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15 Cards in this Set
- Front
- Back
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How does adding a catalyst increase rate of reaction? |
- Catalyst provide alternative pathway for the reaction with lower activation enthalpy - More particles will now exceed activation enthalpy - More successful collisions per unit time = higher (faster) rate |
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Define Dynamic equilibrium |
- The rate of the forward reactions and reverse reactions are equal in a closed system - The concentration of a reactants and products no longer change |
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What affect does increasing pressure has on the equilibrium position? |
Increasing the pressure pushes the equilibrium position to the side with fewer moles of gas which is the left, hence less product is made |
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What affect does rising temperature has on the equilibrium position |
- Rising temperature pushes the equilibrium position in the endothermic direction ( the reverse reaction is endothermic ) which is the left. less product is made |
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The best condition for making x is very high pressure, suggest why only medium pressure is used in reality? |
- Thick walled apparatus to cope with pressure very costly - Large energy costs in creating/keeping high pressure using heavy duty pumps |
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Describe the ways to reduce CO2 levels |
- Burn less fossil fuels and use non carbon based alternatives such as geothermal or tidal - Plant more tress to increase photosynthesis - Pumping it under pressure to the deep ocean floor - Pumping it under pressure into disused oil/gas wells |
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Why is carbon capture and storage not widely used? |
- Apparatus and energy costs of pumping co2 at pressure to bottom of deep sea makes it very expensive - concerns that CO2 may harm marine life in deep oceans by increasing acidity of water |
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What industrial process produce carbon dioxide? |
- Refining oil - Generating electricity - Making iron/steel - fermentation |
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Explain in terms of intermolecular bonds why bromine has higher b.p. than chlorine |
- Non-polar molecules have instantaneous dipole-induced dipole intermolecular bonds - Random movement of electrons in molecules creates uneven distribution of charge. - This induces a dipole in a neighbouring molecule leading to an attraction - Molecules with more electrons (Br2) will form stronger intermolecular bonds - more energy will be needed to overcome/break the stronger intermolecular bonds so b.p. is higher |
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What is E/Z isomerism? |
- the c=c double bound prevents rotation - there must be two different groups on each carbon of the carbon-carbon double bond |
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What is a radical? |
Particles( species) with an unpaired electron |
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Why is the molecule CF3Cl polar? |
- C-Cl and C-F bonds have different polarities - The dipoles/charges do not cancel out or centre of positive of positive and negative charges don't coincide - Or there is a greater (partial ) negative charge on the F side of the molecule |
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Explain the shape of the SO2 molecule and give the bond angle |
- There are 3 regions electron density around the central atom S - Regions of electron density repel as far part as possible to minimise repulsion - the shape is bent and bond angle is 120 |
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What is meant by heating under reflux? |
- Boiling a liquid reaction mixture with a a vertical condenser to prevent products and reactants from boiling away |
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What is meant by the term homogeneous catalyst? |
- Catalyst provides alternative pathway for reaction with lower activation enthalpy - Is chemically unchanged at the end of the reaction - Homogeneous means catalyst is in same state as reactants |
