Chemistry

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  • Created by: florence
  • Created on: 05-03-13 19:00

safety

corrosive

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safety

flammable

(http://www.clker.com/cliparts/a/1/a/5/1242249442627091102Flammable-symbol.svg.med.png)

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safety

toxic

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safety

harmful/irritant

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safety

if your clothes catch fire:

.don't run around 
.lie down
.smother the flames
.roll around 

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safety

if you get alkali in your eye:

.run water over the eye
.get a friend to tell the teacher
.keep irrigating your eye
.go to hospital 

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safety

rules for specific situations

.clear floor
.don't eat in the lab
.wear goggles if needed
.wear a lab coat if needed
.keep tops on bottles unless pouring
.never hold or carry a bottle by it's neck
.tie hair back
.no loose clothing
.when a bunsen burner is not in use, close air-hole so a yellow flame can be seen
.don't point testubes at yourself or anyone else
.never look directly into a testube
.wash your hands after handling chemicals or biological materials
.put any waste solids in the special 'bits' bins 

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safety

if an accident happens:

.wipe up small accidents
.report big accidents to teacher
.if you get something in your mouth, spit it out and wash your mouth out with plenty of water
.if you are burnt or get a chemical on your skin, wash the effected skin with cold water
.report breakages to teacher
.broken glass should go in the special 'glass' bin 

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atmosphere

general info:

.the atmosphere is a mixture of gases that surrounds the earth

.the composition of todays atmosphere is very different from the composition of the earths early atmosphere which contained higher levels if H2O vapour and CO2, and very little O2

.the atmosphere we are currently living in is composed of 78% nitrogen, 21% oxygen and the remaining 1% contains many gases, including water vapour, COand argon.

.all the gases in the air have NO smell or colour

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atmosphere

nitrogen:

.main gas in atmosphere

.INSOBLUBE in water

.DOESN'T REACT EASILY with other substances (good incase of natural disasters; if it reacted badly with other substances it could make them worse)

.used to package food because it is mostly unreactive and insolube 

.however can react, used to make ammonia and nitric acid

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atmosphere

oxygen:

.REACTS WITH ALOT of substances

.SOLUBLE in water

.vital for life

.used for respiration (the process to release energy from sugars)

.is used in cylinder of gas in hospitals to help people with breathing problems 

.used to help substances burn better

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atmosphere

argon:

.VERY UNREACTIVE with other substances 

.INSOLUBLE in water 

.used to fill light bulbs so that the filiment doesn't burn out (because in is insoluble in water and very unreactive)

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atmosphere

carbon dioxide:

.FAIRLY UNREACTIVE with other substances

.INSOLUBLE in water

.used to assist green plants with photosynthesis because it is soluble in water and fairly unreactive

.sometimes used in fire sxtinguishers

.in fizzy drinks 

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experiment (atmosphere)

founding out the amount of oxygen in the air:

.in this experiment copper is burning
 as it does it uses the oxygen to form copper oxide

.let the apparatus cool down before taking the reading on the syringe because this will make your results more accurate, as gases expand when they're heated

.the sources of error in this experiment are:
 taking measurements when the gases are still hot
 if not all the copper has reacted, there might be some oxygen left
 you might have the wrong amounts of materials needed
 repitition would make it more reliable 

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experiment (gases and testing preparation)

solubility of oxygen:

.as the temperature of the water increases the solubility of oxygen increases

.solubilty of oxygen in water is measures in g/100g of water

.you would measure the solubility of oxygen

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experiment (gases and testing preparation)

preparing oxygen gas:

.collect 2 spatulas of magnesium (IV) oxide in a flask
 insert a thistle funnel and delivery tube
 fill a boiling tube with water in a trough
 stand it upright (keep the mouth of the tube under the surface of the water)

.the manganese oxidcd the rate of reaction as it acted as a catalyst - speeding up the reaction without being altered itself

the reaction:

hydrogen pyroxide  → water + oxygen
(H
2O2)                        (H2O)   (O2)

.heat was also produced as this reaction is EXOTHERMIC (produces heat)

We proved that oxygen was made by testing it with a glowing split that was re-lit when we put it into the boiling tube because oxygen was present

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metals and non-metals

metals:

.some metals: zinc, tin, nickel, aluminium, copper, lead, iron

.metals are good conducters of heat

.metals are good conducters of electricity

.metals go dull when they are in air
 this is called corrosion
 rusting is a form of corrosion

.metals are shiny, malleable, sonorous, strong and sometimes magnetic 

.most elements are metals

.there are about 70 metallic elements  

.metals are some of the most important materials

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metals and non-metals

non-metals:

.DON'T conduct electricity well

.DON'T conduct heat well

.not shiny, dull, no free flowing electrons

.there are only about 20 non-metallic elements

.very few non-metals are useful materials

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metals and non-metals

testing for metals/non-metals:

.conducting electricity test
 metals conduct electricity well, non-metals don't

.conducting heat test
 metals conduct heat well, non-metals don't

.brittle test
 metals are NOT brittle, non-metals are

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elements

copper:

