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C3 Spaced Learning. Measuring Reaction Rate Either measure: How fast the reactant is used up Or How fast a product is formed Units of rate depend on what.

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Presentation on theme: "C3 Spaced Learning. Measuring Reaction Rate Either measure: How fast the reactant is used up Or How fast a product is formed Units of rate depend on what."— Presentation transcript:

1 C3 Spaced Learning

2 Measuring Reaction Rate Either measure: How fast the reactant is used up Or How fast a product is formed Units of rate depend on what you measured g/s or g/min cm 3 /s or cm 3 /min The steeper the line, the faster the reaction. Horizontal = reaction has stopped. The limiting reactant is the one that is all used up in the reaction. If you double the amount of limiting reactant, you double the number of particles available to make the product so, you double the amount of product. To find the rate of the reaction from the graph, 1. Find the gradient of the line. 2. Use the axis labels to work out the units. C3

3 Temperature, concentration and pressure (spot the difference – one answer = many questions!) When you increase the concentration, there are more particles in the same volume of liquid, so the particles collide more often, and so the reaction is faster. When you increase the pressure, there are more particles in the same volume of gas, so the particles collide more often, and so the reaction is faster. When you increase the temperature, the particles move faster, so the particles collide more often, And so the reaction is faster. When you increase the temperature The particles have more energy So a higher proportion of collisions are successful And so the reaction is faster. Reaction rate depends on How often the reactant particles collide How much energy is transferred during the collision (whether is it successful or not.) The red line shows the most concentrated, highest pressure or highest temperature reaction.

4 Surface area and catalysts Possible catalystAppearance at the start Volume of gas produced in 60 seconds. (cm 3 ) Appearance at the end None-45- CopperOrange/brown80Orange/brown Copper sulfateBlue98orange/brown Magnesium sulfateWhite46white A catalyst is a substance which speeds up a chemical reaction and is unchanged at the end of the reaction. Only a small amount of catalyst is needed. Catalysts are specific to a reaction which means that a catalyst that works for one reaction might not work for another reaction. Explosions are very fast reactions that produce lots of gas. Fine combustible powders are dangerous in factories because they can cause an explosion. When you cut a solid up into smaller pieces, you increase the surface area, so the particles collide more often, and so the reaction is faster. The red line is powdered reactant because it is steeper = faster reaction. Copper is the catalyst because it speeds up the reaction and remains the same at the end.

5 Reacting Masses Find the relative formula mass of the following. The relative atomic mass, Ar of C=12, O=16, Mg=24, H=1 and Zn=65 CO 2 = = 44 MgCO 3 = = 84 Mg(OH) 2 = 2x(16+1) +24 = 2 x = 58 Mass is conserved in a chemical reaction. The particles that are there at the start are there at the end – just rearranged. You cannot make new particles. CaCO 3  CaO + CO 2 Show, by calculation, that mass is conserved in this reaction. And calculate the mass of CaO produced if you start with 5g of CaCO 3 The relative atomic mass, A r of Ca = 40, C=12, O=16. Finding the relative formula masses of the reactants and products: CaCO 3 = = 100 CaO = = 56 CO 2 = = 44 So products should = reactants: 100 = /100 = ?/56 ? = (5 x 56)/100 ? = 2.8g When you see these in a question, start by doing the adding up the formula sum.

6 % yield and atom economy Percentage yield 100% = no product lost 0% = no product made Atom economy 100% = all the atoms in the reactants are in the desired product High atom economy = greener. You must know the formula: % yield = actual yield x 100 predicted yield little number ÷ big number x 100 In industry As high a % yield as possible Reduces the reactants wasted Reduces cost In industry As high an atom economy as possible Reduces the production of unwanted products Makes the process more sustainable You must know the other formula: Atom economy = relative formula mass of desired products x 100 sum of the relative formula masses of all products

7 Energy Exothermic = energy given out = temperature increases = bond making Endothermic = energy taken in = temperature decreases = bond breaking In a reaction bonds are broken and made. If a reaction is exothermic, the energy needed to break the bonds is less than the energy which is given out when the new bonds are made. To compare the energy transferred per gram of different fuels. Use a spirit burner Heat a known mass of water in a copper calorimeter Measure the mass of fuel burnt Measure the temperature change Making it fair and valid Use the same volume of water, same temperature change, same height above the flame, stir to heat evenly. Energy transferred (J) = mass of the water x specific heat capacity x change in temperature The exam paper won’t say this part, but you must remember to use the water mass, not the fuel mass. Energy per gram = energy transferred (J) _ mass of fuel burnt (g) You need to be able to rearrange this to find the mass or the change in temperature.

