Phenol, C₆H₅OH (94 g/mol), reacts with an excess of bromine water and gives a white precipitate of…

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Phenol, $\text{C}_{6}\text{H}_{5}\text{OH}$ ( $94\ \text{g/mol}$ ), reacts with an excess of bromine water and gives a white precipitate of 2,4,6-tribromophenol, $\text{C}_{6}\text{H}_{2}\text{Br}_{3}\text{OH}$ . A student uses 0.94 g of phenol. Use Br = 80 in g/mol. Find the amount of bromine needed, the greatest mass of the white precipitate, and the mass collected if the yield is $80\ \%$ .

Need a reminder? The key ideaShow

Bromine adds across one double bond for each molecule of $\text{Br}_2$ , and a phenol takes three. Tollens' reagent gives $2\ \text{Ag}$ for each $\text{RCHO}$ , and Fehling's solution gives one $\text{Cu}_2\text{O}$ . The iodoform test is positive for $\text{CH}_3\text{CO-}$ and $\text{CH}_3\text{CH(OH)-}$ .

The worked solution

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← A student shakes 4.2 g of hex-1-ene, C₆H₁₂ (84 g/mol), with bromine water of concentration 0.20…A sample of 0.58 g of propanal, CH₃CH₂CHO (58 g/mol), is divided so that the whole amount is tested… →

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