Rates Of Reaction

Question 1

What is the equation for the rate of reaction?

Answer 1

1/ Average time

Average time = Time 1 + Time 2 / 2

Rate = Change in a measured quantity / time taken

Question 2

Explain collision theory?

Answer 2

For a reaction to take place between reacting particles it must:

1. Have a successful collision
2. Have enough energy to react

Question 3

What is activation energy?

Answer 3

The minimum amount of energy needed to for a chemical reaction to occur.

Question 4

How does increasing the surface area affect the rate of reaction?

Answer 4

• More particles are exposed to the other reactants
• Meaning there are more successful collisions in a given time period
• Increases the rate of reaction

Question 5

Diagram for measuring the rate of reaction

Answer 5

Look in book!

Question 6

What are the properties of carbon dioxide?

Answer 6

• odourless gas
• Colourless gas
• Heavier than air
• When cooled to -78 degrees it sublimes into dry ice
• It does not support combustion
• It is slightly soluble in water giving an acidic solution

Question 7

Explain the combustion of carbon when there are different supplies of oxygen?

Answer 7

Complete combustion - Plentiful supply
Carbon + Oxygen = Carbon dioxide

Incomplete combustion - Limited supply
Carbon + Oxygen = Carbon Monoxide

Question 8

Properties of carbon monoxide?

Answer 8

• Toxic
• Colourless
• Odourless gas

Question 9

What are some uses of carbon dioxide?

Answer 9

• Fire extinguishers - does not aid combustion
• Carbonated drinks - soluble in water and dissolved under high pressure
• Dry ice via sublimation

Question 10

Diagram for the preparation of carbon dioxide?

Answer 10

Look in book :]

Question 11

How does temperature effect the rate of reaction?

Answer 11

At the temp increases, the particles gain energy and move faster, leading to more successful collisions in a given period of time.

The rate of reaction increases

Question 12

What is a catalyst?

Answer 12

A catalyst is a substance that can increase the rate of a reaction.

The catalyst itself remains unchanged at the end of the reaction it catalyses.

Question 13

How does a catalyst increase the rate of reaction?

Answer 13

As it provides an alternative pathway with a lower activation energy

Question 14

Example of a catalyst?

Answer 14

Hydrogen peroxide will decompose to form water and oxygen:
Hydrogen peroxide –> water + oxygen

The reaction is extremely slow but can be speeded up using a catalyst called MANGANESE(IV) OXIDE.

Question 15

What is the test for oxygen?

Answer 15

Relights a glowing splint

Question 15

What are the properties of oxygen?

Answer 15

• Colourless, odourless gas
• Slightly soluble in water
• It is neutral
• It is very reactive. Will react with many substances to form the oxides

Question 16

What are uses of oxygen?

Answer 16

• Medicine
• welding
• Rocket Engines
• Steel Making

Question 17

What are the observations of the reaction of oxygen with Magnesium?

Answer 17

Grey magnesium burns with a bright white flame producing a white ash of magnesium oxide. The solid is a basic oxide.

Question 18

What are the observations of the reaction of oxygen with Cooper

Answer 18

Red-brown solid glows red when heated and a blue-green flame is produced. A black layer of basic copper oxide is formed.

Question 19

What are the observations of the reaction of oxygen with Iron

Answer 19

Grey solid burns with orange sparks. A black basic oxide is formed.

Question 20

What are the observations of the reaction of oxygen with Sulphur

Answer 20

Yellow solid melts to form a viscous brown liquid. This burns with a blue flame to produce the pungent smelling acidic sulfur dioxide gas.

Question 21

What are the observations of the reaction of oxygen with Carbon

Answer 21

Carbon monoxide produced in a limited supply

Carbon dioxide produced in a plentiful supply

Black carbon burns with orange sparks producing an acidic colourless gas

Question 22

What are the properties of Hydrogen?

Answer 22

• Colourless, Odourless Gas
• Insoluble in Water
• Less dense than air
• Neutral

Question 23

What is the test for Hydrogen?

Answer 23

Squeaky pop when a lit splint is put in a test tube

Question 24

Uses of hydrogen and their reasons?

Answer 24

Meteorological Balloons - less dense than air

Hardening Oils - can convert unsaturated vegetable oils into solid at room temperature

Potential Clean Fuels - reacts with oxygen only producing water

Question 25

What are the observations of the reaction of Hydrogen with Oxygen

Answer 25

Hydrogen + Oxygen –> Water

Oxygen is reduced as it gains hydrogen.

Hydrogen is the reducing agent as it has caused the reduction to take place.

Question 26

What are the observations of the reaction of Hydrogen with Copper Oxide

Answer 26

Hydrogen acts as the reducing agent and reduces copper oxide to copper.

Copper oxide + Hydrogen –> Copper + Water

Question 27

What are the observations of the reaction of Hydrogen with Nitrogen

Answer 27

Nitrogen is a very unreactive element and will react with very few other elements.

It will however react with hydrogen to produce ammonia in a process known as the Haber Process.

Nitrogen + Hydrogen  Ammonia

Question 28

How does concentration increase the rate of reaction?

Answer 28

The higher the concentration the higher the rate of reaction as there are more acid particles to successfully collide with in a given period of time.