L1 hydrocarbons

Question 1

what are hydrocarbons?

Answer 1

simplest organic compounds that contains only hydrogen and carbon

Question 2

organic compounds are made by?

Answer 2

living things

Question 3

what was daltons atomic theory?

Answer 3

that organic compounds cannot be synthesized because of vitalism

Question 4

who disproved vitalism and was the first scientist to produce organic compound by synthesis?

Answer 4

Friedrich Wöhler

Question 5

what is the name of the first organic compound produced by Wöhler?

Answer 5

urea

Question 6

what are organic compounds?

Answer 6

all carbon containing compounds but with three exceptions

Question 7

what are the three exceptions of organinc compounds?

Answer 7

1- carbon oxide: carbon + oxygen
CO , CO2
2- carbides: carbon + metal
SiC2 , CaC2
3- carbonates: compounds composed of CO₃²⁻
Na₂CO₃

Question 8

why carbon has the ability to form many organic compounds?
3 reasons

Answer 8

1) carbon has 4 valence electrons thus can form 4 covalent bonds
“electron configuration: 1s^2 2s^2 2p^2”
2) carbon atoms are bonded to hydrogen atoms or atoms of other elements near carbon on periodic table especially nitrogen, oxygen, phosphorus, sulfur, halogens
3) carbon atoms also bond to other carbon atoms and forms long chains forming straight and branched chains, ring and cagelike structures

Question 9

how many bonds can carbon forms?

Answer 9

3 bonds single, double and triple bonds

Question 10

what are the four ways to represent organic compounds?

Answer 10

1) molecular formula - no info on the geometry
2) strutural formula - general arrangement of atoms
3) ball-stick model - geometry of molecule clearly
4) space-filling model - more realistic pic

Question 11

what does saturated hydrocarbons mean?

Answer 11

hydrocarbons that has at least one single bond

Question 12

what does unsaturated hydrocarbons mean?

Answer 12

hydrocarbons that has at least double or triple bonds

Question 13

what is the experiment that classified hydrocarbons?

Answer 13

• hydrocarbons that reacts with bromine –> unsaturated
• hydrocarbons that does not react with bromine –> saturated

Question 14

what do we call hydrocarbons that are obtained from fossil fuels?

Answer 14

petroleum but also natural gas forms at the same time which contains primarily of methane

Question 15

what is fractional distillation?

Answer 15

a process in which they separate crude oil (petroleum) by boiling it and collecting components as they condense at different temperatures

Question 16

in a fractional tower which area are large molecules (large mass) and small molecules (small mass) located?

Answer 16

large molecules at the bottom where there is high boiling point
small molecules at the top where there is low boiling point

Question 17

what does cracking means?

Answer 17

The process in which heavier fractions are converted to gasoline by breaking their large molecules into smaller molecules

Question 18

cracking is done in which conditions?

Answer 18

1- absence of oxygen
2- presence of catalyst

Question 19

why gasoline is modified and substances are added to it?

Answer 19

• to improve its performance in automobile engines
• to reduce pollution from car exhaust

Question 20

why ignition must start at the right moment and burn evenly?

Answer 20

because if it ignites too early or too late it wastes energy, fuel efficiency will drop, and the engine will wear out permanently

Question 21

factors of octane number?

Answer 21

• piston pressure on the air fuel mixture
• altitude at which the car is driven

Question 22

what does pinging and rattling noise called and it caused by what?

Answer 22

its called knocking and it caused by the early ignition from straight chain hydrocarbons

Question 23

what is octane number system used for?

Answer 23

to give values of knocking resistance in the fuel

Question 24

octane number of cars, aviation fuel, racing cars?

Answer 24

-cars 89
-aviation fuel 100
-racing car 110

Question 25

the higher the octane number…?

Answer 25

the higher the fuel quality the lower the knock rate when burning

Question 26

which compound will be the first to distill out of a mixture?

Answer 26

a compound that has the lowest boiling point