8 BatchContinuous Cost of equipmentLowHigh Rate of productionLowHigh Shut down and start up times Short – easy to doTake a long time, hard to do. WorkforceMany people – need to be trained. Few people, no special training Ease of automationDifficultEasy Type of productHigh quality chemicals, seasonal Chemicals needed in large quantities Extracting chemicals from plants: Crush Boil to dissolve in a solvent Chromatography to separate The purer the chemical, the closer the melting/boiling point will be to the pure substance. Why it is expensive to make, test and develop new pharmaceutical drugs. Research Testing – to make sure they are not toxic and will do as they should. Labour costs Energy costs Raw materials Time taken for development Marketing

9 Allotropes Diamond, graphite and fullerenes are allotropes of carbon because they are all made of carbon atoms, but the atoms are arranged differently which gives them different properties Diamond Jewellery – shiny and attractive Cutting tools – hard Does not conduct electricity All the electrons are involved in C-C bonds Is hard and has a high melting point Because the covalent bonds are all strong So they take lots of energy to break. Graphite Pencil leads – slips easily off the pencil, black, Lubricants – slippery High melting point – because the covalent bonds are strong and take lots of energy to break. Slippery – the layers slide over each other easily Conducts electricity – because only three of the carbons four electrons are involved in covalent bonds so there are free electrons which can move and conduct. Diamond and graphite both have giant molecular structures because all of the atoms are covalently bonded together. Other giant molecular structures will have similar properties. Nanotubes are used in new drug delivery systems because the drug can be placed inside the nanotube cage to stop it damaging other parts of the body while it is delivered to a tumour. Nanotubes can be used as catalysts as they have a huge surface area for the reactants to collide with.

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11 Measuring Reaction Rate Either measure: Or Units of rate depend on what you measured How do you know which is fastest? The limiting reactant is….. If you double the amount of limiting reactant………. To find the rate of the reaction from the graph, 1… 2… One way we could collect the gas. Another way we could collect the gas Another way we could measure the reaction rate.

12 Measuring Reaction Rate Either measure: How fast the reactant is used up Or How fast a product is formed Units of rate depend on what you measured g/s or g/min cm 3 /s or cm 3 /min The steeper the line, the faster the reaction. Horizontal = reaction has stopped. The limiting reactant is the one that is all used up in the reaction. If you double the amount of limiting reactant, you double the number of particles available to make the product so, you double the amount of product. To find the rate of the reaction from the graph, 1. Find the gradient of the line. 2. Use the axis labels to work out the units.

13 Temperature, concentration and pressure (spot the difference – one answer = many questions!) When you increase the concentration, When you increase the pressure, When you increase the temperature, When you increase the temperature Reaction rate depends on The red line shows

14 Temperature, concentration and pressure (spot the difference – one answer = many questions!) When you increase the concentration, there are more particles in the same volume of liquid, so the particles collide more often, and so the reaction is faster. When you increase the pressure, there are more particles in the same volume of gas, so the particles collide more often, and so the reaction is faster. When you increase the temperature, the particles move faster, so the particles collide more often, And so the reaction is faster. When you increase the temperature The particles have more energy So a higher proportion of collisions are successful And so the reaction is faster. Reaction rate depends on How often the reactant particles collide How much energy is transferred during the collision (whether is it successful or not.) The red line shows the most concentrated, highest pressure or highest temperature reaction.

15 Surface area and catalysts Possible catalystAppearance at the start Volume of gas produced in 60 seconds. (cm 3 ) Appearance at the end None-45- CopperOrange/brown80Orange/brown Copper sulfateBlue98orange/brown Magnesium sulfateWhite46white A catalyst is a substance Only Catalysts are specific to a reaction which means Explosions are Fine powders are dangerous because When you cut a solid up into smaller pieces, The red line is Explain which substance is the catalyst…

16 Surface area and catalysts Possible catalystAppearance at the start Volume of gas produced in 60 seconds. (cm 3 ) Appearance at the end None-45- CopperOrange/brown80Orange/brown Copper sulfateBlue98orange/brown Magnesium sulfateWhite46white A catalyst is a substance which speeds up a chemical reaction and is unchanged at the end of the reaction. Only a small amount of catalyst is needed. Catalysts are specific to a reaction which means that a catalyst that works for one reaction might not work for another reaction. Explosions are very fast reactions that produce lots of gas. Fine combustible powders are dangerous in factories because they can cause an explosion. When you cut a solid up into smaller pieces, you increase the surface area, so the particles collide more often, and so the reaction is faster. The red line is powdered reactant because it is steeper = faster reaction. Copper is the catalyst because it speeds up the reaction and remains the same at the end.

17 Reacting Masses Find the relative formula mass of the following. The relative atomic mass, Ar of C=12, O=16, Mg=24, H=1 and Zn=65 CO 2 MgCO 3 Mg(OH) 2 Mass is conserved in a chemical reaction because CaCO 3  CaO + CO 2 Show, by calculation, that mass is conserved in this reaction. And calculate the mass of CaO produced if you start with 5g of CaCO 3 The relative atomic mass, A r of Ca = 40, C=12, O=16. When you see these in a question, start by doing the adding up the formula sum.

