Planet Earth

Question 1

what is decantation

Answer 1

Decantation is a process to separate mixtures by removing a liquid layer that is free of a precipitate, or the solids deposited from a solution.
eg. sand from water

Question 2

how to determine a saturated solution

Answer 2

remove a drop of solution with glass rod

see whether solids form when drops cool

Question 3

why cold water is used to wash a crystal after crystallization

Answer 3

remove water-soluble im purities

help reduce loss of salt

Question 4

principle of simple distillation

Answer 4

water boils at 100.C but salts are non-volatile

steam formed condenses

Question 5

how to obtain dilute H2SO4 from concentrated H2SO4

Answer 5

concentrated sulphuric acid is added slowly into a large amount of water with constant stirring

Question 6

what is the function of the glass beads in the fractionating column

Answer 6

to provide a large surface area for condensation and evaporation of the mixture.

Question 7

daily application of neon

Answer 7

Gas for filling neon lights

Question 8

outline the underlying principle of simple distillation experiment

Answer 8

Water boils at about 100oC , but the salts in sea water are non-volatile
The steam formed condenses on the cold surface of the condenser to give liquid water.

Question 9

sodium is….

Answer 9

highly reactive

corrosive

Question 10

what is quicklime

Answer 10

CaO

Calcium oxide

Question 11

what is slaked lime

Answer 11

Ca(OH)2

Calcium hydroxide

Question 12

what is limewater

Answer 12

saturated calcium hydroxide solution

Question 13

what will thermal decomposition of metal carbonate give out

Answer 13

metal oxide and carbon dioxide

endothermic

Question 14

is sodium corrosive

Answer 14

yes

as it is alkali metal

Question 15

is conc. aqeous ammonia corrosive?

Answer 15

yes

as it is concentrated altho it is weak base

Question 16

fractional distillation of liquid air products

Answer 16

• 183 O2
• 186 Ar
• 196 N2

Question 17

advantage of using microscale experiment

Answer 17

save cost on chemicals
minimize chemical hazard
reduce chemical waste

Question 18

what are the sources of CaCO3

Answer 18

marble
limestone
chalk
egg shells

Question 19

state one natural source of silicon dioxide

Answer 19

sand/quartz

Question 20

state one industrial use of silicon dioxide

Answer 20

to make glass

Question 21

using the same amount of reactant, suggest how to increase the volume of liquid collected using the delivery tube and a test tube

Answer 21

immerse the test tube into a ice water bath to enhance the cooling effect

Question 22

what is relative isotopic mass

Answer 22

relative isotopic mass of an isotope of an element Is the mass of the atom on the C=12 scale

relative isotopic mass= mass of an atom of the element/ (1/12)(mass of an atom of carbon 12)

Question 23

what is relative atomic mass

Answer 23

relative atomic mass of an element is the average isotopic mass of all natural isotopes on the C=12 scale

Question 24

Aluminium is the most abundant element in the earth’s crust

T/F

Answer 24

F
its is the most abundant metal > Fe
but < O/N

Question 25

When distinguishing substance which are solids

Need to do what first

Answer 25

Dissolve the substance in deionised water first

Question 26

what is saturated solution

Answer 26

a solution containing the maximum amount of solute at a specific temperature