2789011
Descrição
FlashCards por Clelia Serra, atualizado more than 1 year ago
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Criado por Clelia Serra
mais de 9 anos atrás
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| Questão | Responda |
| If an accident occurred during chlorine manufacture, people dealing with the incident would wear breathing masks. Explain why. (2) | Chlorine is a volatile gas Causes respiratory problems |
| Explain in terms of intermolecular bonds, why chlorine is a gas at room temperature and pressure, but bromine is a liquid under the same conditions. Should talk about how intermolecular bonds aries (5) | 1. instantaneous dipole - induced dipole 2. electron movements in the molecules create an uneven distribution of charge. 3. a dipole is induced in a neighbouring molecule leading to attraction. 4. Intermolecular bonds are stronger in bromine 5. Bromine has more electrons 6. More energy, higher temperature to break intermolecular bonds. |
| What is meant by dynamic equilibrium (2) | Rate of forward reaction = rate of backwards reaction Concentrations of reactants and products remain constant. In a closed system |
| The student wanted to dry liquid 1-chlorobutane. Name a drying agent to use | Anhydrous sodium sulfate |
| Name another gas, not CO2, which is present in vehicle exhaust fumes which is a pollutant. Explain why this causes a pollutant effect. (2) | NO/NO2/SO3 - causes acid rain Unburnt hydrocarbons - causes photochemical smog CO2 - causes greenhouse effect CO - cause toxic effects on humans |
| Suggest two ways of reducing the amount of CO2 in the atmosphere other than storing under the ocean (2) | Burn less fossil fuel Named alternative power source (wind/solar power) Less deforestation - more photosynthesis React CO2 with lime Disposing it in an old mine |
| CO2 is a greenhouse gas. Explain how increased concentrations of CO2 in the troposphere could be linked to global warming, saying where the energy comes from originally. (6) | 1. UV from the sun is absorbed by the earth 2. Earth radiates IR 3. CO2 absorbs IR 3. Which causes bonds to vibrate more 4. More CO2 means more radiation is absorbed 5. This energy is transferred to KE this increases atmospheric temperature. |
| poly(ethene) can be converted into 1-phenylethanol. Suggest reagents and conditions that can be used to achieve this | Steam Phosphoric acid catalyst High temp and pressure (60 atm, 300 degrees) |
| Name the type of bond breaking process that occurs to form hydroxyl radicals from water molecules | Homolytic fission |
| Carbon dioxide is a gas room temperature. Silicon dioxide is a solid at room temp. Explain this difference in terms of bonding and structure (3) | SiO2: giant covalent network, whole structure is held together by covalent bonds. CO2 simple molecular. Weaker intermolecular bonds in CO2, less energy needed to separate molecules. Bonds in SiO2 are stronger. |
| Explain the source of IR radiation absorbed by carbon dioxide and the possible link between increased concentrations of CO2 in the troposphere and global warming (6) | 1. Sun emits UV 2. Earth absorbs some of the energy from the sun. 3. Earth re-emits IR 4. CO2 absorbs IR radiation 5. Making bonds vibrate more. 6. Turned into kinetic energy that raises the temperature; by transferring it to thermal energy. 7. Some CO2 molecules radiate IR which warms up the earth. 8. More CO2 molecules means more radiation absorbed |
| Bromomethane and chloromethane are both present in the atmosphere. Explain how chloromethane causes ozone depletion in the stratosphere and suggest why bromomethane has a lower ozone depleting potential than chloromethane. | 1. Choloromethane is not broken down in the troposhere 2. But is broken down in the stratosphere 3. High energy UV 4. Breaks down chloromethane producing chlorine atoms (radicals) 5. The products catalyse ozone depletion 6. C-Br bond is weaker than C-Cl 7. So this can be broken down in the troposphere before reaching the stratosphere. |
| Poly(but-2-ene) can be used to make pipes for water supplies. Suggest two properties of poly(but-2-ene) that make them them suitable for this use | Low flexibility/ does not react with water/ high tensile strength/impermeable/insoluble/ resistant to chemical attack |
| Propan-1-ol has a higher boiling point than propene, explain this in terms of intermolecular bonding (4) | !. Intermolecular bond in propene is instantaneous dipole - induced dipole 2. Hydrogen bonds in propanol are stronger than those in propene 3. intermolecular bonds must be broken for the liquid to boil. 4. More energy needed to break them (as they are stronger) |
| Student carried out the reaction of propene with hydrogen at room temperature and pressure. What catalyst would be required under these conditions. (1) | platinum |
| Iodine can be obtained by burning seaweed, the intermolecular bond between iodine molecules is instantaneous-induced dipole. Explain how this type of bond forms (3) | Electron movements In molecules create an uneven distribution of charge, leading to a temporary dipole The temporary dipole in one molecule induces a dipole in a neighbouring molecule, then attracts it. |
| Suggest why chlorine atoms are more readily reduced than iodine atoms (2) | Cl atom is smaller, it has fewer occupied electron shells, the outer electron shell is closer to the nucleus. 5p rather than 3p So extra electron gained is more strongly attracted by the nucleus. Extra electron has less shielding from nuclear attraction. |
