Chemistry Unit 1

electrolysis Breaking stuff * down ( * compounds) using electricity

Where electrolysis happens Battery – provides electricity Electrode (+) Electrode (-) Electrolyte – liquid with compounds (needing breaking) Cell

Compounds the examiners want you to ELECTROLYSIZE HCl 2.NaCl 3.H 2 O

Electrolysis of liquid NaCl Na + Cl - Na + Cl - Na + Cl - Na + Cl - Chlorine : Collected as gas!

Electrolysis of liquid HCl H+H+ Cl - H+H+ H+H+ H+H+ CHLORINE : Collected as gas! HYDROGEN : Collected as gas!

Electrolysis of WATER H+H+ O 2- H+H+ H+H+ H+H+ OXYGEN : Collected as gas! HYDROGEN : Collected as gas!

CHLORINE It is a TOXIC gas USES: 1.Treat water supplies; kills bacteria 2.Needed to make BLEACH 3.Make polymer.... POLY(CHLORETHENE) a.k.a PVC

CHEMICAL TESTS

EXTRACTION of METALS

POTASSIUM SODIUM CALCIUM MAGNESIUM ALUMINIUM ZINC IRON TIN LEAD COPPER SILVER GOLD

POTASSIUM OXIDE SODIUM OXIDE CALCIUM OXIDE MAGNESIUM OXIDE ALUMINIUM OXIDE ZINC OXIDE IRON OXIDE TIN OXIDE LEAD OXIDE COPPER SILVER GOLD Metals are found as ORES! Extracted using ELECTROLYSIS Extracted using CARBON

EXTRACTION METHOD 1. CARBON + HEAT ZINC OXIDE + CARBON  ZINC + CARBON DIOXIDE IRON OXIDE + CARBON  IRON+ CARBON DIOXIDE TIN OXIDE + CARBON  TIN + CARBON DIOXIDE LEAD OXIDE + CARBON  LEAD + CARBON DIOXIDE

ELECTOLYSIS – Aluminium Oxide (BAUXITE) Al 3- O 2-

PROPERTIES of METALS

1.STRONG 2.CONDUCTS ELECTRICITY 3.MANDIBLE

ALUMINIUM LOW DENSITY CORROSION RESISTANT

COPPER STRONG HIGH Mpt GOOD CONDUCTOR OF ELECTRICITY

GOLD SHINY EASY TO SHAPE AMAZING ELECTRICAL CONDUCTOR

CORROSION Basically.... It’s when OXYGEN and reacts with metal. OXIDATION! Why do metals higher up the reactivity series get more CORROSIVE?

Rusting.... (corrosion of IRON) Iron + oxygen  Iron Oxide (rust)

IRON Iron Ore Heat Impure (cast) iron

Impure iron = BRITTLE Purification PURE iron = TOO SOFT!

PURE iron + (carbon)  STEEL (alloy)

Alloys

Alloys.... Smart alloys e.g. Nitinol – nickel and titanium

NOTE TO SELF... ONLY PLAY TO THE CHEMISTS IF THEY HAVE BEEN BEHAVING WELL OR SKIP, WITHOUT GIVING THEM A BREAK.

THE ATMOSPHERE STARTER: Our current atmosphere consists of the following gases..... (list them!)

Carbon dioxide Water vapour NO OXYGEN 4.5 BILLION YEARS AGO..

AS TIME WENT ON Water vapour cooled = OCEANS 2. Carbon dioxide DISSOLVED in oceans Green plants EVOLVED; released OXYGEN

Changes in the atmosphere notes… The Earth is surrounded by a mixture of gases called the a____________. Gases given out by volcanic activity formed the early atmosphere  mostly c_______ d_______ with little or no o_______. Overtime the proportion of CO 2 decreased as it was locked up in rocks and fossil fuels, absorbed by plants during p_____________ and dissolved in the oceans. The proportion of __________ increased as plants photosynthesised. The main gases in today’s atmosphere are nitrogen (____%), oxygen (___%), argon (___%) and carbon dioxide (___%). The proportion of carbon dioxide is now i_________ due to the burning of f_______ f________.

