Gas preparations

Question 1

Distribution of the mixture of our air

Answer 1

Nitrogen (78%)
Oxygen (21%)
Argon (0.97%)
Carbon dioxide (0.03%)

Question 2

What process do we use to separate air and how does it work?

Answer 2

Fractional Distillation - condense air into liquids, heat mixture, and evaporate based on bpt.

Question 3

Metal + acid –>

Answer 3

salt + hydrogen

Question 4

Properties of hydrogen

Answer 4

• soluble in oil like substances (insoluble in water)
• doesn’t conduct
• low mpt/bpt

Question 5

For Hydrogen:
Solid in the beaker

Answer 5

Magnesium or Zinc

Question 6

For Hydrogen:
liquid in separating funnel

Answer 6

Hydrochloric acid

Question 7

Reactions of Mg/Zn with hydrochloric acid?

Answer 7

Mg + 2HCL –> MgCl₂ + H₂
Zn + 2HCL –> ZnCl₂ + H₂

Question 8

Reaction for hydrogen =

Answer 8

H₂ + O₂ –> H₂O (g) exothermic reaction!

Question 9

Test for hydrogen =

Answer 9

Burning/lit splint –> explodes with pop

Question 10

Reaction for oxygen =

Answer 10

H₂O₂ –>H₂O + O₂

Question 11

test for oxygen=

Answer 11

glowing splint –> split will reignite

Question 12

How is maganese (IV) used in the seperation of oxygen?

Answer 12

Its a solid at the bottom of the conical flask, and acts as a catalyst for the reaction.

Question 13

Liquid in the separating funnel during oxygen reaction

Answer 13

H₂O₂ - used through decomposition

Question 14

What is meant by water displacement?

Answer 14

If a gas is insoluble in water, it will not react, and we can use water (in a trough) to collect gas particles

Question 15

Test for carbon dioxide =

Answer 15

Limewater/ colourless –> cloudy if CO₂ is present

Question 16

what is limewater?

Answer 16

an aqueous solution of calcium hydroxide

Question 17

Solid in the conical flask for carbon dioxide reaction?

Answer 17

Calcium carbonate (CaCO₃)

Question 18

liquid in the separating funnel for carbon dioxide reaction?

Answer 18

Hydrochloric acid (HCL)

Question 19

Reaction for carbon dioxide process:

Answer 19

CaCO₃ + HCL —> CaCL₂ (stays in solution) +H₂O + CO₂

Question 20

Why is magnesium or zinc used as the solid in the gas preparation for hydrogen?

Answer 20

When Mg or Zn react with acids (in this case HCL) they produce hydrogen gas. (Metal + acid –> salt and hydrogen!)
Both Mg and Zn are more reactive that hydrogen, making the displacement reaction with acids easier. (Mn or Zn displace hydrogen in acid to form a metal salt and hydrogen)

Question 21

Solid at bottom of test tube in Chlorine reaction:

Answer 21

Manganese oxide

Question 22

Liquid used in chlorine reaction:

Answer 22

Hydrochloric acid (HCL)

Question 23

Reaction for chlorine:

Answer 23

MnO₂ + HCL –> MnCL₂ + H₂O + Cl₂

Question 24

test for chlorine

Answer 24

damp blue litmus paper/ red –> white (indicating acid)

Question 25

Why is chlorine not collected through water displacement?

Answer 25

1) It reacts with water to form HCL and HOCL

Question 26

What is downward delivery (as used in chlorine)?

Answer 26

Chlorine is denser than air, and can be collected by “delivering it downward” the delivery tube is pointed downward into a test tube instead of a trough of water