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Flashcards in Fuels and Heats of reaction Deck (122)
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1

Hydrocarbon

A compound that contains only carbon and hydrogen

2

Saturated compound

a compound in which there are only single bonds between the atoms in the molecule

3

Unsaturated compound

One which contains at least one double or triple bonds netweem the atoms in the molecule

4

Structural isomers

Compounds with the same molecular formula but different structural formulae

5

Aliphatic (compound)

An organic compound that consists of straight (open) chains of carbon atoms and closed chain compounds with similar properties

6

Aromatic (compound)

An organic compound that contains a benzene ring structure in their molecules

7

Octane Number

Octane number of a fuel is a measure of the tendency of the fuel to resist knocking

8

Catalytic cracking

The breaking down of long chain hydro-carbon molecules into short chain molecules by heat and catalysts

9

Auto-ignition

Premature ignition (explosion) of the petrol-air mixture before normal ignition of the mixture by a spark takes place

10

Alkanes

These compounds are a family of hydrocarbons in which all atoms are linked by single bonds (saturated compounds)

11

Alkanes - formula

Cₙ H₂ₙ₊₂

12

Order

Meth
Eth
Prop
But
Pent
Hex
Hept
Oct
Non
Dec

13

Alkane structual and condensed formulas

on hardback

14

Alkenes - formula

Cₙ H₂ₙ

15

Alkenes

1. A homologous series of aliphatic hydrocarbons
2.Lowest member of the series is ethene (2 carbon atoms)
3.Each alkene molecule contains a carbon-carbon double bond
4. Unsaturated compounds

16

Alkenes - methene

No methene due to double bonds

17

Alkynes endings

ends in -yne

18

Alkynes

Contain a carbon-carbon triple bond
Highly unsatured

19

Alkynes formula

Cₙ H₂ₙ₋₂

20

Ethyne

Name - Ethyne
Formula - C₂ H₂
Structural formula: H - C = C - H

Ethyne is the first of the series as you must have a carbon-carbon triple bond. (You need at least 2 carbons)

21

Endothermic reaction

Energy + reactants --> products

22

Activation energy

Activation energy is the maximum point on the reaction graph

23

Example of exothermic reaction and endothermic reaction

Exothermic reaction: Hydrochloric acid + magnesium

Endothermic reaction: water + ammonium nitrate

24

Bomb calorimeter
-use
-method

Used to find accurate values for heats of combustion

-Sample is ignited using electrically heated wire
-Excess oxygen ensures complete combustion of sample
-Heat produced by rapid + complete combustion of the sample heats, water + temperature is recorded
-Apparatus is well insulated to prevent heat loss
-Amount of heat used to start burning can be calculated and removed

25

Bond energy

-Average C-H bond energy in methane: 412 kJ mol⁻¹ ie. E(C-H) = 412 kJ mol⁻¹
-Energy of a particular bond can vary
-It is unusual to quote the average bond energies

26

Natural gas

-A colourless, odourless mixture of gases made up mostly of methane (CH₄). Other gases that can form part of natural gas include small amounts of ethane (C₂ H₆), propane (C₃ H₈), and butane (C₄ H₁₀)
-Methane burns relatively cleanly to produce heat energy + by-products of water and carbon dioxide

27

Why is natural gas useful?

-high kg calorific value
-Plentiful
-Easily distributed

28

Why mercaptans are added to natural gas

Due to natural gas being highly inflammable + explosive, mercaptans are added so it can be detected

29

Fractional distillation

A large-scale, continuous process which separates crude oil into a number of useful mixtures called fractions
eg. refinery gas is a fraction that can be used as a domestic gas

30

Octane number

Measure of the tendency of the fuel to resist knocking
eg. 2, 2, 4 - trimethlypentane is assigned an octane number of 100
heptane is assigned an octane number of 0