Changes in the atmosphere notes… The Earth is surrounded by a mixture of gases called the atmosphere. Gases given out by volcanic activity formed the early atmosphere  mostly carbon dioxide with little or no oxygen. Overtime the proportion of CO 2 decreased as it was locked up in rocks and fossil fuels, absorbed by plants during photosynthesis and dissolved in the oceans. The proportion of oxygen increased as plants photosynthesised. The main gases in today’s atmosphere are nitrogen (78%), oxygen (21%), argon (~1%) and carbon dioxide (~0.03%). The proportion of carbon dioxide is now increasing due to the burning of fossil fuels.

HAZARD SYMBOLS : DO YOU KNOW WHAT THEY MEAN ? Match the symbol to its correct meaning : Radioactive Toxic Harmful/irritant Dangerous for the Environment Oxidising Corrosive Highly Flammable Explosive CORROSIVE TOXIC FLAMMABLE IRRITANT HARMFUL OXIDISING DANGEROUS FOR THE ENVIRONMENT EXPLOSIVE RADIOACTIVE

WHAT HAPPENS WHEN... ACID + ALKALI  SALT + WATER NEUTRALISATION!!

NEUTRALISING ACIDS – KEY POINTS: Only METAL OXIDES, HYDROXIDES and CARBONATES can be used to neutralise acids General reaction for these are: Acid + metal OXIDE  SALT + WATER Acid + metal HYDROXIDE  SALT + WATER ACID + metal CARBONATE  SALT + WATER + CARBON-DIOXIDE

The salt that is formed depends on the acid in the reaction: Sulphuric acid  Sulphate salts Nitric acid  Nitrate salts Hydrochloric acid  Chloride salts

Sulfuric acid + Copper Oxide  Copper sulfate + water Nitric acid + Sodium hydroxide  Sodium nitrate + water Hydrochloric acid + Copper carbonate  Copper chloride + water + Carbon dioxide

QUESTION : 1.Why do you see bubbles when you react copper carbonate with acid but not when you use copper oxide? 2.What is the test for Carbon dioxide gas?

CLEARING UP AN ACID SPILL..... WHAT’S THAT THEY ARE POURING ONTO THE ACID?

Ca(OH) 2 CaO CaCO 3 Calcium Oxide Calcium Carbonate Calcium Hydroxide TOPIC: Limestone and Stuff...

CHALK LIMESTONE

USES of LIMESTONE: 1.For buildings 2.To make cement 3.The cement can make CONCRETE 4.Make glass

CaO QUICKLIME = CaO

CaO WATER EXPLOSIVE REACTION

REMINDER – how are these compounds made? Calcium heat calcium carbon Carbonate  oxide + dioxide calcium + water calcium oxide  hydroxide QUICKLIMESLAKED LIME VERY SLOWLY

USES OF LIMESTONE PRODUCTS... 1.Neutralising acidic soils 2.To remove acidic gases from coal powered stations

ACID RAIN

ACIDIC SOIL  Ca(OH) 2 NEUTRALISED SOIL

2. Reducing emissions Power stations burn COAL (Coal contains SULPHUR), so when it burns it gives out SULPHUR DIOXIDE SULPHUR DIOXIDE

SOLUTION SULPHUR DIOXIDE Ca(OH) 2

C H E M I S T R Y mark

CRUDE OIL A hydro-carbon is.... (2 marks) A compound made from hydrogen and carbon atoms ONLY

Process of separating hydrocarbons based on different boiling points is called... FRACTIONAL DISTILLATION

As you go up the fractional distillation column the... Size of the hydrocarbon chains gets So, the boiling point gets.... The flammability.... The liquid gets (viscosity).....

As you go up the fractional distillation column the... Size of the hydrocarbon chains gets......smaller So, the boiling point gets.... lower The flammability.... increases The liquid gets LESS VISCOUS (runny) Properties of crude oil in FD column

BURNING FUELS 1.Complete combustion 2.Incomplete combustion Most alkanes are used as fuels to produce useful forms of energy.

