Alcohols Flashcards

Question

Disadvantages of fermentation

Answer 1

• Batch process which is slow and gives high production costs • Ethanol made is not pure and needs purifying by fractional distillation • Depletes land used for growing food crops

Answer 2

C2H4 + H2O -> C2H5OH

Answer 3

Hydration/addition

Answer 4

The addition of a water to a molecule

Answer 5

• High temps 300*C • High pressure 70atm • Strong acidic catalyst of conc H3PO4

Answer 6

• Faster reaction • Purer product • Continuous process (cheaper)

Answer 7

• High technology needed (expensive initial costs) • Ethene is a non-renewable resource (will become more expensive when raw materials run out) • High energy cost for pumping to produce high pressures

Answer 8

A fuel produced from plants

Answer 9

An activity that has no net annual carbon (greenhouse gases) emissions to the atmosphere

Answer 10

Because any carbon dioxide given off when the biofuel is burnt would have been extracted from the air by photosynthesis when the plant grew -> there would be no jet CO2 emission into the atmosphere

Answer 11

Removal of CO2 by photosynthesis: **6CO2** + 6H2O -> C6H12O6 + 6O2 Production of CO2 by fermentation and combustion: C6H12O6 -> 2C2H5OH + **2CO2** 2C2H5OH + 6O2 -> **4CO2** + 6H2O Overall for every 6 molecules of CO2 absorbed, 6 molecules of CO2 are emitted -> there’s no net contribution of CO2 to the atmosphere

Answer 12

Any energy needed to irrigate plants, fractionally distil the ethanol from the reaction mixture or process the fuel -> if the energy for these processes comes from fossil fuels then the ethanol produced is not carbon neutral

Answer 13

**Distillation** 1. Add concentrated sulfuric, phosphoric acid and cyclohexanol into a **round bottomed flask** -> add anti bumping granules 2. Use a **heating mantle** to warm reactants up to 83*C (the bp of cyclohexanol) 3. Chemicals with bps less than 83*C will evaporate, enter the condenser, cool down and condense back into a liquid 4. The product is distilled in a conical flask -> however this product will still have impurities such as unreacted cyclohexanol and water

Answer 14

It has cold running water running through its wall

Answer 15

Because cyclohexanol is flammable We use a heating mantle instead of

Answer 16

Step 2: **Separation** 1. Add the products from step 1 into a separating funnel -> add water to dissolve soluble impurities and create an aqueous solution 2. After allowing the solution to settle, 2 layers will form: **Top layer** - impure cyclohexene **Bottom layer** - aqueous layer containing water soluble impurities -> drain the aqueous layer off

Answer 17

Step 3: **Purification** 1. Take the impure cyclohexene from step 2 and add to a round bottomed flask 2. Add anhydrous calcium chloride -> invert the flask and leave for 30 minutes

Answer 18

Because it is a **dehydrating agent** and will remove any aqueous substances still remaining

Answer 19

Exothermic

Answer 20

It’s an enzyme that converts glucose into carbon dioxide and ethanol

Answer 21

• They are renewable and more sustainable than crude oil • They produce CO2 when burnt but they are classed as carbon neutral as the CO2 is absorbed by the sugar cane in photosynthesis

Answer 22

• Expensive to convert existing petrol engines to take fuels with higher concentrations of ethanol • Land that could have been used to grow food is being used to make fuel -> could cause food shortages

Answer 23

Because it just produces carbon dioxide and water -> no useful products

Answer 24

Because aldehydes have a lower boiling point than alcohols

Answer 25

It allows strong heating without losing volatile reactants and products -> aldehydes evaporate, condense and fall back into the flask

Alcohols Flashcards

(50 cards)