1. 01/10/2015 OCR Additional Science Chemical Economics W Richards The Weald School

2. 01/10/2015 Rates of Reaction Hi. I’m Mike Marble. I’m about to have some acid poured onto me. Let’s see what happens… Here comes an acid particle… It missed! Here comes another one. Look at how slow it’s going… No effect! It didn’t have enough energy! Oh no! Here comes another one and it’s got more energy…

3. 01/10/2015 Rates of Reaction View animation Chemical reactions occur when different atoms or molecules _____ with enough energy (the “________ Energy): Basically, the more collisions we get the _______ the reaction goes. The rate at which the reaction happens depends on four things: 1)The _______ of the reactants, 2)Their concentration/pressure 3)Their surface area 4)Whether or not a _______ is used (catalysts are specific to certain reactions) Words – activation, quicker, catalyst, temperature, collide

4. 01/10/2015 Measuring the Rate of Reaction Two common methods:

5. 01/10/2015 Rate of reaction graph Amount of product formed/ reactant used up Time Slower reaction Fast rate of reaction here Slower rate of reaction here due to reactants being used up

6. 01/10/2015 Rate of reaction graph Amount of product formed/ reactant used up Time Q. What if less reactants were used?

7. 01/10/2015 Calculating the Rate of Reaction Amount of product formed/ reactant used up Time Rate of reaction = the gradient of the graph 20cm 3 10s Rate of reaction = 2cm 3 /s

8. 01/10/2015 Atomic mass SYMBOL PROTON NUMBER = number of protons (obviously) RELATIVE ATOMIC MASS, A r (“Mass number”) = number of protons + number of neutrons

9. 01/10/2015 Relative formula mass, M r The relative formula mass of a compound is the relative atomic masses of all the elements in the compound added together. E.g. water H 2 O: Therefore M r for water = 16 + (2x1) = 18 Work out M r for the following compounds: 1)HCl 2)NaOH 3)MgCl 2 4)H 2 SO 4 5)K 2 CO 3 H=1, Cl=35 so M r = 36 Na=23, O=16, H=1 so M r = 40 Mg=24, Cl=35 so M r = 24+(2x35) = 94 H=1, S=32, O=16 so M r = (2x1)+32+(4x16) = 98 K=39, C=12, O=16 so M r = (2x39)+12+(3x16) = 138 Relative atomic mass of O = 16Relative atomic mass of H = 1

10. 01/10/2015 Calculating the mass of a product E.g. what mass of magnesium oxide is produced when 60g of magnesium is burned in air? Step 1: READ the equation: 2Mg + O 2 2MgO IGNORE the oxygen in step 2 – the question doesn’t ask for it Step 3: LEARN and APPLY the following 3 points: 1)48g of Mg makes 80g of MgO 2)1g of Mg makes 80/48 = 1.66g of MgO 3)60g of Mg makes 1.66 x 60 = 100g of MgO Step 2: WORK OUT the relative formula masses (M r ): 2Mg = 2 x 24 = 48 2MgO = 2 x (24+16) = 80

11. 01/10/2015 Work out M r : 2H 2 O = 2 x ((2x1)+16) = 36 2H 2 = 2x2 = 4 1.36g of water produces 4g of hydrogen 2.So 1g of water produces 4/36 = 0.11g of hydrogen 3.6g of water will produce (4/36) x 6 = 0.66g of hydrogen M r : 2Ca = 2x40 = 80 2CaO = 2 x (40+16) = 112 80g produces 112g so 10g produces (112/80) x 10 = 14g of CaO M r : 2Al 2 O 3 = 2x((2x27)+(3x16)) = 204 4Al = 4x27 = 108 204g produces 108g so 100g produces (108/204) x 100 = 52.9g of Al 2 O 3 1)When water is electrolysed it breaks down into hydrogen and oxygen: 2H 2 O 2H 2 + O 2 What mass of hydrogen is produced by the electrolysis of 6g of water? 3) What mass of aluminium is produced from 100g of aluminium oxide? 2Al 2 O 3 4Al + 3O 2 2) What mass of calcium oxide is produced when 10g of calcium burns? 2Ca + O 2 2CaO

12. 01/10/2015 Percentage Yield Percentage yield = actual yield (in g) theoretical yield Example question: Theoretical yield = the amount of product that should be made as calculated from the masses of atoms Actual yield = what was actually produced in a reaction 65g of zinc reacts with 73g of hydrochloric acid and produces 102g of zinc chloride. What is the percentage yield? Zn + 2HCl ZnCl 2 + H 2

13. 01/10/2015 Percentage yield Some example questions: 1)The predicted yield of an experiment to make salt was 10g. If 7g was made what is the percentage yield? 2)Dave is trying to make water. If he predicts to make 15g but only makes 2g what is the percentage yield? 3)Sarah performs an experiment and has a percentage yield of 30%. If she made 50g what was she predicted to make? Percentage yield = Actual yield Predicted yield X 100%

14. 01/10/2015 Batch and Continuous processes In summary: ProcessBatchContinuous What it meansReactants are thrown in, the reaction happens and the batch is removed The reactants are continually fed in and the products are continually removed (e.g. the Haber Process) AdvantagesMakes a wide variety of products on demand Operate all the time and automatically, makes a large amount of product DisadvantagesMore labour intensiveCan only make one product

15. 01/10/2015 Developing new medicines The process: Step 1 - research Step 2 - development Step 3 - legalities Step 5 - marketing Step 4 - manufacture

16. 01/10/2015 Forms of Carbon 1) Diamond – very hard, doesn’t conduct electricity, very high melting point 2) Graphite – soft, does conduct electricity, very high melting point 3) Buckminsterfullerene – 60 carbon atoms arranged in a sphere

17. 01/10/2015 Forms of Carbon Choose a form of carbon and research the following: 1)What properties does this form of carbon have? 2)How are the electrons arranged in this structure? 3)How does the structure of this form affect its properties?

18. 01/10/2015Nanoscience Nanoscience is a new branch of science that refers to structures built from a few hundred atoms and are 1- 100nm big. They show different properties to the same materials in bulk. They also have a large surface area to volume ratio and their properties could lead to new developments in computers, building materials etc. Task: research nanoscience and find two current and/or future applications of this science.

19. 01/10/2015 Using sea water Q. Given all the problems with water shortages, why can’t we just purify sea water and use it for drinking water? Research task: