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OCR A-Level Chemistry Salters B > Developing Fuels > Flashcards

Flashcards in Developing Fuels Deck (44)
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1

Exothermic reaction

A reaction which gives out energy and heats the surroundings

2

Endothermic reaction

A reaction which takes in energy and cools the surroundings

3

How to calculate enthalpy change

Enthalpy change = Enthalpy of the products - Enthalpy of the reactants

4

What are standard conditions

-298K
-1 atm
-1 mol dm^-3
-Standard states

5

Energy transferred = ?

Specific heat capacity x mass (g) x temperature change

6

Specific heat capacity

The amount of energy needed to raise the temperature of 1 kg of a substance by 1 K

7

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

8

Aromatic and aliphatic compounds

Aromatic compounds - compounds that contain one or more benzene rings

Aliphatic compounds - compounds that do not contain any benzene rings

9

Functional group

Modifiers that are responsible for the characteristic chemical reactions of molecules

10

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

11

Homologous series

A series of compounds in which all members have the same general molecular formula

12

Structural isomers

Molecules with the same molecular formula but a different structural formula

13

Average bond enthalpy

The average quantity of energy needed to break a particular bond

14

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

15

Cracking

Any reaction in which a large molecule is made into smaller molecules

16

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

17

Catalyst poisoning

A substance that stops a catalyst functioning properly

18

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

19

Methane reaction with steam

CH4(g) + H2O(g) --> CO(g) + 3H2(g)

Reaction happens with a solid nickle catalyst

20

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

21

Sigma and Pi bonds

Sigma bonds fore due to the overlap of s-orbitals. Pi bonds form due to the overlap of p-orbitals

22

Carbocation

An ion with a positively charged carbon atom

23

Addition reaction

A reaction where two or more molecules react to form a single larger molecule

24

Hydration reaction

The addition of hydrogen to a molecule in a chemical reaction

25

Polymerisation

Monomers joining together to produce long chain polymers

26

Products of complete combustion

Carbon dioxide and water

27

Products of incomplete combustion

Carbon monoxide, carbon, and water

28

What volume does one mole of gas occupy

24 dm^3

Amount in moles = Volume/24 dm^3

29

Ideal Gas Equation

Pressure (Pa) x Volume (m^3) = Moles x Gas Constant (8.314) x Temperature

PV = nRT

30

Position isomerism

When the functional group or substituted atom is in a different place