Chemistry Y11 paper 2

Transcription

1 9-1 GCSE Combined Science Knowledge Organiser Chemistry Y11 paper 2 Topic 6 Rate and extent of chemical changes Pg Topic 7 Organic Chemistry pg Topic 8 Chemical Analysis Pg Topic 9 Chemistry of the atmosphere pg

2 GCSE Chemistry Revision Topic 6 Factors affecting rates of reaction (p100-3) Reactions can go at different rates. The rate of a reaction is how fast the are changed into Reactants Products Examples of slow reactions include Examples of fast reactions include Graphs for the rates of reaction The steeper the line on the graph, the the rate of reaction. Over time the line becomes less steep because Graph 4 shows that the reaction is than the original reaction and that products are made. Factors affecting Rates of Reaction In a nutshell, in order to react, particles must with enough for the reaction to happen. Any change which increases either of these things will increase the rate of reaction. There are FOUR things you can change: Increasing the Temperature increases the rate because it makes the particles move This means they will more frequently and will have more. Increasing Concentration or Pressure increases the rate because there are more in the same volume. This means they will collide more Increasing the Surface Area increases the rate because breaking up a solid increases its to ratio. Because there is more area, there will be collisions Using a Catalyst increases the rate without being, so it is not part of the overall equation. Different reactions need different catalyst. An is an example of a biological catalyst. The Rate of Reaction is worked out by using: Rate = Amount of reactant used/product formed Time taken If the chemical is a gas, measure amount in If the chemical is solid, measure amount in Time is measured in Hence Rate is measured in or

3 GCSE Chemistry Revision Topic 6 Rates: Rates Experiments (p ) Following (and measuring) Chemical reactions 1. Precipitation and Colour Change If the solution is and the 3. The volume of gas given off (e.g Mg in acid) Magnesium and dilute react to produce gas Investigating the effect of using different acid concentrations using Method 1 product is a, we can look at a mark through the solution and time This method is subjective Method Method because 2. Change in Mass (because is given off) Taking measurements at regular intervals means we can The cotton wool here because Investigating the effect of using different acid concentrations using Method 3 Results Conclusion This method is the most accurate because The quicker the reading on the balance drops Conclusion

4 GCSE Chemistry Revision Topic 6: Finding Reaction Rates from Graphs (p107) Calculating the mean reaction rate from a graph Draw a Tangent to find the Reaction Rate at a particular point The mean reaction rate means the average rate for whole reaction to finish. The reaction is finished when the line. You can also find the mean rate between two times. change in Mean rate = change in = - = cm 3 /s Drawing a tangent 1. Put the ruler on the graph at the point you want to know the rate. 2. Adjust the ruler until 3. Draw a line across the ruler to make the. Extend the line right across the graph. 4. Pick two points that are easy to read. change in y Gradient = Find the gradient of this tangent, Answers cm 3 /s (and graph C)

5 No beard GCSE Chemistry Revision Topic 6: Rates Reversible Reactions (p ) There are two types of equilibrium: Static Equilibrium Where NOTHING is actually moving Dynamic Equilibrium Where two things are moving in opposite directions Reversible reactions can be Endothermic and Exothermic If a reversible reaction is Exothermic in one direction, it is in the other direction Endothermic means that heat is transferred the surroundings. Exothermic means that heat is transferred the surroundings. If you heat blue copper sulfate it drives the water off and leaves white copper sulfate. Reversible Reactions will reach an Equilibrium A + B C + D The sign shows that If we start with A and B, they will react together to make C and D. The concentration of A and B will and the concentration of C and D will. Therefore the rate at which A and B react together will get and the rate at which C and D will react together will get. At this point BOTH reactions are still happening, but at the SAME Another example of a Dynamic Equilibrium If the RATE at which water enters the tank is the SAME as the RATE at which the water leaves the tank, the water LEVEL will stay the same. This is the POSITION of EQUILIBRIUM Henry Louis Le Chatelier Inventor of the Principle which bears his name, he had insufficient facial hair to be classed as a proper Chemist, and spent his life being rejected by Chemistry Clubs Le Chatelier s Principle is used to predict what effect on the position of equilibrium will be caused by changing the CONDITIONS. The position will move to try to COUNTERACT the change Changing the Temperature N 2 + 3H 2 2NH 3 Here, the forward reaction is exothermic, so increasing the temp causes the position to move to counteract this and reduce the temp. The position will move in the endothermic temperature. Hence the equilibrium moves to the and the amount of NH 3 in the final reaction mixture Changing the Pressure N 2 + 3H 2 2NH 3 Here there are 4 moles of gas on the left and two on the right. Moving the position of equilibrium to the right will decrease the pressure. Hence, if the pressure is decreased, the equilibrium moves to the and the amount of of NH 3 in the final reaction mixture Changing the Concentration N 2 + 3H 2 2NH 3 If you increase the concentration of N 2 and H 2 the position of equilibrium will move to decrease the concentration of N 2 and H 2 Hence, if the concentration of N 2 and H 2 is increased, the equilibrium moves to the and the amount of of NH 3 in the final reaction mixture

