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Many modern antiseptics are based on phenol - Scottish Highers Chemistry - Question 12 - 2018
Question 12
Many modern antiseptics are based on phenol. The table shows the germ-killing power of some phenol compounds. (a) Compound Structure Germ-killing power (relative t... show full transcript
Worked Solution & Example Answer:Many modern antiseptics are based on phenol - Scottish Highers Chemistry - Question 12 - 2018
Step 1
Suggest two ways in which structural features increase germ-killing power of phenol compounds.
Answer
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Increasing the number of chlorine substituents can enhance the germicidal properties, as chlorine groups tend to increase the reactivity of the phenolic compound.
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Adding alkyl groups, such as larger or straight-chain hydrocarbons, can improve penetration through bacterial membranes, thus enhancing effectiveness.
Step 3
Calculate the mass of phenol, in kg, produced from 117 kg of benzene if the percentage yield is 90%.
Answer
To calculate the mass of phenol produced:
- Calculate the theoretical yield.
The molar mass of benzene (C₆H₆) = 78 g/mol.
Mass of benzene = 117 kg = 117,000 g.
Moles of benzene = ( \frac{117,000 ext{ g}}{78 ext{ g/mol}} = 1500 ext{ mol} ).
From the reaction, 1 mol of benzene produces 1 mol of phenol (C₆H₅OH).
- Therefore, the theoretical yield of phenol = 1500 mol.
The molar mass of phenol = 94 g/mol.
Theoretical mass of phenol = ( 1500 ext{ mol} \times 94 ext{ g/mol} = 141,000 ext{ g} ).
- Since the yield is 90%, the actual mass produced = 90% of 141,000 g = 126,900 g = 126.9 kg.