.conducts electricity well

.used for wires

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elements

carbon:

.barbeque charcoal

.burns well to give lot's of heat

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elements

chlorine:

.kills germs in swimming pools and water supplies

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elements

gold:

.stays shiny

.used for jewellery

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elements

aluminium:

.very light

.used for window frames

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elements

helium:

.very light 

.used in balloons 

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elements

titanium

.very hard

.used for aeroplane parts

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elements

oxygen:

.gas we use in our bodies which is taken in by the lungs

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elements

mercury:

.liquid metal

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experiment (burning magnesium)

does magnesium change when it burns?:
method:

.weigh a crucible and it's lid on a balance
 record it's mass
 add a piece of metal to the crucible and re-weigh
 record the mass
 heat the crucible using a heat flame
 after every minute remove the lid for 10 seconds and then put the lid back on (use tongs and avoid touching the crucible once heated as it will be extremely hot)                  heat for 5 minutes then leave to cool 
 re-weigh the crucible, it's contents and the lid                                                              record the mass
.when the metal was heated it lost (?) 0.2g in mass
reactants                         product
magnesium +oxide →       magnesium oxide
.when the magnesium burns it reacts with the oxygen in the air to form magnesium oxidethe magnesium oxide has a greater mass than the magnesium because the mass of the oxygen has been added to the mass of the magnesium

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experiment (metals and non-metals)

heating metals and non-metals:

                           magnesium                         sulphur

observations        shiny, malleable,                 yellow
before                 solid
heating 

observations        burns -white, bright             melts - becomes a liquid
while                   light produces a                  burns with a blue flame
heating                white powder

observations        the indicator turns                the indicator turns yellow/
with                     blue/purple                         red - acid
indicator              - alkali

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metals and non-metals

metal and non-metal oxides:

.usually metal oxides have a high pH

.usually non- metal oxides have a low pH

.metal oxides are alkali

.non-metal oxides are acid

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experiment (acids and carbonates)

preparing carbon dioxide:

acid + carbonate  → salt + water + carbon dioxide
2HCI + CaC0
3   → CaCI2  + H 20 + C02

.carbon dioxide can be prepared by reacting an acid (in this case hydrochloric acid) with a carbonate (in this case carbonate CaC03)

.carbon and oxygen

.carbon burns producing carbon dioxide

.carbon dioxide is a non-metal oxide

.carbon monoxide is a non-metal oxode produced when carbon burns in a limited supply of oxygen
 this causes the reactants to fizz violently as the carbon dioxide is produced
 carbon dioxide is heavier than air so it will DISPLACE the air inside the gas jar and push it UPWARDS
 to test if the gas produced is C02 we can use LIMEWATER
 when C0is bubbled through limewater a white PRECIPITATE is formed which makes the limewater CLOUDY

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acids and carbonates

what will happen when acids mix with carbonates:

.give off bubbles of gas

.majority turned limewater (used in this experiment) cloudy

.when a metal carbonate reacts with an acid, it fizzes giving off carbon dioxide 

.when a metal carbonate reacts with an acid the products are a salt, carbon dioxide and water

metal carbonate + acid  → salt + carbon dioxide + water

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acids and carbonates

precipitate - a solid formed by the reaction of two solutions

2C02(g) + Ca(OH)(aq) => CaC03 + H2O (l)

.the salt produced depends on the metal carbonate and type of reaction:

.when a metal carbonate reacts with hydrochloric acid the salt produced is metal chloride

.when a metal carbonate reacts with suphuric acid the salt produced is metal sulphate

.when a metal carbonate reacts with nitric acid it produces metal nitrate 

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thermal decomposition

thermal decomposition: a chemical reaction in which heat breaks a compound down in to two or more products

.the more reactive a metal is, the harder it is to decompose it's carbonate by heating

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experiment (thermal decomposition)

.as the copper carbomate is heated, a gas is formed which travels to the limewater and turns it cloudy

.the copper carbonate changes colour from green to black as it is heated

.the thermal decomposition of copper carbonate:

copper carbonate → carbon dioxide + copper oxide
CuCO
3                      → CO2                     + CuO


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experiment (thermal decomposition)

aim: to find out which carbonates break down most easily

apparatus: spatula, stop clock, stand, clamp, boss, carbonates, limewater, measuring cylinder, digital balance

method:

1. measure 10cm³ of limewater with a measuring cylinder 

2. set up apparatus as seen beneath

3. measure 2g of carbonate and put it in boiling tube 1 (check diagram in chem book)

4. heat the carbonate

5. repeat for all carbonates

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thermal decomposition

(decrease, going down, in reactivity)

potassium

sodium

calcium

magnesium

aluminium

manganese

zinc

iron

copper

silver

gold 

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experiment (acid rain)

are all rocks and buildings effected by acid rain?:

method:
1. put on a lab coat and goggles

2. place the specimin of your building material on a watch glass

3. use a pipette and place 1cm³ of acid on to your specimin

4. if your specimin is a carbonate, watch for bubbling

5. for all specimins, watch for a reaction

conclusion:
some of the materials we tested were effected by acid but most weren't
of the materials we tested marble and limestone reacted but brick, granite, slate, sandstone and iron didn't
the marble bubbled and fizzed
the limestone vigorously fizzed and had a strong smell 

