you find the molecular formula of Fe203 (24x2 + 16 x 3=100)

you then divide 374 by 100= 3.74

since there are 3 times as many H20's you must multiply 3.74 by 3

3.74 x 3=11.22 moles

you then work out the molecular formula of H2O (1+1+16=18)

you then multiply 11.22 by 18 to get 201.96

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