Question

A first-stage recovery of magnesium from seawater is precipitation of Mg(OH)2 with CaO:

Mg2+(aq)+CaO(s)+H2O(l)→Mg(OH)2(s)+Ca2+(aq)

What mass of CaO , in grams, is needed to precipitate 1010 lb of Mg(OH)2 ?
Express your answer using four significant figures.

Answer 1

The mass of CaO, in grams, that is needed to precipitate 1010 lb of Mg(OH)₂ from the reaction is 442330.41 g

Balanced equation

Mg²⁺(aq) + CaO(s) + H₂O —> Mg(OH)₂(s) + Ca²⁺(aq)

Molar mass of CaO = 40 + 16 = 56 g/mol

Mass of CaO from the balanced equation = 1 × 56 = 56 g

Molar mass of Mg(OH)₂ = 24 + 2[16 + 1] = 58 g/mol

Mass of Mg(OH)₂ from the balanced equation = 1 × 58 = 58 g

SUMMARY

From the balanced equation above,

58 g of Mg(OH)₂ were precipitated by 56 g of CaO

How to determine the mass of CaO needed

1010 lb of Mg(OH)₂ = 1010 × 453.592

1010 lb of Mg(OH)₂ = 458127.92 g

From the balanced equation above,

58 g of Mg(OH)₂ were precipitated by 56 g of CaO

Therefore,

458127.92 g of Mg(OH)₂ will be precipitated by = (458127.92 × 56) / 58 = 442330.41 g of CaO

Thus, 442330.41 g of CaO is needed for the reaction.

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Answer 2

In the first-stage recovery of magnesium from seawater, 4.405 × 10⁵ g of CaO are required to precipitate 1010 lb of Mg(OH)₂.

What is stoichiometry?

Stoichiometry refers to the relationship between the quantities of reactants and products before, during, and following chemical reactions.

• Step 1: Write the balanced equation.

Mg²⁺(aq) + CaO(s) + H₂O(l) → Mg(OH)₂(s) + Ca²⁺(aq)

• Step 2: Convert 1010 lb of Mg(OH)₂ to g.

The required conversion factor is 1 lb = 453.592 g.

1010 lb × 453.592 g/1 lb = 4.581 × 10⁵ g

• Step 3: Calculate the mass of CaO required to precipitate 4.581 × 10⁵ g of  Mg(OH)₂.

The mass ratio of CaO to Mg(OH)₂ is 56.08:58.32.

4.581 × 10⁵ g Mg(OH)₂ × 56.08 g CaO/58.32 g Mg(OH)₂ = 4.405 × 10⁵ g CaO

In the first-stage recovery of magnesium from seawater, 4.405 × 10⁵ g of CaO are required to precipitate 1010 lb of Mg(OH)₂.

Learn more about stoichiometry here: https://brainly.com/question/16060223