Chemistry theory Flashcards
simplify the extraction of zinc in three steps
- zinc blende (ZnS) is roasted in the presence of air
2ZnS(s) + 3O2(g) -> 2ZnO + 2SO2 - Zinc Oxide is reduced by coke
- zinc is in a gaseous state so is condensed and distilled and leaves at the top
composition of brass
zinc and copper
test for water
anhydrous copper (II) sulphate changes from white to blue
Name the compounds of magnesium that form magnesium oxide when heated
Magnesium Nitrate, Magnesium Carbonate and Magnesium Hydroxide
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.
Zinc Blende
state the uses of sulfuric acid
detergents, dyes, car batteries , paints , dehydrating agent
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.
diffusion and evaporation
Iron forms hydrated iron(III) oxide when it rusts.
Write a word equation to represent the formation of rust.
iron
+ water + oxygen
(hydrated) iron oxide
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?
non bio degradeable
What difference in the molecules of gasoline and kerosene causes these differences in
properties?
kerosene has molecules with a longer carbon chain
Suggest one benefit to the environment of reducing the operating temperature in electrolysis of AL
less CO2 emission
Are Ionic compounds soluble in water?
Yes
What is the role of potassium manganate(VII) in this reaction?
What condition must be used for this reaction to occur?
acid
name a polyamide
nylon two different monomers are NH2 and COOH
fractional distillation of petrollium
- Refinery Gas (ranjta)
- Gasoline (goes)
- Naphtha (new york)
- kerosene (kant)
- Deisel (dream)
- Fuel Oil (for)
- Lubricating oil (liberty)
- Bitumean (boy)
give a use of SO2
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
uses of ethanol
as a solvent and as fuel
why do covalent compounds have low melting points
weak forces of attraction intermolecular forces which require little energy to break
define base
proton acceptor H+
how do we know if a reaction stopped?
- no more effervesence
2. stops dissolving
define saturated solution
contains maximum of dissovled solute at any given temperature
why shouldnt we heat crystals to dryness
it would remove water of crystallisation
what happens when sodium reacts with water
rapid, fizzing, forms a shiny ball and floats
explain how nitrogen dioxide is formed in car engines
nitrogen and oxygen from the atmosphere react at high temperatures in the engine through an electrical spark in the engine.
sources of sulfur
petrolium, ores, natural state
name a polyester
terelyne
properties of alkanes
- substitution reaction with halogens and UV light
- combustion
- cracking
hyrdation
ethene + steam = ethanol
phosphoric acid
300 and 60 atm
define compound
two or more elements chemically combine together
raw materials added to iron blast furnace
hot air, coke, hematite, limestone
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
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
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
role of chlorophyll in photosynthesis
a catalyst
polyethene
made of one type of unit/monomer
polyethene - low density plastic bags/ plastic bottles high density
polypropene
food packages, ropes, carpets
polycholroethene PVC
pipes, insulation on wires
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
what catalyst is used in fermentation
Yeast contains zymase enzymes (biological catalysts) that break down starch or sugar to glucose
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
difference between substitution and addition reaction
in addition inly one product forms and only happens in alkenes
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
Lubricating oil
polishes, waxes, lubricants
fuel oil
fuel for ships and for home heating
kerosene/paraffin
Kerosene: for making jet fuel (paraffin)
what is the temperature range for farctional distillation of petrolium
25-350
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
define relative molecular mass
he sum
of the relative atomic masses.
avogadro’s constant
One Mole is the amount of a substance that contains 6 x 1023 particles
define mole
The mass of substance containing the same number of units as there are atoms in exactly 12.000 g of 12C.
carbonate ion has a charge of
2+
ammonium has a charge of
4+
ammonia has a charge of
1+
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.
nylon
nets rope fabric
poly amide
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.
what is the mass of an electron
1/1840
give a use of
- naoh
- short chain alkanes
- alkenes
- hydrogen
- detergents
- fuel
- alcohol
- fuel cells
give a property of homologous series
- each member differs by CH2
- molecular members differ by 12
name two other fertilizers commonly found for plant growth
- potassium
- phosphates
what is meant by the term fuel
substance burnt to release energy/heat
fractions of petroleum count as fossil fuels
what does cracking of alkane gives us?
- alkene + alkane
2. alkene + alkene + hydrogen
name the catalyst needed to form an ester from ethanoic acid and methanol
concentrated sulfuric acid
Properties of group 1 elements
- reactivity increases down the group
- m.p and b.p decrease down the group
- density increases down the group
Composition of bronze
Copper and tin
Composition of stainless steel
Iron
Chromium
Nickel
Thermal decomposition of Metal hydroxides
Metal oxide + water
Except potassium and sodium
Thermal decomposition of metal nitrates
Nitrogen dioxide + oxygen + metal oxide
For potassium and sodium
Metal nitrite + oxygen
Which element does not form a stable ion with the same electronic structure as argon
Aluminum
