Respostas

2014-02-10T17:44:14-02:00
Mg(OH)2 --> Massa Molar = 58,3g/mol.

Massa Molar Mg = 24,3g/mol.

Regra de 3 

58,3 ------------- 100% = 1
24,3 --------------- x

24,3*1 = 58,3x

x = 24,3/58,3
x = 0,416 = 41,6% (valor aproximado).

5,8g de Mg(OH)2 --------------- 100% = 1
x g de Mg --------------------------41,68% = 0,4168 ~= 0,42


x = 0,42*5,8

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x = 2,436 gramas de Magnésio.
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