6 Chemistry Topic 7 Organic Chemistry p Hydrocarbons contain only two elements, which are and. The general formula of an alkane is C H Alkanes form a.... series, ie a of compounds that will the same way. Draw the displayed formula Methane Make a spider diagram to summarise how short hydrocarbons are different to long ones: More useful as f.. Lower b p less v., short hydrocarbons. More v. More f Complete combustion happens when Fractional distillation is used to s. hydrocarbon f from the mixture in c.. o... The oil is h.. so that it v..the g.. rise up the c, cooling down as they go. They c back to l. when they reach their b p. fraction use no of carbons Ethane The carbon is o to form c.. d. and the h... is oxidised to form Propane w... CH O 2 CO H 2 O KEY WORDS: tar for road building >40 ASSESSMENT: Butane C 3 H 8 + O 2.. CO H 2 O C 5 H O 2.. CO 2 + H 2 O hydrocarbon alkane homologous series general formula combustion oxidation distillation

7 Chemistry Topic 7 Uses of oil, cracking and alkenes p118 gas used as a Long carbon chains can be broken up by a form of thermal d. called c. p.. for cars Catalytic cracking involves h. the hydrocarbons to f for use in industry v. them, then passing the vapour over the c.. k. for fuel d.. fuel tar for road building Steam cracking involves simply heating to a very h.. t... The point of cracking is to make shorter hydrocarbons out of long ones. This is useful because Feedstock for the petrochemical industry is used to make: p. (plastics and fabrics) s. (for dissolving things) l.. (for making machinery run smoothly) d (for removing grease. To test whether something is an alkane or an alkene you add b. w.. and shake it. If it is an a. then it d the bromine water. If it is an a then the bromine water stays bright o... Cracking always makes a shorter alkane and an alkene. Complete the equations colour code alkanes and alkenes C 10 H 22 C 8 H 18 + C 18 H 38 C 10 H 22 + C 14 H 30 C 9 H 20 + C 12 H 26 C 8 H 18 + C 22 H 46 C 10 H 22 + Alkenes have C=C bonds. For example ethene molecular formula displayed formula C H KEY WORDS: cracking feedstock catalyst thermal decomposition decolourised molecular formula displayed formula ASSESSMENT:

8 GCSE Chemistry Revision Topic 8: Chemical Analysis part 1 (p122-3) The definition of PURE depends on where you are coming from. CHEMISTS EVERYONE ELSE FOUR Tests for Common Gases 1. Chlorine Chlorine damp, turning it white. 4. Carbon Dioxide Pure STUFF melts and boils at SPECIFIC TEMPERATURES. So you can TELL if something is a by measuring the mp or bp and looking it up in a. Impurities the mp and the bp Formulations Formulation is a POSH WORD for RECIPE, except that the recipe is very precise, so that the STUFF has specific properties for a precise job! Formulations are used to make: 2. Oxygen 3. Hydrogen If you hold a splint at the open end of a test tube Oxygen gas will a splint containing Hydrogen gas, you ll get a Could it be true that I hold here, in my mortal hand, a nugget of purest green? Bubbling Carbon Dioxide through an aqueous solution of (known as limewater), causes the solution to turn. The FORMULATION of Coca- Cola has changed over the years, but it is still an INDUSTRIAL SECRET! Originally the formulation contained cocaine (which was derived from the coca leaf) and caffeine (which came from the kola nut), leading to the name Coca-Cola the K was replaced cos it looks better! The Secret Recipe for Coco-Cola s Natural Flavourings Oil Orange 80 ml Oil Lemon 120 ml Oil Nutmeg 40 ml Oil Cinnamon 40 ml Oil Coriander 20 ml Oil Neroli 40 ml Alcohol 2 litres (let stand for 24 hours)

