661561
| Pregunta | Respuesta |
| two factors that affect the contribution of a greenhouse gas to global warming | 1.atmospheric concentration 2.ability to absorb I.R. radiation |
| two methods developed to achieve carbon capture and storage | 1.storage of carbon dioxide under pressure on the sea bed. 2.reaction of carbon dioxide with metal oxides to form stable carbonate minerals 3.liquefy the carbon dioxide and pump it into old gas wells in the North Sea |
| two ways in which the use of catalysts helps chemical companies to make their processes more sustainable. | 1.catalysts allow for the reaction to proceed in lower temperature which makes it cheaper->les fuel is used up so less pollution 2.catalysts are used but not used up in the reaction 3.different reactants can be used ith better atom economy due to the specific nature of catalysts which increases efficiency |
| two reasons why there is still concern about ozone depletion | ->CFCs are still being used ->takes many years for the ozone to recover |
| why 1-iodopropane is hydrolysed faster than 1-bromopropane | ->C-I bond is longer and weaker than C-Br so is more easily broken so 1-iodopropane is hydrolysed faster |
| two ways in which polymers are procesed usefully rather thsn just dumped in landfill sites | 1.Combuston for energy production 2.separation into type followed by recycling |
| suggest why the average bond enthalpy of a C=C bond is not twice the bond enthalpy of a C-C bond | ->because sigma bonds are stronger than pi bonds |
| problem aused by dispoing of PTFE and PVC in this way? | ->they produce toxic gases |
| describe two way in which chemists can reduce this enviromental damage | 1.developing biodagradable polymers 2.developing methods of storing and recycling |
| homologous series | is a group of organic compounds with the same general formula and te same functionalgroup. |
| fuctional group | is a group of atoms in a compoud that are responsible for the characteristic properties of that compound |
| standard enthalpy change of reactin | ethalpy change tha takes place when the amounts of reactants shown in the equation react under standard conditions |
| standard enthalpy change of foration | enthalpy change when 1mole of a compud is formed under standard conditions |
| standard entalpy change of combustion | enthaly change when 1mole of an elementor compound is burned in excess oxygen under standard conditons |
| the mean(averae)bond enthalpy | is the mean amount of energy required to breack one mole of a particular type of covalent bond in the gaseous state |
| why linear molecules have higher boiling points than branched molecules | the arrangment of linear molecules means there are more areas of surface contact so more intermolecular forces which makaes the bonds harder to breack hence the boiling point is higher |
| exothermic | ... |
| activation energy | is the minimum energy needed on collision for a reaction to take place |
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