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IGCSE umaima > Chemistry theory > Flashcards

Chemistry theory Flashcards

(69 cards)

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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
sources of sulfur
petrolium, ores, natural state
26
name a polyester
terelyne
27
properties of alkanes
- substitution reaction with halogens and UV light - combustion - cracking
28
hyrdation
ethene + steam = ethanol phosphoric acid 300 and 60 atm
29
define compound
two or more elements chemically combine together
30
raw materials added to iron blast furnace
hot air, coke, hematite, limestone
31
how to make steel from iron
pass oxygen through iron to control the carbon content and let it escape in the form of carbon dioxide
32
Photochemical reactions
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
Silver salts in photography
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
role of chlorophyll in photosynthesis
a catalyst
35
polyethene
made of one type of unit/monomer | polyethene - low density plastic bags/ plastic bottles high density
36
polypropene
food packages, ropes, carpets
37
polycholroethene PVC
pipes, insulation on wires
38
Hydrolysis of proteins
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
what catalyst is used in fermentation
Yeast contains zymase enzymes (biological catalysts) that break down starch or sugar to glucose
40
chromotagraphy of organic compounds
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
difference between substitution and addition reaction
in addition inly one product forms and only happens in alkenes
42
how are carboxylic acids formed
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
Lubricating oil
polishes, waxes, lubricants
44
fuel oil
fuel for ships and for home heating
45
kerosene/paraffin
Kerosene: for making jet fuel (paraffin)
46
what is the temperature range for farctional distillation of petrolium
25-350
47
define relative atomic mass
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
define relative molecular mass
he sum | of the relative atomic masses.
49
avogadro's constant
One Mole is the amount of a substance that contains 6 x 1023 particles
50
define mole
The mass of substance containing the same number of units as there are atoms in exactly 12.000 g of 12C.
51
carbonate ion has a charge of
2+
52
ammonium has a charge of
4+
53
ammonia has a charge of
1+
54
Describe, in outline, the usefulness of chromatography in separating and identifying the products of hydrolysis of carbohydrates and proteins
idenitify monomers and Rf value, breaks it down hydrolysis water.
55
nylon
nets rope fabric | poly amide
56
why does the color of the copper solution stay the same in copper purification
copper is both added and removed at the same rate | the concentration of the copper ions does not change.
57
what is the mass of an electron
1/1840
58
give a use of - naoh - short chain alkanes - alkenes - hydrogen
- detergents - fuel - alcohol - fuel cells
59
give a property of homologous series
- each member differs by CH2 | - molecular members differ by 12
60
name two other fertilizers commonly found for plant growth
- potassium | - phosphates
61
what is meant by the term fuel
substance burnt to release energy/heat | fractions of petroleum count as fossil fuels
62
what does cracking of alkane gives us?
1. alkene + alkane | 2. alkene + alkene + hydrogen
63
name the catalyst needed to form an ester from ethanoic acid and methanol
concentrated sulfuric acid
64
Properties of group 1 elements
- reactivity increases down the group - m.p and b.p decrease down the group - density increases down the group
65
Composition of bronze
Copper and tin
66
Composition of stainless steel
Iron Chromium Nickel
67
Thermal decomposition of Metal hydroxides
Metal oxide + water | Except potassium and sodium
68
Thermal decomposition of metal nitrates
Nitrogen dioxide + oxygen + metal oxide For potassium and sodium Metal nitrite + oxygen
69
Which element does not form a stable ion with the same electronic structure as argon
Aluminum

IGCSE umaima (9 decks)

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