Temperature
Does a higher or lower temperature increase the speed of a chemical reaction?
Higher Temperature
Does a larger or smaller surface area increase the speed of a chemical reaction?
A larger surface area.
Does a higher or lower concentration increase the speed of a chemical reaction?
Higher.
What is a catalyst?
A substance that speeds up a chemical reaction without being used up.
What are the four main factors that control the rate of a chemical reaction?
Temperature, surface area, concentration and the presence of a catalyst.
Match each reaction time with the temperature:
Temperature:
A. 60°C
B. 40°C
C. 20°C
Times:
1. 37 seconds
2. 1:42
3. 10 seconds
A-3, B-1, C-2
Which would have a faster reaction: whole, halves, quarters, powder.
Powder
Why does increasing concentration increase the rate of a reaction?
There are more reactant particles in the same volume, increasing the frequency of collisions.
Does a catalyst increase or decrease the rate of a chemical reaction?
Increase.
What is a basic safety precaution needed when experimenting?
- Wear safety goggles
- Tie back long hair
- Wear enclosed leather shoes
- Jackets off
What happens to the average kinetic energy of particles when temperature increases?
It increases.
What happens to surface area when a solid is crushed into smaller pieces?
The surface area increases.
Match each hydrochloric acid concentration to its reaction time:
A. 0.1 M
B. 1 M
C. 2 M
Times:
1. 16 seconds
2. 2:45
3. 42 seconds
A–2, B–3, C–1
What does a catalyst do to the activation energy of a reaction?
It provides an alternative reaction pathway with a lower activation energy.
What products are formed when calcium carbonate and hydrochloric acid react with each other?
Calcium chloride, carbon dioxide and water.
Why did we place the hydrochloric acid in water baths at 20°C, 40°C and 60°C before adding the calcium carbonate?
To ensure the hydrochloric acid was at the intended temperature before the reaction began, allowing us to accurately investigate the effect of temperature on reaction rate.
In our surface-area investigation, the dishwashing tablet took 8:48 to dissolve when whole, 8:08 when cut in half, 6:30 when cut into quarters and 43 seconds when powdered. What trend does this data show about surface area?
As surface area increased, the dissolving time decreased. The powder had the greatest surface area and dissolved fastest, in 43 seconds.
What does concentration mean?
The amount of a substance dissolved in a certain volume of solution.
Secondary data showed the following average reaction times for yeast catalase: 0% H₂O₂ = 64.84 s, 0.1% = 36.45 s, 0.2% = 23.83 s, 1% = 9.33 s, 3% = 1.95 s and 5% = 1.02 s. What does this data show about the reaction when catalase is present?
The reaction became faster as the hydrogen peroxide concentration increased, showing that catalase can rapidly catalyse the decomposition of hydrogen peroxide.
What is activation energy?
The minimum energy required for a successful chemical reaction to occur.
Why does increasing temperature increase reaction rate?
Particles have greater average kinetic energy, causing more frequent and energetic collisions. A greater proportion of particles can overcome the activation energy, increasing the number of successful collisions.
How does increasing surface area increase the rate of reaction?
More particles become exposed to other reactants, creating more opportunities for collisions to occur at the same time.
Our results showed that 0.1 M hydrochloric acid took the longest time while 2 M took the shortest time to finish reacting. Why is this?
Because the 2 M hydrochloric acid solution had a higher concentration than the 1 M and 0.1 M
In our elephant toothpaste experiment, what role did the yeast play?
Yeast acted as a catalyst. Its catalase enzyme catalysed the decomposition of hydrogen peroxide, producing oxygen rapidly.
Using collision theory, explain how temperature, surface area, concentration and a catalyst can increase reaction rate.
Increasing temperature gives particles more kinetic energy; increasing surface area exposes more particles; increasing concentration increases the number of particles available for collisions; and a catalyst lowers activation energy. These changes increase the number of successful collisions and therefore increase reaction rate.