P4 – Radiation for Life

P4 – Radiation for Life • Sparks – electrostatics, moving electrons • Uses of electrostatics – paint sprayer, dust precipitator • Safe electricals – wiring a plug, fuses • Ultrasound – body scans • Treatment – Gamma radiation, X-Rays • What is radioactivity – Half-life, alpha decay, beta decay • Use of radioisotopes – uses of alpha radiation, beta radiation, tracers • Fission – Nuclear power stations

Sparks Electrons move from place to place and create charged objects. • The key point here is that electrons are negative so: • anything that is negative has gained electrons • anything that is positive has lost electrons

Electrostatics Electrons move from place to place and create charged objects. • Paint is charged and spreads out (even spray). • Object to be painted has opposite charge. • Paint gets everywhere (into the shadows). None is wasted. Even coat.

Electrostatics

Safe Electricals Voltage = Current x Resistance Current = Voltage ÷ Resistance Resistance = Voltage ÷ Current

Safe Electricals The live wire carries a high voltage into and around the house. The neutral wire completes the circuit. The earth wire is the safety wire. It stops a person receiving an electric shock if they touch the live metal case of a faulty appliance. A fuse stops too large a current into the circuit. Circuit breakers are re-settable fuses. NOTE: Some plugs don’t need an Earth wire (DOUBLE INSULATED)

Ultrasound Doesn’t harm living cells. Can be used to see soft tissue. • Non-harmful soundwaves. Multiple uses: • Body scans • Breaking up kidney stones • Cleaning delicate equipment

What is Radioactivity? 100% The Half-Life is the time taken for the activity of a radioactive compound to decay to half its original value. 50% 25% Time 2nd half life 5600 years 11200 years 1st half life

What is Radioactivity? Question : An isotope’s half-life is 50 years. If you start with 100 kilograms of it how much is left after 200 years? The Half-Life is the time taken for the activity of a radioactive compound to decay to half its original value.

Uses of Radioisotopes? ALPHA The alpha particles pass between the two charged metal plates, causing air particles to ionise (split into positive and negative ions). The ions are attracted to the oppositely charged metal plates causing a current to flow.

Uses of Radioisotopes? ALPHA When smoke enters between the plates, some of the alpha particles are absorbed causing less ionisation to take place. This means a smaller than normal current flows so the alarm sounds.

Beta detector Paper Rollers Beta emitter Uses of Radioisotopes? BETA

Treatment GAMMA

Treatment X Rays Beam of electrons aimed at a tungsten metal target produces X-Rays

More neutrons Neutron Unstable nucleus Uranium nucleus Fission New nuclei (e.g. barium and krypton)

C4 – Chemical Economics • Acids and Bases – neutralisation, pH, naming • Reacting Masses – Relative atomic mass, % Yield • Fertilisers and crop yield – Making fertilisers • The Haber Process – Ammonia, costs • Detergents – Hydrophobic, hydrophillic, dry cleaning • Batch or continuous – Making chemicals, medicines • Nanochemistry – Forms of carbon • How pure is our water? – Precipitation reactions

Nanochemistry Diamond • Hard • High melting point • Multiple 3-D covalent bonds (very strong structure). • No free electrons • Doesn’t conduct electricity • Shiny 

Nanochemistry Graphite • High melting point • Multiple 2-D covalent bonds. Layers can slide. • Lots of free electrons • Does conduct electricity • Dull - Black

Nanochemistry Buckminsterfullerene • Black solid • Red in petrol • Used to cage other molecules (for drug delivery) • Can be joined to make nanotubes which are used as catalysts

Fertilisers and crop yield Ammonium nitrate is a very important fertiliser. It is made by reacting ammonia with nitric acid. Ammonia + Nitric Acid → Ammonium Nitrate NH3 + HNO3→ NH4NO3 (NH4OH+ HNO3→ NH4NO3 + H2O) You can be asked about other bases and acids reacting together too...

Fertilisers and crop yield Acid + base → Salt + water Acid + oxide → Salt + water Acid + hydroxide → Salt + water Acid + Carbonate → Salt + water + carbon dioxide Can you see they all make a salt and water but only the carbonate makes something extra and that is carbon dioxide gas. The clue is usually in the name of the chemical as it is a carbonate.

Fertilisers and crop yield • Sulfuric acid + sodium hydroxide → Sodium sulfate + water • Hydrochloric acid + copper oxide → Copper chloride + water • Hydrochloric acid + sodium hydroxide → Sodium chloride + water • Sulfuric acid + calcium carbonate → Calcium sulfate + water + carbon dioxide • Nitric acid + potassium hydroxide → Potassium nitrate + water • Nitric acid + ammonia → Ammonium nitrate • Sulfuric acid + sodium carbonate → Sodium sulfate + water + carbon dioxide

Reacting masses Back to ammonium nitrate... NH4NO3 3 Elements: Nitrogen – N Hydrogen – H Oxygen - O 9 Atoms: N H H H H N O O O

Reacting masses Relative formula mass NH4NO3 Calculating Relative Formula Mass 14 + 1 + 1 + 1 + 1 + 14 + 16 + 16 +16 = 80