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acid rain

.sulphur is a non-metal

.when it reacts with oxygen it forms sulphur oxide (SO2)

sulphur + oxygen → sulphur dioxide

.the acidity is mainly due to dissolved sulphur dioxide and nitrogen dioxide from air pollution

.acids react with all calcium carbonates and therefore damage all limestone/marble buildings

.problems of acid rain:
 erodes stonework
 damages paint on cars
 pollutes lakes and rivers
 damages plants

.the problem of acid rain in britain has been decreased by:
 burning less fossil fuels
 removing sulphur from fossil fuels before they are burned
 removing sulphur dioxide from flue gases

 

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acid rain

type of material     observations when acid added       does acid effect the material

brick                    nothing happened                           no

marble                 bubbling and fizzing                        yes

granite                 nothing happened                           no

slate                    nothing happened                           no

limestone             vigurously fizzed, strong smell         yes

sandstone            nothing happened                           no

iron                      nothing happened                           no

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gases

gases are:

invisible
not solids or liquids
no shape or size
no limit on mass

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gases

helium (He)

.element + molecule

.light, colourless, odourless

.won't burn

.can be turned in to a liquid and used for fridges

.sound has a higher frequency in helium

.makes balloons float

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gases

nitrogen (N2)

.molecule

.no colour, no smell, no taste

.makes up about 4/5's of the air

.put in crisp packets to stop squashing

.put in racing car tyres

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gases

argon (Ar)

.element + molecule

.colourless, odourless

.forms a very small part of the air

.used in light bulbs and radio tubes

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gases

carbon dioxide (CO2

.dense, colourless, odourless

.formed when any fuel containing carbon is burned

.found in air breathed out of animals' lungs

.plants use it in photosynthesis

.used in fizzy drinks/fire extinguishers

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gases

oxygen (O2)

.molecule

.colourless, odourless, tasteless

.animals and plants need it for respiration

.fire needs it to burn

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gases

hydrogen (H2)

.molecule

.colourless, odourless

.almost insoluble in water

.far lighter than air (lightest gas)

.burns readily in air

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molecules etc re-cap

molecule: made up of two or more atoms

compound: made of more than one type of atom/element, joined together by chemical bonds

mixture: a substance composed of 2 (two) or more elements (compounds) that are physically mixed together, but not chemically combined

atom: a single atom

element: pure substance, made of one type of atom

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experiment (hydrogen preparation)

(check diagram in book)

.dilute suphuric acid is added to granulated zinc in a flask via a thiste funnel

.the hydrogen gas is collected by downward displacement of water

zinc  + sulphuric acid => zinc sulphate + hydrogen
Zn(s) + H2SO(aq)        =>ZnSO4(aq)      + H2(g)

.test for hydrogen:
 explodes with a vicious pop in the presence of air (oxygen) when a flame is introduced 

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hydrogen

.when hydrogen burns, water is the only product

H2 + O2 => H2O

.tests for water - H2O

1. water has no colour or smell

2. water puts out a lit splint

3. water or it's vapour will turn cobalt chloride paper from blue to pink

4. water or it's vapour turns anhydrous copper (II) sulphate crystals from white to blue

5. water melts at 0°C and boils at 100°C

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hydrogen

making hydrogen from water:

.water can be split by passing electric current through it in a process called electrolysis

.this is the decomposition of water into oxygen and hydrogen due to an electric current being passedthrough the water

.prouduction of hydrogen from water requires large amounts of energy and is uncompetitive with production from coal or natural gas

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the greenhouse effect and global warming

.gases in the atmosphere such as carbon dioxide, methane, nitrous oxides and CFC's (greenhouse gases) trap the infra red radiation (heat) from the sun that is reflected back from earth

.the greenhouse effect is to do with heat transferred and stored in our atmosphere.
 it is caused by a layar of gases (predominantly carbon dioxide and methane) which prevent heat hitting the earths surface and reflecting back into space, heating our atmosphere

.the ozone layer is a layer of gas in our atmosphere 
 when holes are produced in the ozone layer by man-made gases (e.g. CFC's) it becomes possible for UV light to reach the surface of the planet
 UV light increases the risk of skin cancer

.over the past century there has been a steep increase in temperature - proof for global warming 

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formulae

things to check tohelp you write formula:

1. is the chemical an element or a compound

- iron is an element, so it's symbol is it's formula

- there are 7 exceptions I2, Br2, Cl2, F2, O2, N2, H- these are all DIATOMIC molecules (2 atoms)

2. If the chemical is a compound does the name tell you the formula?

- the name contains mon, di, tri
e.g. carbon MONoxide - CO
      carbon DIoxide- CO2

(check book for diagrams) 

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