9 Answers 1.D, 2 A, 3 C, GCSE Chemistry Revision Topic 8: Part 2 Paper Chromatography (p124-5) Chromatography uses Two Phases Chromatography is an analytical method used to out the substances in a mixture. Information can be used to the substances. The two phases are: A phase, where the molecules CAN move. It is always a or A phase, where the molecules CAN T move. It can be a or a really thick. Working out what the chemical is You can calculate a number based on the experiment. It is called the for each chemical Measure the distance moved by the solvent (A) Measure the distance moved by the spot (B) The R f value is the ratio of these two values Since (B) must be less than (A), R f values are ALWAYS less than ONE! The further the substance moves through the stationary phase, the the R f value. How it works.. 1. During the experiment the substances in the sample move between the stationary and mobile phases, forming an between them. 2. The Mobile phase moves THROUGH the stationary phase and anything in the mobile phase moves with it. 3.The speed at which a chemical moves depends on the amount of time it spends in the mobile phase. 4. The more time in the mobile phase, the it moves. 5. The substance will separate to form. 6. A substance only forms ONE spot because there is only one substance in it!

10 GCSE Chemistry Revision Topic 9 atmosphere Phase 1 The Earth formed billion years ago. How did the oceans form? Phase 2 Initially the first crust formed, which was covered in, which gave out a lot of gases, and formed the early. What happened to the Carbon Dioxide that dissolved in the oceans? What do the shells of marine animals contain? What types of organisms evolved to extract Carbon Dioxide for photosynthesis? The early atmosphere contained mostly virtually no Volcanic activity also released,, and small amounts of and. KEY WORDS: Algae Oceans Nitrogen Carbon Dioxide Oxygen Atmosphere EXTRA INFORMATION Where can we find evidence for what the old atmosphere was like?

11 GCSE Chemistry Revision Topic 9- atmosphere Carbon compounds can be trapped in fossil fuels and rocks. Explain using simple diagrams how fossil fuels are formed. Phase 3 Green plants and algae producing oxygen Write the photosynthesis equation that shows how green plants and algae produce oxygen. Plants and animals die, and are buried Compression True or false Green plants formed before Algae ( T/ F ) Oxygen allowed more complex life forms to evolve (T / F ) The atmosphere we have today is similar to the atmosphere 200 million years ago ( T / F ) Gases and oil trapped under impermeable rock Fill in and label the pie chart showing the current composition of the atmosphere. Give three facts about Limestone.

12 GCSE Chemistry Revision Topic 9 climate change and greenhouse effect p Name these molecules CO 2 (g) CH 4 (g) H 2 O (g) Use the diagram to complete this radiation Short wavelength Comes from the Absorbed by atmosphere? These are. gases : they make the atmosphere The greenhouse effect is useful because Long wavelength Another name for long wave radiation is.. radiation: this.. the surface of the earth. This is called the effect. Explain the effect of these examples of human activity Explain these effects of climate change KEY WORDS: Absorb Wavelength Thermal radiation Re-radiate Greenhouse effect Climate change MORE KEY WORDS: Peer-review Reliability Variables Bias Computer model

13 GCSE Chemistry Revision Topic 9 carbon footprint and pollution A carbon footprint is a measure of Carbon footprints are difficult to measure because We could reduce carbon footprints by: Using. You would need to consider the following factors to make a rough calculation of the carbon footprint of a service, p or e : New technologies are not yet well developed instead of Use more e processes to conserve e and reduce w. Governments could put c on emissions. Companies pay for a l for e up to that limit. Making reductions to carbon footprints is difficult because.. Capture c d before it is released into the atmosphere. It would be stored in Governments could tax companies or individuals based on Examples include KEY WORDS: Carbon footprint Greenhouse gas Renewable energy Emissions Carbon capture Life cycle Individuals could reduce their carbon footprint by: 1) 2) 3)

14 GCSE Chemistry Revision Topic 9 carbon footprint and pollution Combustion What is combustion? Particulates Particulates in the air cause lots of problems. If Inhaled: Sulfur Dioxide and Oxides of Nitrogen Sulfur dioxide is released during the combustion of... What is a hydrocarbon? Nitrogen oxides are created from Complete combustion is when The products of complete combustion are Incomplete combustion is when The products of complete combustion are For the environment: Carbon monoxide Why is carbon monoxide so dangerous? How does it stop your blood from doing it s job? What are the effects of carbon monoxide poisoning on humans? When these gases mix with in clouds they form dilute or dilute. This falls as. Acid rain is bad because it You can test for sulfur impurities in a fuel by bubbling combustion gases through solution. If SO 2 is present the indicator will turn in colour indicating an ph. KEY WORDS: complete combustion incomplete combustion global dimming acid rain hydrocarbon particulates sulfur dioxide oxides of nitrogen Why is carbon monoxide so hard to detect? Complete the diagram above showing formation of acid rain by filling in the blank boxes