Developing Fuels Flashcards
Exothermic reaction
A reaction which gives out energy and heats the surroundings
Endothermic reaction
A reaction which takes in energy and cools the surroundings
How to calculate enthalpy change
Enthalpy change = Enthalpy of the products - Enthalpy of the reactants
What are standard conditions
- 298K
- 1 atm
- 1 mol dm^-3
- Standard states
Energy transferred = ?
Specific heat capacity x mass (g) x temperature change
Specific heat capacity
The amount of energy needed to raise the temperature of 1 kg of a substance by 1 K
Hess’s law
As long as the starting a finishing points are the same, the enthalpy will always be the same, irrespective of how you get from the start to the finish
Aromatic and aliphatic compounds
Aromatic compounds - compounds that contain one or more benzene rings
Aliphatic compounds - compounds that do not contain any benzene rings
Functional group
Modifiers that are responsible for the characteristic chemical reactions of molecules
Saturated and unsaturated hydrocarbons
Saturated hydrocarbon - a molecule with no carbon-carbon double or triple bonds
Unsaturated hydrocarbon - a molecule with carbon-carbon double or triple bond
Homologous series
A series of compounds in which all members have the same general molecular formula
Structural isomers
Molecules with the same molecular formula but a different structural formula
Average bond enthalpy
The average quantity of energy needed to break a particular bond
Breaking and making bonds, exothermic and endothermic
Breaking bonds is an endothermic process as energy is needed to break the bond. Making bonds in an exothermic process
Cracking
Any reaction in which a large molecule is made into smaller molecules
Heterogeneous and homogeneous catalysis
Heterogeneous catalysis - when the catalyst and the reactants are in different physical states
Homogeneous catalysis - when the catalyst and the reactants are in the same physical states
Catalyst poisoning
A substance that stops a catalyst functioning properly
How does heterogeneous catalysis work
1) Reactants are adsorbed onto the surface of the catalyst
2) Bonds between the reactants break
3) New bonds form to create the products
4) The products diffuse away from the surface of the catalyst
Methane reaction with steam
CH4(g) + H2O(g) –> CO(g) + 3H2(g)
Reaction happens with a solid nickle catalyst
Electrophile
A positive ion or molecule with a which is attracted to a negatively charged region and react by accepting a lone pair of electrons to form a covalent bond
Sigma and Pi bonds
Sigma bonds fore due to the overlap of s-orbitals. Pi bonds form due to the overlap of p-orbitals
Carbocation
An ion with a positively charged carbon atom
Addition reaction
A reaction where two or more molecules react to form a single larger molecule
Hydration reaction
The addition of hydrogen to a molecule in a chemical reaction
