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IGCSE umaima > Chemistry theory > Flashcards

Chemistry theory Flashcards

1
Q

simplify the extraction of zinc in three steps

A
  1. zinc blende (ZnS) is roasted in the presence of air
    2ZnS(s) + 3O2(g) -> 2ZnO + 2SO2
  2. Zinc Oxide is reduced by coke
  3. zinc is in a gaseous state so is condensed and distilled and leaves at the top
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2
Q

composition of brass

A

zinc and copper

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3
Q

test for water

A

anhydrous copper (II) sulphate changes from white to blue

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4
Q

Name the compounds of magnesium that form magnesium oxide when heated

A

Magnesium Nitrate, Magnesium Carbonate and Magnesium Hydroxide

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5
Q

Sulfur dioxide, Sulfur dioxide, SO2, is used in the manufacture of sulfuric acid. In the first stage of the process, sulfur dioxide is obtained from sulfur-containing ores.
Name one of these ores.

A

Zinc Blende

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6
Q

state the uses of sulfuric acid

A

detergents, dyes, car batteries , paints , dehydrating agent

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7
Q

A bottle of liquid perfume is left open at the front of a room.
After some time, the perfume is smelt at the back of the room.
Name the two physical processes taking place.

A

diffusion and evaporation

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8
Q

Iron forms hydrated iron(III) oxide when it rusts.

Write a word equation to represent the formation of rust.

A

iron
+ water + oxygen
 (hydrated) iron oxide

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9
Q

Items made from nylon are often disposed of by burying them in the ground. This is called
landfill.
Why is the disposal of nylon using landfill a problem?

A

non bio degradeable

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10
Q

What difference in the molecules of gasoline and kerosene causes these differences in
properties?

A

kerosene has molecules with a longer carbon chain

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11
Q

Suggest one benefit to the environment of reducing the operating temperature in electrolysis of AL

A

less CO2 emission

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12
Q

Are Ionic compounds soluble in water?

A

Yes

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13
Q

What is the role of potassium manganate(VII) in this reaction?
What condition must be used for this reaction to occur?

A

acid

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14
Q

name a polyamide

A

nylon two different monomers are NH2 and COOH

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15
Q

fractional distillation of petrollium

A
  1. Refinery Gas (ranjta)
  2. Gasoline (goes)
  3. Naphtha (new york)
  4. kerosene (kant)
  5. Deisel (dream)
  6. Fuel Oil (for)
  7. Lubricating oil (liberty)
  8. Bitumean (boy)
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16
Q

give a use of SO2

A

to bleach wood pulp, a food preservative (they kill bacteria) often added to food in the form of sulfites which then release so2 , making sulfuric acid

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17
Q

uses of ethanol

A

as a solvent and as fuel

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18
Q

why do covalent compounds have low melting points

A

weak forces of attraction intermolecular forces which require little energy to break

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19
Q

define base

A

proton acceptor H+

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20
Q

how do we know if a reaction stopped?

A
  1. no more effervesence

2. stops dissolving

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21
Q

define saturated solution

A

contains maximum of dissovled solute at any given temperature

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22
Q

why shouldnt we heat crystals to dryness

A

it would remove water of crystallisation

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23
Q

what happens when sodium reacts with water

A

rapid, fizzing, forms a shiny ball and floats

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24
Q

explain how nitrogen dioxide is formed in car engines

A

nitrogen and oxygen from the atmosphere react at high temperatures in the engine through an electrical spark in the engine.

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25
Q

sources of sulfur

A

petrolium, ores, natural state

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26
Q

name a polyester

A

terelyne

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27
Q

properties of alkanes

A
  • substitution reaction with halogens and UV light
  • combustion
  • cracking
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28
Q

hyrdation

A

ethene + steam = ethanol
phosphoric acid
300 and 60 atm

29
Q

define compound

A

two or more elements chemically combine together

30
Q

raw materials added to iron blast furnace

A

hot air, coke, hematite, limestone

31
Q

how to make steel from iron

A

pass oxygen through iron to control the carbon content and let it escape in the form of carbon dioxide

32
Q

Photochemical reactions

A

These reactions occur only when light is present
The greater the intensity of ultraviolet light then the greater the rate of reaction
Eg the substitution of hydrogen atoms in methane by chlorine
CH4 + Cl2 → CH3Cl + HCl

33
Q

Silver salts in photography

A

Black and white photography film surfaces contain crystals of silver bromide
When exposed to light they decompose to silver:
2AgBr → 2Ag + Br2
AgBr is colourless at low concentrations but the Ag appears grey-black
Parts of the film appear black, grey or white depending on the exposure:
Stronger light = black or dark grey
Weaker light = light grey
Not exposed = white

