Chemistry - AOS 1

q=m*C*ΔT (q in joules=mass grams*SHC*change in temp in degrees C)

Poor insulation, heat lost to surroundings and value measured for ΔT will be lower

How much energy required to change the temp of water in calorimeter by 1 degree C

E=VIt (volts*amps*seconds)

CF=E/ΔT

A substance with stored energy that can be released relatively easily for use as heat or power

A fuel is considered to be non-renewable if it cannot be replenished at the rate at which it is consumed. Fossil fuels such as coal, oil, and natural gas are considered non-renewable

Fossil fuels are produced over millions of years by the breakdown of biomass at high temperatures and pressures underground.

A fuel is considered to be renewable if it can be replenished at the rate at which it is consumed. Biofuels such as biogas, bioethanol and biodiesel are renewable.

Biogas is formed by the anaerobic breakdown of organic waste.

Bioethanol can be produced by the fermentation of starches and sugars

Biodiesel is produced in a reaction between a vegetable oil or animal fat, and a small alcohol molecule such as methanol.

Petrol, natural gas, biogas, and bioethanol undergo combustion in excess oxygen to form CO2 and H2O

Thermal energy creates steam, which turns a turbine. 30-40% efficient

CO, sulfur dioxide, nitrogen oxides, and particulates

Large reserves, relatively high energy contentNon-renewable, high level of emmisions

More efficient than coal, easy to transport, relatively high energy contentNon-renewable, limited reserves, polluting but less than coal and petrol

Renewable, made from waste, reduces waste disposal, low running costsLow energy content, supply of waste raw materials limited

High energy content, ease of transportNon-renewable, polluting but less than coal, limited reserves

Renewable, can be made from waste, CO2 absorbed during photosynthesis, burns smoothly, fewer particulates than petrolLimited supply of raw materials from which to produce it, lower energy than petrol, may require use of farmland otherwise used for food production

Low cost, easily seperated from natural gas, relatively high energy content, fewer particulates than petrolNon-renewable, polluting but less than petrol

Better fuel economy due to higher energy efficiency, and higher energy per litre10-20% less CO2 emissions

Petrodiesel is non-renewablePetrodiesel is seperated from crude oil by fractional distillation.Composed 75% alkanes containing 10-15 carbon atoms, 25% aromatic compounds

1. Biodiesel is renewable2. marginally lower energy content3. higher viscosity4 more likely to need antifreeze additives in cold climates,5. produces CO2 but is consumed in production of tryglycerides used to make the fuel. Fewer particulates. Produces other pollutants. 6. Biodiesel produced from farm crops can add to land degradation and might lead to higher food prices. Biodiesel made from waste products such as used booking oil have a positive impact on the environment1. Petrodiesel is non-renewable2. marginally higher energy content3. lower viscosity4. can be used without additives at lower temps than biodiesel, 5. produces CO2, particulates and other pollutants6. Oil fields prone to spills and damage to local habitats. Oil refineries produce emissions that have a negative impact on local regions.

J=10^-3kJ=10^-6MJ

In the bonds between atoms and molecules

A chemical reaction that releases energy to the surroundings is called an exothermic reaction. A chemical reaction in which energy is absorbed from the surroundings is called an endothermic reaction.

Exothermic

The magnitude of the energy change and whether energy is absorbed (postive value) or released (negative)

Doubles it as twice as many reactants react to produce or absorb twice as much energy.

Because changes of state involve enthalpy changes

The energy that must be absorbed to break the bonds in the reactants so that a chemical reaction can proceed.

Negative

ΔH​c​​ is heat of combustion, and indicates maz amount of energy that can be released when a specified amount of fuel undergoes complete combustions. Common units are kJ/mol, kJ/g and KJ/tonne.

Incomplete combustion occors when a substance undergoes combustion in a limited supply of oxygen.

E=n*ΔH​c​​ (n=number of moles)

Number of moles

4.187 kJ/kg/K

Specific heat capacity of a substance measures the quantity of energy needed to increase the temperature of a specified quantity of that substance by 1 degree C

mass (in grams)

1L=1000mL=1000cm^3

1m^3=1*10^6cm^3=1*10^6mL=1000L

Force per unit area

1 bar = 100 kPa = 1.00*10^5Pa

1 atm = 760 mmHg = 1.013*10^5 Pa = 101.3kPa = 1.013 bar

V∝nV∝1/PV∝T

25C (298K) and 100 kPa

0C (273K) and 100 kPa

n=V/Vm

24.8 L/mol

22.7L/mol

PV=nRt R=8.31J/K/mol

n=m/M

Molar mass of substance