COMPLETE combustion – burning fuel with PLENTY of OXYGEN!

Fuels When completely burned, alkanes form carbon dioxide and water. Hydrocarbon + oxygen  carbon dioxide + water

Complete the equation... Methane + Oxygen  Water + Carbon dioxide CH 4 + O 2  H 2 O + CO 2

INCOMPLETE combustion – burning fuel with NOT ENOUGH OXYGEN!

HYDROCARBON + OXYGEN  CARBON + CARBON DIOXIDE + CARBON MONOXIDE +WATER

Complete the equation... Methane + Oxygen  CARBON + CARBON DIOXIDE + CARBON MONOXIDE +WATER Methane +

CARBON MONOXIDE Why is it bad for us? 1.Toxic gas; it is colourless, odourless 2. Carbon monoxide combines with haemoglobin; forms carboxy-haemoglobin 3. Prevents blood carrying oxygen  4. No oxygen reaches cells / no respiration / death

TEST FOR ALKANES AND ALKENES 1. ADD BROMINE WATER (brown/orange solution).... RESULT  ALKANE (SINGLE BOND) - stays brown RESULT  ALKENE (DOUBLE BOND) - DECOLOURISED, goes from brown to COLOURLESS

CLEAR SOLUTIONS

An alkene may be distinguished from an alkane by shaking the hydrocarbon with b_______w______. Bromine water is b_______ or o______, and will lose its colour when it reacts with the d_______b____ of an alkene. Bromine water will stay b_______ with an alkane because an alkane has no d_______ b________. Bromine adds across the double bond of an alkene to form a c__________ dibromo alkane. This is an example of an addition reaction. An addition reaction occurs when two or more reactants join together to form a single product. HOW TO DISTINGUISH BETWEEN ALKANES AND ALKENES

An alkene may be distinguished from an alkane by shaking the hydrocarbon with bromine water. Bromine water is brown or orange, and will lose its colour when it reacts with the double bond of an alkene. Bromine water will stay brown with an alkane because an alkane has no double bonds. Bromine adds across the double bond of an alkene to form a colourless dibromo alkane. This is an example of an addition reaction. An addition reaction occurs when two or more reactants join together to form a single product. HOW TO DISTINGUISH BETWEEN ALKANES AND ALKENES

What is it? Breaking long chain hydrocarbons into smaller ones Why do it? High demand for shorter chain molecules Products: SHORTER chain ALKANE and an ALKENE CRACKING

1.The long hydrocarbons are heated up 2.so they turn into a gas (VAPOURISED) 3.They are passed over a catalyst. 4.THERMAL DECOMPOSITION takes place (They are broken down by the heat!) CRACKING ence/aqa_pre_2011/oils/polymersrev1.shtml

ence/aqa_pre_2011/oils/polymersrev5.shtml

What do we do with the left over alkenes? POLYMERISATION Joining lots of monomers (small alkenes) to make very long chains, called polymers dition.html ence/aqa_pre_2011/oils/polymersrev5.shtml

MONOMER POLYMER

1. Global Warming Main cause: Carbon dioxide from burning fossil fuels causing a “greenhouse” effect ENVIRONMENTAL ISSUES...

2. Acid rain Main cause: 1.sulphur compounds in fuels burning to form sulphur dioxide 2.nitrogen dioxide from car exhausts.... dissolves in rainwater to produce an acidic solution ENVIRONMENTAL ISSUES...

Making biofuel.. e.g. Ethanol Made by fermenting SUGAR CANE and SUGAR BEET Burns to give carbon dioxide and water Cars adapted to use mixture of 10% ethanol and 90% petrol

PROS: It is renewable; petrol is finite Production of BIOFUEL uses CO 2 from atmosphere (carbon neutral) Environmentally friendly Increased labour – more jobs, tackle poverty CONS: Need lots of land to grow fuel Losing land to grow food Biodiversity and loss of habitats Not 100% efficient BIOFUELS