18 Reacting Masses Find the relative formula mass of the following. The relative atomic mass, Ar of C=12, O=16, Mg=24, H=1 and Zn=65 CO 2 = = 44 MgCO 3 = = 84 Mg(OH) 2 = 2x(16+1) +24 = 2 x = 58 Mass is conserved in a chemical reaction. The particles that are there at the start are there at the end – just rearranged. You cannot make new particles. CaCO 3  CaO + CO 2 Show, by calculation, that mass is conserved in this reaction. And calculate the mass of CaO produced if you start with 5g of CaCO 3 The relative atomic mass, A r of Ca = 40, C=12, O=16. Finding the relative formula masses of the reactants and products: CaCO 3 = = 100 CaO = = 56 CO 2 = = 44 So products should = reactants: 100 = /100 = ?/56 ? = (5 x 56)/100 ? = 2.8g When you see these in a question, start by doing the adding up the formula sum.

19 % yield and atom economy Percentage yield Atom economy 100% = High = You must know the formula: In industry As high a % yield as possible because In industry As high an atom economy as possible You must know the other formula:

20 % yield and atom economy Percentage yield 100% = no product lost 0% = no product made Atom economy 100% = all the atoms in the reactants are in the desired product High atom economy = greener. You must know the formula: % yield = actual yield x 100 predicted yield little number ÷ big number x 100 In industry As high a % yield as possible Reduces the reactants wasted Reduces cost In industry As high an atom economy as possible Reduces the production of unwanted products Makes the process more sustainable You must know the other formula: Atom economy = relative formula mass of desired products x 100 sum of the relative formula masses of all products

21 Energy Exothermic = Endothermic = Explain why a reaction is exothermic overall. To compare the energy transferred per gram of different fuels. Making it fair and valid Energy transferred (J) = mass of the water x specific heat capacity x change in temperature The exam paper won’t say this part, but you must remember to use the water mass, not the fuel mass. Energy per gram = energy transferred (J) _ mass of fuel burnt (g) You need to be able to rearrange this to find the mass or the change in temperature.

22 Energy Exothermic = energy given out = temperature increases = bond making Endothermic = energy taken in = temperature decreases = bond breaking In a reaction bonds are broken and made. If a reaction is exothermic, the energy needed to break the bonds is less than the energy which is given out when the new bonds are made. To compare the energy transferred per gram of different fuels. Use a spirit burner Heat a known mass of water in a copper calorimeter Measure the mass of fuel burnt Measure the temperature change Making it fair and valid Use the same volume of water, same temperature change, same height above the flame, stir to heat evenly. Energy transferred (J) = mass of the water x specific heat capacity x change in temperature The exam paper won’t say this part, but you must remember to use the water mass, not the fuel mass. Energy per gram = energy transferred (J) _ mass of fuel burnt (g) You need to be able to rearrange this to find the mass or the change in temperature.

23 BatchContinuous Cost of equipment Rate of production Shut down and start up times Workforce Ease of automation Type of product Extracting chemicals from plants: The purer the chemical, … Why it is expensive to make, test and develop new pharmaceutical drugs..

24 BatchContinuous Cost of equipmentLowHigh Rate of productionLowHigh Shut down and start up times Short – easy to doTake a long time, hard to do. WorkforceMany people – need to be trained. Few people, no special training Ease of automationDifficultEasy Type of productHigh quality chemicals, seasonal Chemicals needed in large quantities Extracting chemicals from plants: Crush Boil to dissolve in a solvent Chromatography to separate The purer the chemical, the closer the melting/boiling point will be to the pure substance. Why it is expensive to make, test and develop new pharmaceutical drugs. Research Testing – to make sure they are not toxic and will do as they should. Labour costs Energy costs Raw materials Time taken for development Marketing

25 Allotropes Diamond, graphite and fullerenes are allotropes of carbon because Diamond Jewellery – utting tools Does not conduct electricity Because Is hard and has a high melting point because Graphite Pencil leads – Lubricants – High melting point – because Slippery – Conducts electricity – Diamond and graphite both have giant molecular structures because Nanotubes are used in new drug delivery systems because Nanotubes can be used as catalysts as

26 Allotropes Diamond, graphite and fullerenes are allotropes of carbon because they are all made of carbon atoms, but the atoms are arranged differently which gives them different properties Diamond Jewellery – shiny and attractive Cutting tools – hard Does not conduct electricity All the electrons are involved in C-C bonds Is hard and has a high melting point Because the covalent bonds are all strong So they take lots of energy to break. Graphite Pencil leads – slips easily off the pencil, black, Lubricants – slippery High melting point – because the covalent bonds are strong and take lots of energy to break. Slippery – the layers slide over each other easily Conducts electricity – because only three of the carbons four electrons are involved in covalent bonds so there are free electrons which can move and conduct. Diamond and graphite both have giant molecular structures because all of the atoms are covalently bonded together. Other giant molecular structures will have similar properties. Nanotubes are used in new drug delivery systems because the drug can be placed inside the nanotube cage to stop it damaging other parts of the body while it is delivered to a tumour. Nanotubes can be used as catalysts as they have a huge surface area for the reactants to collide with.


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