POM 9.2.3

Question 0

What is Electronegativity?

Answer 0

• The ability of an atom to attract electrons

- The more electronegative an atom, the stronger it will hold onto electrons in a chemical bond

Question 1

What is a polar covalent bond?

Answer 1

A bond were one of the atoms in it is more electronegative than the other so the bond has a slight charge

Question 2

What is the basic principle of the solubility rules?

Answer 2

• “Like dissolves like”
• Polar dissolves polar
• Non-polar dissolves non-polar

Question 3

Describe the dehydration of ethanol

Answer 3

• The chemical process whereby a water molecule is removed from ethanol, forming ethylene
• C2H5OH (l) –H2SO4–> C2H4 (g) + H20 (l)
• Conc sulfuric acid catalyst

Question 4

Describe the addition of water to ethylene

Answer 4

• Hydration of ethylene is the process whereby a water molecule is added to ethylene, forming ethanol
• C2H4 (g) + H20 (l) –H3PO4–> C2H5OH (l)
• Conc phosphoric acid catalyst

Question 5

Account for the many uses of ethanol as a universal solvent

Answer 5

• Ethanol is able to dissolve both polar and non-polar substances due to it’s molecular structure
• The OH- group is POLAR
• The CH3CH2+ group is NON-POLAR

Question 6

Advantages of ethanol

Answer 6

• Renewable resource

- “Greenhouse neutral”: the CO2 absorbed by the crop can match the CO2 produced by combustion

Question 7

Disadvantages of ethanol

Answer 7

• Engines must be modified to run on fuel containing more than 20% ethanol
• Engines wear down faster

Question 8

Describe the conditions under which fermentation of sugars is promoted. Include equations

Answer 8

• Fermentation is the process in which glucose is turned into ethanol and carbon dioxide by the action of enzymes
• C6H12O6 (aq) –yeast–> 2C2H5OH (aq) + 2CO2 (g)
  COND:
• Presence of yeast cultures
• Exclusion of air
• 37’C temperature

Question 9

Summarise the chemistry of the fermentation process

Answer 9

• Yeast is added to mashed grain an water
• The yeast breaks down the large carbohydrates into simple sugars
• These sugars are then fermented
• The yeast use their enzymes to break down the sugars, forming ethanol and CO2 as products

Question 10

Suffixes of naming more than one hydroxyl group

Answer 10

1 -ol
2 -diol
3 -triol
4 -tetraol