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Chemistry Level 2

33.65 g 33.65\text{ g} of a magnesium salt contains 1 mol 1\text{ mol} of this element. As it's anion is trivalent, we can affirm that the mass for 1 mol 1\text{ mol} of anion is:

Molar mass for magnesium: 24.31 g/mol 24.31 \text{g/mol}

This question was seen on Military Institute of Engineering JEE.
48.32g 42.03g 14.01g 24.31g 6.03g

Lucas Nascimento by Lucas Nascimento , 24, Brazil

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1 solution

Lucas Nascimento
Jul 8, 2016

Being a trivalent anion, it's salt formula can be written as Mg 3 A 2 \text{Mg}_3\text{A}_2 .

From the given information, we can calculate de anion's mass on this amount of salt:

m A = 33.65 g − m M g m_A = 33.65g - m_{Mg}

As we know: m = M ∗ n \boxed {m=M*n}

m A = 33.65 g − n M g ∗ M M g m_A = 33.65g - n_{Mg}*M_{Mg} ⇒ \Rightarrow m A = 33.65 g − 1 m o l ∗ 24.31 g / m o l = 9.34 g m_A = 33.65g - 1mol * 24.31g/mol = 9.34g

As n M g 3 \frac{n_{Mg}}{3} = n A 2 \frac{n_A}{2} ⇒ \Rightarrow M A = 9.34 g ∗ 1.5 M_A= 9.34g * 1.5

M A = 14.01 g / m o l M_A= 14.01g/mol

For 1 mol: m A = 14.01 g \boxed {m_A = 14.01g}

2 Helpful 0 Interesting 0 Brilliant 0 Confused

Hey shouldnt be MG3A2?

Mr Yovan - 4 years, 10 months ago

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Of course! I'm sorry for my mistake.

Lucas Nascimento - 4 years, 8 months ago

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