C7 Flashcards

To boss C7

1
Q

What type of molecule is an alkane?

A

A fully saturated hydrocarbon.

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2
Q

What is the general formula for an alkane?

A

C n H 2n+2

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3
Q

Name the first four alkanes.

A

Methane, Ethane, Propane, Butane

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4
Q

Alkanes combust to give…

A

… Carbon dioxide and water

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5
Q

How reactive are alkenes?

A

Very (they’re unsaturated i.e. C=C double bonds)

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6
Q

How can you differentiate alkanes and alkenes?

A

Bromine water test - Alkanes stay the same but alkenes form two clear layers (bromine water + haloaklane)

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7
Q

What is the difference between aliphatic and aromatic compounds?

A

Aliphatic compounds are straight, aromatic compounds are circular chains.

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8
Q

What is the functional group in alcohols?

A

-OH (hydroxyl group)

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9
Q

Describe the relative reactivity of water, alcohols and alkanes with sodium.

A

Water - forms sodium hydroxide and hydrogen. very reactive.
Alkanes - not much happens. Unreactive.
Alcohols - slow reaction but sodium ethoxide/methoxide is produced along with hydrogen.

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10
Q

What are some uses of alcohols?

A

Cleaning, antibacterials, fuel, fragrance, getting plastered…

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11
Q

What is the functional group in a carboxylic acid?

A

-COOH (carboxyl group)

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12
Q

How can esters be produced?

A

Alcohol + Carboxylic acid -> Ester + hydrogen

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13
Q

How can ethanoic acid be produced?

A

Oxidation of hydrocarbons (low efficiency) or Monsanto process (high efficiency, ethanoic acid heated with carbon monoxide)

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14
Q

What are the requirements for ethanol production via fermentation?

A

30 degrees C, pH 4, and no oxygen should get into the process to avoid ethanoic acid production

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15
Q

What are the requirements for ethanol production via biomass?

A

35 degrees C, pH 6

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16
Q

What are the requirements for ethanol production via ethene steam hydration?

A

300 degrees C, 70 atmospheres pressure, phosphoric acid catalyst

17
Q

Name and describe the four stages of ester production.

A

Reflux - carboxylic acid, alcohol, sulfuric acid heated with condenser. Recycled into flask.
Distillation - Heat mixture below fractionating column. Set temperature to boiling point of ester.
Purify - shake mixture in tap funnel with sodium carbonate to remove acids, calcium chloride solution to remove alcohol. Remove bottom layers.
Drying - Remove water using anhydrous calcium chloride. The pure ester is then filtered off.

18
Q

Fats and oils can be made from which acid and which alcohol?

A

Glycerol + fatty acid

19
Q

What is the difference between fats and oils?

A

Oils are generally from plants and are liquid at room temp. They have lots of unsaturated bonds.
Fats are generally from animals and are solid at room temp. They have lots of saturated bonds.

20
Q

What is the difference between exothermic and endothermic reactions?

A
Exothermic = energy released
Endothermic = energy taken in
21
Q

What is activation energy?

A

Energy required to start a reaction

22
Q

Energy is supplied when bonds need to be…

A

Broken

23
Q

Describe he concept of a dynamic equilibrium.

A

If a reversible reaction occurs in a closed system, a dynamic equilibrium results. This means that the relative quantities of the reactants and products reach a balance. The reactions still occur but there is no net change.

24
Q

What is the formula for the Haber process? What are the conditions?

A

N2 + 3H2 2NH3
Unused reactants are recycled.
The conditions are 200 atm, 450 degrees C, and with an iron catalyst.
Higher pressures favour the forward reaction, but if it gets too high the costs become prohibitive. Increasing temperature increases the rate of reaction, but reduces yield. Lots of compromises…

25
Q

Nitrogen fixation turns nitrogen gas into ammonia. The Haber process does this too, mainly for fertilisers - why is this a problem?

A

Fertilisers can pollute water supplies and cause eutrophication. (Ammonia can also be used in plastic, explosive, and pharmaceutical industries)

26
Q

Nitrogen fixation can be speeded up using enzymes at room temperature. Chemists currently use iron catalysts, but what are they trying to do?

A

They are trying to find catalysts that function like enzymes, so the Haber process can occur at room temperature. This would be cheap and efficient.