How Particle Size Affects Rate of Reaction

Question 1

How does one increase the surface area of a solid?

Answer 1

By dividing the solid into smaller pieces

Question 2

What is increased when a solid is divided into smaller pieces?

Answer 2

The surface area of the solid

Question 3

How does increased surface area affect rate of reaction?

Answer 3

The more surface area of the solid that is exposed to the reactants the faster a reaction will occur

Question 4

How does increasing the surface area of a solid increase the rate of reaction between the solid and reactants?

Answer 4

As more of the solid is exposed to the reactants

Question 5

What is an example of an experiment where increased surface area causes a faster rate of reaction?

Answer 5

The reaction of marble/calcium carbonate with dilute hydrochloric acid solution

Question 6

Describe how the reaction between marble/calcium carbonate and dilute hydrochloric acid solution is carried out.
7 key steps

Answer 6

1. 5g of powdered calcium carbonate is added to a conical flask
2. 50 cm cubed of hydrochloric acid solution is added to a graduated cylinder
3. The acid is poured into the conical flask containing the powdered calcium carbonate where it is swirled
4. A cotton wool plug is immediately added to the mouth of the conical flask and a stopwatch is started
5. The mass of the calcium carbonate is recorded at 30 second intervals until the reaction has stopped and bubbles are no longer produced
6. Repeat the experiment using the same mass of marble chips
7. Note that the reaction using the powdered calcium carbonate will take less time to reach completion that the marble chips experiment

Question 7

How much calcium carbonate is added to a conical flask?

Answer 7

5g

Question 8

What two forms of calcium carbonate are used in this experiment?

Answer 8

Powdered calcium carbonate

Marble chips

Question 9

During the first step of this experiment where is the 5g of calcium carbonate added?

Answer 9

To a conical flask

Question 10

What acid is used in this experiment?

Answer 10

Hydrochloric acid solution is used

Question 11

How much Hydrochloric acid solution is used in this experiment?

Answer 11

50 cm cubed

Question 12

In the second step of this experiment where is the 50 cm cubed of hydrochloric acid added?

Answer 12

A graduated cylinder

Question 13

In the third step of this experiment what is added to the conical flask of calcium carbonate?

Answer 13

The 50 cm cubed of hydrochloric acid is added

Question 14

What must immediately be done when the acid is added to the calcium carbonate?

Answer 14

A cotton wool plug must be placed in the neck of the conical flask
The conical flask must be swirled
A stopclock must be started

Question 15

At what intervals is the mass of the calcium carbonate recorded after the addition of acid?

Answer 15

At thirty second intervals

Question 16

Approximately how long will the experiment take?

Answer 16

10 minutes

Question 17

When is it clear the reaction has been completed?

Answer 17

When bubbles are no longer formed

Question 18

Why is a cotton wool plug used in this experiment?

Answer 18

The cotton allows for only the loss of carbon dioxide to affect the mass of the calcium carbonate

Question 19

What does the cotton wool plug allow to escape from the conical flask?

Answer 19

It allows Carbon Dioxide to escape

Question 20

What does the cotton wool plug not allow to escape from the conical flask?

Answer 20

It doesn’t allow acid spray formed as the marble reacts with the acid to escape

Question 21

What is the main problem when dealing with finely divided particles?

Answer 21

Dust explosions

Question 22

What type of particles cause a dust explosion?

Answer 22

Very small, energy-rich particles

Question 23

Give an example of a substance which can cause a dangerous dust explosion

Answer 23

Coal dust in a mine

Question 24

Give an example of a substance which can be used in a laboratory to create a controlled dust explosion

Answer 24

Lycopodium powder which is a type of very fine pollen

Question 25

Describe how lycopodium powder used to demonstrate a dust explosion.

Answer 25

The lycopodium powder is blown over a candle in a large coffee tin on which the lid has been firmly placed

Question 26

What 5 conditions are required for a dust explosion to take place?

Answer 26

An enclosed space
The particles must be combustible 
There must be a source of ignition 
The particles must be dry
There must be oxygen present