Rates of Reaction

Question 1

Name 3 things that effect the rate of reaction?

Answer 1

temperature, concentration(pressure if it is gas) and size of particles

Question 2

What is the formula for Rate of reaction

Answer 2

Amount of reactant used or the amount of product formed divided by time

Question 3

Basic steps to a precipitation experiment are?

Answer 3

1. Mix the 2 reactant solutions and put the flask on a piece of paper that has a mark on it. 2. Observe the mark through the mixture and measure how long it takes for the mark to be obscured

Question 4

In an precipitation experiment disappears quickly, what does this tell us

Answer 4

Fast rate of reaction

Question 5

What are the disadvantages of the a Participation experiment

Answer 5

The results are subjective. On person might see the mark disappear quicker than another

Question 6

You can measure the rate of reaction that produces a gas using a mass balance. Explain

Answer 6

As gas is released the lost mass is easily measured on the balance. The quicker the reading on the balance drops, the faster the reaction.

Question 7

You can also measure the volume of gas given off. Explain

Answer 7

Set up the flask with a plug and syringe, add the mixture of reactants to the flask. Set a time interval for the gas to be collected. The more gas in the set time interval, the faster the reaction

Question 8

Precautions to take when collect gas in a reaction experiments

Answer 8

1. In mass balance experiment the gas is given off into the room, so for harmful gases then us a fume cupboard. When collecting a volume of gas, make sure you use the right syringe size as vigorous reactions may blow the plug out

Question 9

How does surface area affect rate of reaction

Answer 9

Larger surface area will increase the rate of reaction

Question 10

How can you measure the surface area affecting rate of reaction

Answer 10

You can put various forms of Calcium carbonate in Hydrochloric Acid e.g.
Use Marble chips
then more crushed marble chips
then Chalk.
Use the same amounts of CaCO3 and HCL each time.

Question 11

What does the steepness of the graph gradient indicate

Answer 11

Faster reaction - Steeper Gradient = faster reaction

Question 12

why does changing the concentration of the reactant speed up reaction?

Answer 12

More reactant particles can collide with the product.

Question 13

Name an experiment to test how temperature affects the rate of reaction

Answer 13

Use Sodium Thiosulphate and Hydrochloric Acid. The are both clear and colourless and when the react together they form a yellow precipitate of sulphur

Question 14

Explain the precipitation experiment to show temperature effects rates of reaction

Answer 14

1. Measure fixed volumes of Sodium Thiosulfate and HCL
2. Use a water bath to gently heat both solutions to the desired temp before you mix them
3. Mix the solutions
4. Place the flask on a piece paper marks with a black mark
5. Measure the time it takes for the mark to disappear
6. repeat the experiment at different temperatures

Question 15

What is important when conducting rate of reactions experiment

Answer 15

1. Volume of the product is the same
2. Amount of the reactant is the same
3. Only change on variable at a time e.g. time or concentration or size of particle

Question 16

What does the gradient of the rate of reaction graph indicate?

Answer 16

Steeper Gradient = faster rate of reaction

Question 17

What is the gradient calculation?

Answer 17

Gradient = change in y divided by change in X

Question 18

How to work out the change in Y

Answer 18

Pick two points on a graph - Draw a line straight done from the high point and then straight across (making a triangle). Read both figures from the Y axis (up) and take them away from each other

Question 19

How do you work out the change in x

Answer 19

On the same triangle then read the first point on the x axis and the second. Take the figures away from each other.

Question 20

What is collision thoery?

Answer 20

The is the rate of reaction

Question 21

What does the reaction depend on?

Answer 21

The collision frequency of reacting particles (how often they collide)
The energy transferred during the collision. The minimum energy that particles need to react when they collide is called activation energy. Particle need to collide with at least the activation energy for the collision to be successful

Question 22

What does more collision equal

Answer 22

higher rate of reactions

Question 23

Why does temperature increase the reaction rate?

Answer 23

The particle move faster and there more collisions. Higher temperatures increase the energy of the collisions - reactions only happen if the particles collide with enough energy

Question 24

Why does increasing concentration increase reaction rate

Answer 24

If the solution in more concentrated then there are more particles of reactant in the same volume. In gas the increase in pressure means the particles are more crowded = increase in collision

Question 25

What does smaller particle (more surface area) increase reaction rate

Answer 25

The particles have move area to work on - more collisions = in crease in reaction rate.