Chemical Reactions

Question 1

Fill in the missing words in these indicators of a chemical reaction:
Production of a _____, effervesense (_______ or bubbling).
Temperature ________.
_______ of light.
________ colour change.
Formation of a _________ (an insoluble solid formed from solutions)

Answer 1

Production of a GAS, effervesense (FIZZING or bubbling).
Temperature CHANGE.
PRODUCTION of light.
PERMANENT colour change.
Formation of a PRECIPITATE (an insoluble solid formed from solutions)

Question 2

During a chemical reaction atoms are rearranged to form what?

Answer 2

different compounds or elements and compounds.

Question 3

what scale is used to show the strength of acids and alkalis?

Answer 3

PH scale

Question 4

what is the range on the pH scale of acids?

Answer 4

0 - 6

Question 5

Is 6 on the pH scale a strong or weak acid?

Answer 5

weak acid

Question 6

what is the range on the pH scale of alkalis?

Answer 6

8-14

Question 7

is 13 on the pH a strong Acid or Alkali?

Answer 7

Alkali

Question 8

What number on the pH scale represents a neutral substance?

Answer 8

7

Question 9

what is added to a liquid to give a pH reading?

Answer 9

colour universal indicator

Question 10

what does pH stand for?

Answer 10

potential of Hydrogen

Question 11

give 2 examples of common acids

Answer 11

lemon, vinegar, orange juice

Question 12

give 2 examples of common alkalis found in a home

Answer 12

bleach, soap, baking soda

Question 13

where on the pH scale would tap water commonly sit?

Answer 13

pH 7

Question 14

where on the pH scale would stomach acid commonly sit and would the indicator give a red or purple result?

Answer 14

pH 1 - strong red

Question 15

what colour would a substance that is neutral on the pH scale usually turn with universal indicator

Answer 15

Green

Question 16

what type of reaction is described here:

A chemical reaction where an acid reacts with an alkali to form salt and water.

Answer 16

Neutralisation reaction

Question 17

what is the general word equation for a neutralisation reaction?

Answer 17

Acid + Alkali —-> Salt + Water

Question 18

When naming salts formed in neutralisation reactions does the first word come from the acid or the alkali?

Answer 18

Alkali, the second word comes from the acid.

Question 19

what are the the products from this reaction:

Hydrochloric Acid + Sodium Hydroxide

Answer 19

—-> Sodium Chloride + Water

Question 20

When a substance is burned in air what element from the air is it reacting with?

Answer 20

Oxygen

Question 21

What colour flame is produced when magnesium is burned in air?

Answer 21

bright white

Question 22

what are the 3 indicators that a chemical reaction is taking place when magnesium is burned in air?

Answer 22

1. production of light, 2. temperature change, 3. change in appearance.

Question 23

what is produced when magnesium is burned and reacts with oxygen?

Answer 23

Magnesium + Oxygen —> Magnesium Oxide

Question 24

what is the product of this reaction:

2Mg + O2

Answer 24

2MgO

Question 25

Describe combustion

Answer 25

fuel is burned in oxygen to release light and energy

Question 26

What 3 things are needed for combustion to take place?

Answer 26

1. Oxygen, 2. Heat, 3. Fuel

Question 27

What is a compound of Hydrogen and Carbon called

Answer 27

Hydrocarbon

Question 28

what is the word equation to describe complete combustion of a hydrocarbon

Answer 28

Hydrocarbon + Oxygen ---> Carbon Dioxide + Water

Question 29

Is complete or incomplete combustion used to describe the process of a Hydrocarbon burning in limited oxygen?

Answer 29

Incomplete

Question 30

Is complete or incomplete combustion used to describe the process of a Hydrocarbon burning in excess oxygen?

Answer 30

Complete

Question 31

What is produced when incomplete combustion of a hydrocarbon take place?

Answer 31

either CO (Carbon Monoxide) + Water, or C (Carbon) + Water

Question 32

What is the name of a reaction that releases energy as either heat or light?

Answer 32

Exothermic

Question 33

Why are some reactions exothermic

Answer 33

the total energy of the product is less than the total energy of the reactants.

Question 34

Describe endothermic reactions

Answer 34

Reactions that take in energy from the surroundings

Question 35

Is mass lost or gained in chemical reactions?

Answer 35

No - no mass is lost or gained.

Question 36

What is the common name for the gaining of oxygen in a chemical reaction?

Answer 36

Oxidation

Question 37

what is described here: | A substance reacts and combines with Oxygen.

Answer 37

An oxidation reaction.

Question 38

is combustion an oxidation reaction?

Answer 38

Yes

Question 39

Give an (not combustion) example of a common oxidation reaction

Answer 39

Rusting

Question 40

In rusting what element is reacting with the Oxygen in the air?

Answer 40

Iron to form Iron oxide.

Question 41

Give the word formula for rusting

Answer 41

Iron + Oxygen ---> Iron Oxide