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Flashcards in Chemistry IGCSE Deck (57)
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1
Q

moles of substance?

A

moles = mass / Mr

2
Q

moles of a gas (standard temperature and pressure)?

A

moles = Volume / 24 dm^3

3
Q

moles of an aqueous solution?

A

moles = Volume x concentration

4
Q

What two substances could be produced at the anode of the electrolysis of an aqueous substance?

A

Oxygen or a non-metal

5
Q

Name three experiments to find oxygen concentration in air

A

Copper; Iron filings; Phosphorus

6
Q

Sulphur + oxygen

A

sulphur dioxide (colourless) and lilac flame

7
Q

Describe lab preparation of carbon dioxide

A

Put hydrochloric acid and calcium carbonate in a test tube with a bung with a tube which goes into limewater; if the gas produced (bubbling) is CO2, the limewater will turn cloudy, forming CaCO3 precipitates

8
Q

What is observed when heating CuCO3?

A

CuCO3 decomposes into BLACK CuO (copper (II) oxide) and CO2 gas

9
Q

What is observed when ZnCO3 is heated?

A

Colour change; white to yellow; ZnCO3 -> ZnO + CO2

10
Q

Describe manufacture of ethanol by hydration of ethene

A

Ethene passed over steam with Phosphoric acid catalyst. 300°C, 60-70 atm.

11
Q

Describe dehydration of ethanol to produce ethene

A

Pass ethanol over hot aluminium oxide catalyst

12
Q

Phenolphtalein in acid

A

colourless

13
Q

Methyl orange in alkali

A

yellow

14
Q

Methyl orange in acid

A

red/orange

15
Q

Methyl orange in neutral

A

yellow

16
Q

Phenolphtalein in alkali

A

pink

17
Q

Phenolphtalein in neutral

A

colourless

18
Q

Litmus in Acid

A

red

19
Q

Litmus in alkali

A

blue

20
Q

Litmus in neutral

A

purple

21
Q

Which salts are soluble?

A

Nitrates, Sodium/Potassium/Ammonium salts

22
Q

Which chlorides are insoluble?

A

Silver chloride, Lead chloride

23
Q

Which sulfates are insoluble?

A

Barium sulfate, calcium sulfate, lead sulfate

24
Q

Are carbonates soluble or insoluble?

A

Most are insoluble (e.g. Calcium carbonate)

25
Q

How do you make a soluble salt?

A

dilute acid + base; dilute acid + metal carbonate; dilute acid + metal

26
Q

How do you make insoluble salts?

A

Precipitations

27
Q

Is breaking bonds exo/endothermic?

A

ENDOTHERMIC

28
Q

Is making bonds exo/endothermic?

A

EXOTHERMIC

29
Q

Conditions for Haber process?

A

450°C, 200 atm, Iron catalyst

30
Q

Conditions for contact process?

A

450°C, 2 atm, Vanadium oxide catalyst

31
Q

Give three uses of sulfuric acid

A

fertilisers, paint, detergents

32
Q

Give four uses of NaOH (sodium hydroxide)

A

soap, bleach, detergent, paper

33
Q

How can you obtain NaOH and Chlorine?

A

Electrolysis of brine

34
Q

Describe Addition Polymerisation

A

An alkene monomer is bonded with other monomers to form a polymer. However, the alkene becomes an alkane.

35
Q

Describe Condensation Polymerisation

A

The monomers retain their bonds, but small molecules are lost; normally water, but sometimes NH3 or HCl

36
Q

Is Calcium Chloride (CaCl2) soluble or insoluble?

A

SOLUBLE

37
Q

Why do atoms in the same group of the periodic table have similar chemical properties?

A

Because they have the same number of valence electrons

38
Q

Give another name for the elements in group 1

A

the Alkali Metals

39
Q

How does Lithium react in water?

A

It moves on the surface of the water, it fizzes, melts and disappears

40
Q

How does Sodium react in water?

A

It moves on the surface of the water, it fizzes, melts into a shiny ball and then disappears

41
Q

How does Potassium react in water?

A

It moves on the surface of the water, it fizzes, melts into a shiny ball, produces a lilac flame, and eventually disappears.

42
Q

What happens to the reactivity of group 1 metals as you go down the periodic table?

A

They become more reactive.

43
Q

Why do group 1 metals become more reactive as you go down the periodic table?

A

Because the valence electron gets shielded by more shells further down the group, which decreases the electrostatic attraction between the valence electron and the nucleus, so it becomes easier for a metal further down to lose its valence electron and hence react.

44
Q

Name the halogens

A

Fluorine, Chlorine, Bromine, Iodine, Astatine

45
Q

What state and colour is chlorine at room temperature and pressure (rtp)?

A

Greenish gas

46
Q

What state and colour is bromine at rtp?

A

Brown/orange liquid

47
Q

What state and colour is iodine at rtp?

A

Black solid

48
Q

Explain the reactivity of the halogens

A

The reactivity decreases as you go down the periodic table because there is only one valence electron missing to make a full outer shell, and the further down the periodic table you go, the lesser the electrostatic attraction between the valence electrons and the nucleus, so much more energy would be needed to react.

49
Q

Why don’t HCl and methylbenzene form an acidic solution?

A

the H+ ions in HCl don’t ionise methylbenzene.

50
Q

What does the Brønsted-Lowry theory of acids and bases state?

A

That acids contain H+ ions, and hence are proton donors, and bases contain OH- ions, and hence are proton acceptors

51
Q

How do you determine atmospheric oxygen concentration using copper?

A

Attach two gas syringes to a silica tube (one on either side). Make sure that there are 100 cm^3 of air in the syringes. Place copper in the silica tube, and heat from below using a Bunsen burner. Pass the gas from one syringe to the other over the burning copper until the copper turns black (and becomes copper (II) oxide). Measure volume of gas syringes. It should be ~79cm^3, so 21% of gas was O2.

52
Q

How do you determine the atmospheric oxygen concentration using iron?

A

Put iron filings at bottom of a burette and place upside down in a trough of water. Measure starting volume of water. Leave for a week. Measure final volume of water. Difference should be ~21%

53
Q

What is formed when metal carbonates are heated (thermally decomposed)?

A

Carbon dioxide

54
Q

What do metals above Hydrogen in the reactivity series form when reacted with HCl?

A

Metal chloride + Hydrogen

55
Q

Metal + sulfuric acid?

A

metal + sulfuric acid –> metal sulfate + hydrogen

56
Q

List the elements of the reactivity series in decreasing reactivity

A

Potassium; Sodium; Lithium; Calcium; Magnesium; Aluminium; Zinc; Iron; Tin; Lead; Hydrogen; Copper; Silver; Gold; Platinum

57
Q

Useful mnemonic to remember reactivity series

A

Private Second-Class MACZITL He Can make Some Gun Powder