|Release of energy, increases temperature of surroundings.|
|Absorption of energy, decreases temperature of surroundings.|
|energy being transferred in a chemical reaction under specific conditions.|
|If ?H is positive it is a …………..reaction.|
If ?H is negative it is a …………..reaction.
|Positive = endothermic -more energy in products than reactants.|
Negative = exothermic- more energy in reactants than products.
|Define the molar enthalpy of combustion.|
|The molar enthalpy of combustion of a substance is the quantity of heat energy released when 1 mole of a pure element or compound is burnt completely in oxygen under constant pressure.|
|Steps in writing equations for combustion reactions.|
|1. Write reactants and products|
2. Balance Carbon
3. Balance Hydrogen
4. Balance Oxygen
|Define the molar enthalpy of solution.|
|The molar enthalpy of solution of a substance is the quantity of heat energy released or absorbed when 1 mole of the substance dissolves in sufficient water so that further dilution causes no further release or absorption of heat energy.|
|Define the molar enthalpy of neutralisation.|
|The molar enthalpy of neutralisation is the quantity of heat energy released when 1 mole of hydrogen ions is transferred from an acid to a base in an acid-base reaction occurring in aqueous solution.|
|Equation for calculating the ?H?|
|?H = m(water) x ?T(water) x Cp(water)/ (1000 x n)|
|What are the raw materials of fossil fuels?|
|Through what chemical process are fossil fuels produced?|
|What are the three fossil fuels?|
|Crude oil, natural gas, coal|
|What are the advantages and disadvantages of coal as a fuel?|
|A: easily mines with low cost. Large reserves.|
D: production of greenhouse gas, acid rain, non-renewable, hazardous mining, variable composition, harmful products of combustion.
|What are the advantages and disadvantages of crude oil as a fuel?|
|A: large reserves, easily extracted and transported, produces a range of fuels.|
D: non-renewable, variable composition, risky transport(oil spills, flammable), produces harmful gases.
|What are the advantages and disadvantages of natural gas as a fuel?|
|A: easily extracted purified and distributed, combusts cleanly, high energy density.|
D: harmful combustion products, non-renewable, flammable, less common
|What are the raw materials and chemical process that produce ethanol?|
|Sugar, grain crops, Ag waste by fermentation.|
|What are the advantaged and disadvantages of ethanol as a fuel?|
|A: high oxygen – likely to completely combust, only produces CO2 and water, renewable.|
D: poor fuel economy, use of fossil fuels in manufacture, uses up agricultural land, not readily available.
|Name two exothermic reactions.|
|Combustion and respiration|
|Name an exothermic reaction.|
|What are the advantages and disadvantages of biofuel?|
|A: Renewable and biodegradable. Fewer harmful emissions. Improved engine lubrication.|
D:blends can damage engine, decreased fuel economy, can congeal at low temp, expensive, fossil fuels used in manufacture, not widely available, emission contribute to photochemical smog.
|Equation for the complete combustion of fuels.|
C6H12 + 9O2 = 6CO2 + 6H2O
?H = -3616 kJ/mol