| The OH group in an alcohol can be oxidised by heating under relux with appropriate reagents. Give the reagents that would be needed for the reaction to occur (2) | Acidified potassium dichromate (acidified using sulfuric acid) |
| Describe and explain how the rate of reaction varies under different temperature conditions (5) | 1. Rate is greater when the temperature is higher. 2. At higher temperatures, particles have more energy, so move faster 3. More particle collisions 4. Per unit time 5. More collisions have total energy of at least the activation energy, more successful collisions |
| Explain why a reaction is faster in the presence of a catalyst | Provide an alternative pathway for the reaction with a lower activation energy. |
| Explain how the presence of ozone in the stratosphere benefits us (3) | 1. Ozone stops UV 2. UV of high energy 3. Which could otherwise cause skin cancer, damage DNA, damage eyes. |
| What are the disadvantages of having a build-up of tropospheric ozone | Causes photochemical smog/breathing problems/lung damage/s toxic |
| Describe how you would carry out the heating under reflux in a lab | Boil a liquid in a container attached to a vertical upright condenser |
| Suggest two advantages for heating under reflux (2) | Increases rate of reaction Allows boiling for a long time Stops loss of volatiles Stops liquid catching fire |
| bromobutane was contaminated with another organic liquid. Name the process you would use to seperate these two liquids | Distillation |
| Name a source of propene used in industrial process | crude oil/dehydration of propan-1-ol |
| In a reaction how can the OH- ion be a nucleophile? | It is a negative ion with a lone pair of electron and able to form a dative covalent bond. |
| Suggest a property of expanded poly(phenylethene) other than insolubility which makes it suitable for building houses | Good thermal insulator Low density |
| Explain the meaning of a thermoplastic | Softens when heated |
| Explain why the use of finely divided powder increases the reaction time | More surface area of catalyst, do more collisions per unit time Or provides more surface onto which reactants are adsorbed |
| Poly(ethanol) forms hydrogen bonds between chains. Poly(phenylethene) forms id-id bonds between its chains. - Explain how hydrogen and id-id bonds are formed -Explain why poly(ethenol) is slightly soluble in water, where as poly(phenylethene) isn't (7) | Hydrogen bonds: lone pair on the O, O is small and electronegative. Attracted to hydrogen with partial positive charge Id-Id: Electrons movements in the molecules create an uneven distribution of charge. A dipole is induced in a neighbouring molecule. Poly(ethenol) can for H-bond with water, Poly(phenylethene) cannot |
| The first ionisation enthalpy for potassium is less than for sodium, explain why (2) | Outermost electrons of K are further away from the nucleus, there is more shielding than in Na. Attraction from the nucleus is weaker, less energy is needed to remove an electron |
| Describe the structure and bonding of diamond | Giant network With every C bonded to 4 other C's Each one is tetrahedrally bonded Covalent bonds. |
| Describe the theoretcal work and research that led to the discovery of ozone depletion in the stratophere, and how the evidence was overlooked (3) | Discovery that Cl radical can damage ozone layer SPECTROSCOPIC measurements showed ozone levels depleted, they were much lower than expected. Results were overlooked, thought to be anomalous as they were so low |
| Explain how an increase in the concentration of a greenhouse gas leads to an enhanced greenhouse effect | Greenhouse gas absorbs IR from earth More greenhouse gas means more IR is absorbed |
| Describe the evidence for the relationship between the increased concentration of greenhouse gases and global warming (1) | There is a relationship between models of gas and models of temperature |
| Explain why adding chlorine to water can stop the spread of cholera | Chlorine kills of destroys bacteria because it has anti bacterial properties |
| Suggest two reasons why it may be preferable to use calcium chlorate rather than chlorine for treating drinking water (2) | Calcium chlorate is easy to handle/transport Calcium chlorate is safer, less hazardous to handle. Chlorine has an unpleasant smell Chlorine forms HCl Calcium chlorate is more soluble |
| Give one use for chlorine other than water treatment | Bleach, making PVC, making solvents, disinfectant, making HCl, extraction of bromine. |
| Methanal can be made from methanol in a lab, give the reagents and conditions required for the reaction (3) | Potassium dichromate, acidified with sulfuric acid Distill |
| Describe and explain: - Why the presence of ozone in the stratosphere is important to humans - The natural processes by which ozone is formed in the stratosphere. | 1. It absorbs UV 2. Of high energy 3. Otherwise radiation can cause skin cancer/ damage eyes 4.Oxygen or water molecules are spilt to form radicals 5. UV radiation causes formation of oxygen radicals 6. The O atoms react with O2 forming ozone. |
| Name the type of intermolecular bond present between molecules of water. Explain how these intermolecular. (3) | 1. Hydrogen bonding between water molecules 2. Lone pair on oxygen atom - oxygen is small and electronegative. 3. Bonds to hydrogen with a partial positive charge. O-H bond polarised |
