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What is the mass percent of oxygen in Al2(SO4)3·18H2O? Molar mass Al2(SO4)3·18H2O is...

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lak-86 | Student, Undergraduate | Salutatorian

Posted August 17, 2013 at 1:30 AM via web

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What is the mass percent of oxygen in Al2(SO4)3·18H2O?

Molar mass Al2(SO4)3·18H2O is 666.43 g/mol

(A) 9.60

(B) 28.8

(C) 43.2

(D) 72.0

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jeew-m | College Teacher | (Level 1) Educator Emeritus

Posted August 17, 2013 at 1:37 AM (Answer #1)

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molar mass of oxygen is 16g/mol.

There are 30 oxygen moles inside 1mol of the compound `Al_2(SO_4)_3·18H_2O`

Mass of Oxygen in the compound `= 30xx16 = 480g`

Mass % of oxygen `= 480/666.43xx100% = 72%.`

So mass percentage of oxygen in `Al_2(SO_4)_3·18H_2O` is 72%.

The correct answer is at D)

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