# For calcium hydroxide, find the “building” synonyms for its varieties. Calculate the mass fraction of metals

For calcium hydroxide, find the “building” synonyms for its varieties. Calculate the mass fraction of metals for these bases according to their formulas. Slaked lime (it is obtained by quenching calcium oxide with water), lime water (is a transparent aqueous solution), fluff (calcium hydroxide in the form of a dry powder), milk of lime (a suspension of hydroxide in water).
Calculate the mass fraction of metals for these bases according to their formulas.
Given: Mg (OH) 2 and Ca (OH) 2. Find: ω (Mg) – ?, ω (Ca) -?
Decision.
1. Mass fraction of magnesium in Mg (OH) 2.
Mr (Mg (OH) 2) = Ar (Mg) + 2 • Ar (O) + 2 • Ar (H) = 24 + 2 • 16 + 2 • 1 = 58
ω (Mg) = (Ar (Mg) / Mr (Mg (OH) 2)) • 100% = (24:58) • 100% = 41.38%
2. Mass fraction of calcium in Ca (OH) 2.
Mr (Ca (OH) 2) = Ar (Ca) + 2 • Ar (O) + 2 • Ar (H) = 40 + 2 • 16 + 2 • 1 = 74
ω (Ca) = (Ar (Ca) / Mr (Ca (OH) 2)) • 100% = (40:74) • 100% = 50.05%
Answer: ω (Mg) = 41.38%, ω (Ca) = 50.05%. Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.