| Alcohol reacts with hydrogen by an addition reaction. Give the conditions that are required for this reaction (2) | Either: platinum catalyst r.t.p or Nickel catalyst high temp and pressure |
| Explain what is meant by the fingerprint region in an infrared spectrum and explain the significance of the fingerprint region (2) | Region below 1500cm-1 Unique part of the spectrum for the molecules Can be used to identify the molecules by comparison with known values. |
| Methanol can be converted to chloromethane. Give the reagent and conditions required. (2) | Hydrogen chloride/ HCl High temperature |
| Describe how halogenalkanes deplete ozzone and give the evidence for the ozone depletion (3) | 1. halogenoalkanes break down in the presence of UV and give chlorine/ bromine radicals 2. The radicals catalyse the breakdown of ozone. 3. Low ozone concentrations were found above the Antarctic |
| Is the molecules hydrogen sulfide polar? (2) | 1. The H-S bonds are slightly polar because they have different electronegativities. 2. The molecule is polar because the charges do not balance out, it has a positive and a negative side. |
| Suggest two changes that a chemical company could make to its processes to achieve a reduction in the rate of increase in the rate of increase of CO2 levels (2) | 1. Burn a fuel from a plant source 2. Use a alternative source; solar energy/ wind turbine. 3. Improve the efficiency of the process or use a catalyst so less energy is needed |
| Explain how bonds between atoms vibrating more result in warming the atmosphere | 1. Vibrational energy becomes kinetic energy 2. KE results in increased temperature Or 1. The molecules re-emit some of the absorbed IR 2. In all directions |
| Suggest why the balance between CO2 (g) in the troposphere and CO2 (aq) in the oceans cannot be regarded as a true dynamic equilibrium (1) | 1. System is not closed 2. CO2 moves away from the surface |
| Explain, in terms of reactivity of HCFC's in the statosphere, why scientists think HFC's are a good long-term solution as a replacement for CFC's | F radicals not formed in stratosphere as HFCs are not broken down. 2. Because of the stronger C-F bond, this needs more energy to break, UV energy is not a high enough frequency |
| State one advantage and one disadvantage of using HFC's in place of CFC's | 1. same essential properties to the CFC they are to replace 2. Expensive, also a greenhouse gas |
| Compounds; A (tertiary alcohol), B (primary alcohol) are heated under reflux in separate containers with acidified potassium dichromate (vI) solution. Describe the colour change, if any, in each case and explain your answer in terms of alcohol groups in compounds A and B | For compound A: Reaction mixture stays the same colour Tertiary alcohol group is not oxidised, does not react with dichromate. For compound B: Reaction mixture changes from orange to green. Primary alcohol group oxidised to form aldehyde or carboxylic acid. |
| Explain why CFC's are not broken down in the troposhphere and how CFC's contribute to the breakdown of ozone in the stratosphere (5) | 1. bond too strong to be broken in the troposphere. The high energy radiation required is not present in the troposphere 2. In the stratosphere UV breaks bonds, causes photo dissociation 3. To form chlorine radicals 4. Radicals catalyse the breakdown of ozone |
| Describe an explain the effect of an increase in pressure on the rate of reaction (3) | 1. Reaction rate increases 2. Particles are closer together, the concentration increases per unit volume. 3. so collide more frequently per unit time |
| Use ideas about intermolecular bonding to explain bromomethane has a higher boiling point than chloromethane (2) | IMB in bromomethane are stronger More energy needed to break the IMB in bromomethane Because bromomethane has a more electrons |
| Give the reagents and conditions for the reaction of an alkene with hydrogen (2) | Nickel High temp and pressure Or Platinum room temperature |
| Propene reacts with water forming propan-1-ol. Propan-1-ol has a higher boiling point than propene Explain this difference i boiling points in terms of intermolecular bonding | 1. Propene forms id-id bonds 2. propan-1-ol forms hydrogen bonds 3. IMB must be broken for the liquid to boil 4. IMB in propanol are stronger than those in propene, more energy is required to break the bonds. |
| A student wanted to test whether a solution contained Chloride ions. What reagent would they need to use? What would be the result if there was chloride ions present? | Silver nitrate White percipitate - silver chloride |
| What's the strongest type of bond that can form between propanone and ethanol | Hydrogen bond |
| Explain how an increase in the concentration of a greenhouse gas leads to an enhanced greenhouse effect (2) | Greenhouse gas absorbs IR from earth More IR absorbed |
| Describe one natural process that causes ozone to be broken down in the stratosphere (2) | Molecules split by UV To form O and O2 |
| Describe one natural process that caused ozone to be formed from O2 in the stratosphere (3) | 1. Oxygen molecules are split 2. By UV radiation 3. The O atoms react with O2, forming ozone |
| Explain why CO2 molecules absorb only certain frequencies of IR | CO2 absorbs infrared radiation of specific frequencies corresponding to transitions between vibrational energy levels. (Vibrational energy is quantised.) The specific frequencies absorbed make the molecules vibrate in particular ways. The vibrational energy increases |
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