27 – Synthesising & Investigating Benzoic Acid (LC 2027) (Leaving Cert Chemistry): Quizzes
📚Quizzes
Practise the questions
12 questions from this quiz
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Practise the questions
12 questions from this quiz
What is the molecular formula of benzoic acid?
What is the molecular formula of benzoic acid?
What is the E-number for sodium benzoate used as a food preservative?
What is the E-number for sodium benzoate used as a food preservative?
E211
Which oxidizing agent is used to synthesize benzoic acid from phenylmethanol?
Which oxidizing agent is used to synthesize benzoic acid from phenylmethanol?
Potassium permanganate
What color change occurs during the oxidation reaction?
What color change occurs during the oxidation reaction?
Purple to brown
What intermediate product forms under alkaline conditions before acidification?
What intermediate product forms under alkaline conditions before acidification?
Sodium benzoate
Why is hydrochloric acid added during the synthesis?
Why is hydrochloric acid added during the synthesis?
To convert sodium benzoate to benzoic acid
What principle does recrystallization rely on?
What principle does recrystallization rely on?
Different solubilities at different temperatures
What is the purpose of hot filtration during recrystallization?
What is the purpose of hot filtration during recrystallization?
Remove insoluble impurities
Why should minimum hot water be used in recrystallization?
Why should minimum hot water be used in recrystallization?
To maximize crystal yield upon cooling
What is the sharp melting point of pure benzoic acid?
What is the sharp melting point of pure benzoic acid?
121-122°C
What indicates the presence of impurities in a melting point test?
What indicates the presence of impurities in a melting point test?
Lower melting point and wider range
If 2.5 g of impure benzoic acid yields 2.25 g pure crystals, what is the percentage yield?
If 2.5 g of impure benzoic acid yields 2.25 g pure crystals, what is the percentage yield?
90%
