Using and Controlling Reactions – Chapter 3 Flashcard

Exothermic Reactions
Release of energy, increases temperature of surroundings.
Endothermic Reactions
Absorption of energy, decreases temperature of surroundings.
Define enthalpy
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?
plant and animal remains
Through what chemical process are fossil fuels produced?
Anaerobic breakdown
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.
Photosynthesis.
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

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