Reacting masses Percentage of Nitrogen in a compound... NH4NO3 Relative Formula Mass = 80 There are 2 Nitrogens in the compound, mass = 14 + 14 = 28 % Nitrogen = mass of nitrogen ÷ total mass of the compound % Nitrogen = 28 ÷ 80 = 35 %

Reacting masses What about ammonium sulfate? (NH4)2SO4 Calculating Relative Formula Mass 14 + 1 + 1 + 1 + 1 + 14 + 1 + 1 + 1 + 1 +32 + 16 + 16 + 16 + 16 = 132

Reacting masses What about ammonium sulfate? NH4NH4SO4 Calculating Relative Formula Mass 14 + 1 + 1 + 1 + 1 + 14 + 1 + 1 + 1 + 1 +32 + 16 + 16 + 16 + 16 = 132

Reacting masses What about ammonium sulfate? NH4NH4SO4 4 Elements: Nitrogen – N Hydrogen – H Oxygen – O Sulfur - S 15 Atoms: N H H H H N H H H H S O O O O

Reacting masses Percentage of Nitrogen in a compound... (NH4)2SO4 Relative Formula Mass = 132 There are 2 Nitrogens in the compound, mass = 14 + 14 = 28 % Nitrogen = mass of nitrogen ÷ total mass of the compound % Nitrogen = 32 ÷ 132 = 21.2 %

Reacting masses You must be able to balance equations. For example, this one  K2CO3 + HCl → KCl + CO2 + H2O

Reacting masses You must be able to balance equations. For example, this one  K2CO3 + HCl → KCl + CO2 + H2O K 2 1 C 1 1 O 3 3 H 1 2 Cl 1 1

Reacting masses You must be able to balance equations. For example, this one  2 2 K2CO3 + HCl → KCl + CO2 + H2O  K 2 2 1  C 1 1 O  3 3  H 2 1 2 2  Cl 1 1 2

1) Inorganic fertilisers used on fields are washed into the lake 3) This growth causes overcrowding and many plants die due to lack of enough light or food 2) The fertiliser causes increased growth in water plants Fertilisers and crop Yield Yet another example of pollution, eutrophication is when lakes become stagnant due to careless use of fertiliser. There are six steps:

4) Microorganisms and bacteria increase in number due to the extra dead material 6) The lack of oxygen causes the death of fish and other aquatic animals 5) These microorganisms use up the oxygen in the lake during respiration Fertilisers and crop Yield Can’t…breathe…

How pure is our water? We can check water to see if it has got any ions in it by adding different chemicals and watching the changes.

How pure is our water? Water purification: Sedimentation – large particles fall to the bottom. Filtration – small particles filtered out. Chlorination – chlorine added to kill microbes

Fritz Haber, 1868-1934 Nitrogen Mixture of NH3, H2 and N2. This is cooled causing NH3 to liquefy. Hydrogen Recycled H2 and N2 The Haber Process Guten Tag. My name is Fritz Haber and I won the Nobel Prize for chemistry. I am going to tell you how to use a reversible reaction to produce ammonia, a very important chemical. This is called the Haber Process. Nitrogen + hydrogen Ammonia N2 + 3H2 2NH3 To produce ammonia from nitrogen and hydrogen you have to use three conditions: • High pressure • 450O C • Iron catalyst

Batch or Continuous Recall that ammonia is made all the time in a continuous process. Describe that speciality chemicals such as medicines and pharmaceutical drugs are often made on demand in a batch process. Describe how chemicals are extracted from plant sources: crushing; dissolving in suitable solvent; chromatography. • Explain how economic considerations determine the development of new drugs in relation to: • research and development time and associated labour costs; • time required to meet legal requirements including timescale for testing and human trials; • anticipated demand for new product; • length of pay back time for initial investment

B4 – It’s a green world This topic looks at: Plant cells Photosynthesis Minerals Energy flow The carbon cycle The nitrogen cycle

CO2 in air The Carbon Cycle 2. Plants release CO2 through respiration 6. These microbes also release CO2 through respiration 1. CO2 is taken in by plants for photosynthesis and turned into carbohydrates 4. Animals release CO2 through respiration 5. Animals (and plants) die and their remains are fed on by microbes 3. The carbon taken in by plants is then eaten by animals

Photosynthesis

How are plants adapted for photosynthesis? • Epidermis is thin • Palisade cells have a large number of chloroplasts • Air spaces allow gases to diffuse • Large surface area of mesophyll cells therefore large amounts of gases.

The 3 main nutrients… • Nitrates: • Used to make proteins • Lack of it leads to a small plant, yellow leaves • Phosphates: • Used to provide phosphorus to help photosynthesis and respiration • Lack of it leads to small roots and purple leaves • Potassium: • Helps the enzymes that are needed for photosynthesis • Lack of it leads to yellow leaves with dead bits

Nitrates in the soil Waste and dead animals Plants Animals The Nitrogen Cycle 4. Nitrifying bacteria convert ammonium compounds into NITRATES 1. Plants absorb nitrogen in the form of NITRATES 3. Microbes break down waste products and dead animals and plants to form AMMONIUM COMPOUNDS 2. Plants are then eaten by animals – the nitrogen becomes PROTEIN

P4 – Radiation for Life