Дано
m(C6H5OH) = 58 g
m практ(C6H2Br3OH) = 256 g
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η (C6H2Br3OH)- ?
56 X g
C6H5OH+3Br2-->C6H2Br3OH+3HBr
94 331
M(C6H5OH)= 94 g/mol , M(C6H2Br3OH) = 331 g/mol
X = 56 * 331 / 94 = 197.2 g - масса теор.
η(C6H2Br3OH)= 197.2 / 256 * 100% = 77%
ответ 77%