34
Q

role of chlorophyll in photosynthesis

A

a catalyst

35
Q

polyethene

A

made of one type of unit/monomer

polyethene - low density plastic bags/ plastic bottles high density

36
Q

polypropene

A

food packages, ropes, carpets

37
Q

polycholroethene PVC

A

pipes, insulation on wires

38
Q

Hydrolysis of proteins

A

Proteins can be hydrolysed by the addition of water in acidic or alkaline conditions
Heat and concentrated acid (usually 6 mol/dm3 HCl) are used with a reflux condenser to prevent the acidic vapours from escaping the reaction vessel
Aqueous ammonia is added after completion to neutralise the excess acid
Enzymes can also be used to hydrolyse some proteins at room temperature, mimicking natural bodily processes

39
Q

what catalyst is used in fermentation

A

Yeast contains zymase enzymes (biological catalysts) that break down starch or sugar to glucose

40
Q

chromotagraphy of organic compounds

A

In this technique a run is carried out in one direction, then the paper is rotated by 90º and performed again using a different solvent
This further separates sample spots that may not have separated in the first run
The resulting chromatogram is dried and sprayed with a locating agent
The Rf value of each solvent used is characteristic for each sugar or amino acid

41
Q

difference between substitution and addition reaction

A

in addition inly one product forms and only happens in alkenes

42
Q

how are carboxylic acids formed

A

oxidation of alcohol through acidified potassium manganate or the microbial oxidation of ethanol/wine. h2o is the end product. bacteria in the air will use oxygen in the atmosphere the oxidize he opened bottle of wine

43
Q

Lubricating oil

A

polishes, waxes, lubricants

44
Q

fuel oil

A

fuel for ships and for home heating

45
Q

kerosene/paraffin

A

Kerosene: for making jet fuel (paraffin)

46
Q

what is the temperature range for farctional distillation of petrolium

A

25-350

47
Q

define relative atomic mass

A

the average mass of naturally occurring atoms of an element on a scale where the 12C atom has a mass of
exactly 12 units

48
Q

define relative molecular mass

A

he sum

of the relative atomic masses.

49
Q

avogadro’s constant

A

One Mole is the amount of a substance that contains 6 x 1023 particles

50
Q

define mole

A

The mass of substance containing the same number of units as there are atoms in exactly 12.000 g of 12C.

51
Q

carbonate ion has a charge of

A

2+

52
Q

ammonium has a charge of

A

4+

53
Q

ammonia has a charge of

A

1+

54
Q

Describe, in outline, the usefulness of chromatography in
separating and identifying the products of hydrolysis of
carbohydrates and proteins

A

idenitify monomers and Rf value, breaks it down hydrolysis water.

55
Q

nylon

A

nets rope fabric

poly amide

56
Q

why does the color of the copper solution stay the same in copper purification

A

copper is both added and removed at the same rate

the concentration of the copper ions does not change.

57
Q

what is the mass of an electron

A

1/1840

58
Q

give a use of

  • naoh
  • short chain alkanes
  • alkenes
  • hydrogen
A
  • detergents
  • fuel
  • alcohol
  • fuel cells
59
Q

give a property of homologous series

A
  • each member differs by CH2

- molecular members differ by 12

60
Q

name two other fertilizers commonly found for plant growth

A
  • potassium

- phosphates

61
Q

what is meant by the term fuel

A

substance burnt to release energy/heat

fractions of petroleum count as fossil fuels

62
Q

what does cracking of alkane gives us?

A
  1. alkene + alkane

2. alkene + alkene + hydrogen

63
Q

name the catalyst needed to form an ester from ethanoic acid and methanol

A

concentrated sulfuric acid

64
Q

Properties of group 1 elements

A
  • reactivity increases down the group
  • m.p and b.p decrease down the group
  • density increases down the group
65
Q

Composition of bronze

A

Copper and tin

66
Q

Composition of stainless steel

A

Iron
Chromium
Nickel

67
Q

Thermal decomposition of Metal hydroxides

A

Metal oxide + water

Except potassium and sodium

68
Q

Thermal decomposition of metal nitrates

A

Nitrogen dioxide + oxygen + metal oxide

For potassium and sodium
Metal nitrite + oxygen

69
Q

Which element does not form a stable ion with the same electronic structure as argon

A

Aluminum

IGCSE umaima (9 decks)

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