Answer is: mass of calcium hydroxide is 46.98 grams.
Balanced chemical reaction: CaO + H₂O → Ca(OH)₂.
m(CaO) = 35.55 g.
n(CaO) = m(CaO) ÷ M(CaO).
n(CaO) = 35.55 g ÷ 56 g/mol.
n(CaO) = 0.634 mol; limiting reactant.
m(H₂O) = 125 mL · 1.000 g/mL.
m(H₂O) = 125 g.
n(H₂O) = 125 g ÷ 18 g/mol.
n(H₂O) = 6.94 mol.
From chemical reaction: n(CaO) : n(Ca(OH)₂) = 1 : 1.
n(Ca(OH)₂) = 0.634 mol.
m(Ca(OH)₂) = 0.634 mol · 74.1 g/mol = 46.98 g.
Answer:
The density of a substance that has a mass of 75 g and a volume of 35 mL is 2.14 
Explanation:
Density is a characteristic property of a substance that relates to the amount of mass it has per unit volume. In other words, density is the property that matter, whether solid, liquid or gas, has to compress into a given space (it measures the amount of mass in a given volume of a substance). It is calculated as the quotient between the mass of a body and the volume it occupies:

In this case, you know:
Replacing:

Solving:

<u><em>The density of a substance that has a mass of 75 g and a volume of 35 mL is 2.14 </em></u>
<u><em></em></u>
To convert from grams to moles, you must divide the given mass by the molecular weight. If this is so, then:
Water ≈ 18.02 grams/mol.
85.0 g/ 18.02 g/mol ≈ 4.72 moles