocabulary
What do we call a chemical reaction that happens quickly?
A fast reaction
Increasing temperature usually makes reactions go faster or slower?
Faster
For a reaction to occur, particles must do what?
Collide
In the sodium thiosulfate "disappearing cross" experiment, what is measured?
The time taken for the cross to disappear
On a rate of reaction graph, what does a steeper line indicate?
A faster reaction
What is the name given to anything that increases the rate of a reaction without being used up?
A catalyst
Crushing marble chips into powder increases which factor?
Surface area
Do all collisions result in a reaction?
No
In a magnesium and hydrochloric acid experiment, what gas is produced?
Hydrogen
What does a flat line at the end of a reaction graph show?
The reaction has stopped
What do scientists mean by the rate of reaction?
How fast reactants are turned into products
What happens to the rate of reaction when concentration is increased?
It increases
What two conditions are needed for a successful collision?
Enough energy and correct orientation
What is the independent variable?
The variable you change
If Reaction A reaches the finish point before Reaction B, which has the greater rate?
Reaction A
The reactants need this minimum amount of energy before they can react.
Activation energy
Why does increasing pressure increase the rate of reactions involving gases?
Gas particles are closer together, so collisions happen more often
Why does a higher temperature increase the rate of reaction according to collision theory?
Particles move faster and more collisions have enough energy
What is the dependent variable?
The variable you measure
Rate can be calculated using the formula:
Rate = Amount of product formed ÷ Time taken
What theory explains reactions in terms of particles colliding?
Collision theory
Name the four main factors that affect the rate of reaction.
Temperature, concentration, surface area, and catalysts
How does a catalyst increase the rate of reaction?
It provides an alternative pathway with lower activation energy
Why should control variables be kept the same?
To make the test fair
A reaction produces 100 cm³ of gas in 20 seconds. What is the average rate?
5 cm³/s