Reactions

Question 1

Testing for Water

Answer 1

A piece of cobalt chloride paper held in this gas will turn from blue to pink.

The condensation forming in the tube could be tested with CoCl2 paper, which would turn from blue to pink.

Question 2

Precipitation Reaction Definition

Answer 2

when the two solutions
are added together, an insoluble solid called a
precipitate forms

Question 3

How to describe precipitation reaction

Answer 3

When COLOUR COMPOUND solution is added to COLOUR COMPOUND solution, a COLOUR precipitate of COMPOUND forms and a COLOUR solution of COMPOUND.

Question 4

Testing solutions

Answer 4

Add drops of COMPOUND using a pipette to unknown solution in test tube

Question 5

Combination reaction

Answer 5

Two reactants combine to form a single product

Question 6

Displacement reaction definition

Answer 6

A more reactive metal on the activity series displaces a metal ion that is less reactive from its solution

Question 7

Catalytic Decomposition Observations

Answer 7

MnO2 - black
Iron (III) Chloride - yellow-orange

Colourless solution of hydrogen peroxide, black MnO2.

• bubbles of colourless oxygen gas
• warm
• produces a colourless liquid of water
• black solid remains

Question 8

Electron transfer.

Answer 8

Each ___ atom gains/loses electrons to form ___ ion.

COVALENT BONDING: ___ atoms gain 2 electrons to form two ions.

Oppositely charged ions attract to form an ionic bond/compound

Question 9

Magnesium Oxide Reaction

Answer 9

A grey strip of metal when heated in air, bursts into a bright white flame, producing a white powdery residue.

Question 10

Why do ions form?

Answer 10

Atoms are less stable than they are as ions, so metal atoms empty their valence electron shells by losing their electrons to non-metal atoms which gain electrons to fill their valence shell.

Question 11

Text for oxygen

Answer 11

Relights a glowing splint

Question 12

Test for hydrogen

Answer 12

Ignites a burning splint with a pop.

Question 13

Hydrogen and Oxygen reaction

Answer 13

Explode with a small flame and a loud squeaky pop would be heard. Condensation would form.

Question 14

Release of gas from powder

Answer 14

Some ‘jumping’ of the powder as colourless gas forms and escapes.

During heating, solids break up because gas escapes from them

Question 15

Why does a precipitate form?

Answer 15

A precipitate forms because the ions are attracted to each other in the solution.

Question 16

Spectator ions

Answer 16

Ions (compound) are soluble so precipitate does not form, and ions would be found on their own in the solution as spectator ions.

Question 17

Sodium carbonate (Na2CO3)

Answer 17

DOES NOT DECOMPOSE

Question 18

Sulfur reaction

Answer 18

Sulfur burns with a blue flame to make a colourless gas with a bad odour SO2

Question 19

Iron and sulfur

Answer 19

When heated, glows red and makes a non-magnetic solid of FeS

Question 20

Carbon + oxygen reaction

Answer 20

Carbon burns with a yellow flame to make a colourless gas CO2

Question 21

Iron wool (grey) reaction

Answer 21

Sparks are formed. After heating solid glows red and black solid, iron oxide is formed.

Question 22

Displacement reaction observations

Answer 22

• Deposit forms
• Colour of solution may change
• original metal slowly disappears.

Question 23

Why does it exist as a gas?

Answer 23

It is a covalent bond and the forces between the molecules are weak and easily broken at room temp.

Question 24

Why does it exist as a solid?

Answer 24

It contains ionic bonds and the forces between the ions are strong and room temp is not hot enough to overcome the forces.

Question 25

Why does it exist as a liquid?

Answer 25

Atoms or molecules have sufficient kinetic energy to overcome the chemical bonds that held them in their crystal lattice and move independently, but not enough to separate completely from other atoms