Question

Ninety-eight percent of an eggshell is calcite, which is calcium carbonate. Calcium is the major component of bone as well (in the form of calcium phosphate, or apatite). The calcium that goes into the shell comes both from the hen’s diet and from her bones. Weigh the shell. (Our shell weighs 6.25 grams) Realize that a truly remarkable hen can lay an egg a day. Approximately how much calcium will a one-a-day hen lose in a week? In a year, a hen can put into her eggshells over 25 times her own skeletal weight in calcium. Obviously, this must be replaced. The standard feed given to laying hens is 3 to 4% calcium, and one hen receives about a 100 gm of feed a day. Based on the weight of the shell, is this sufficient to replace the calcium lost in a superhen laying every day?

Answer 1

Mass of egg shell = 6.25 g

mass of CaCO₃ = 6.25 g

moles of CaCO₃ = (mass of CaCO₃) / (molar mass of CaCO₃)

moles of CaCO₃ = (6.25 g) / (100.0869 g/mol)

moles of CaCO₃ = 0.06245 mol

moles of Ca = moles of CaCO₃

moles of Ca = 0.06245 mol

mass of Ca = (moles of Ca) * (molar mass Ca)

mass of Ca = (0.06245 mol) * (40.078 g/mol)

mass of Ca = 2.503 g

mass of Ca lost in a week = (2.503 g) * 7

mass of Ca lost in a week = 17.52 g

mass of feed for one day = 100 g

% Ca in feed = 3% to 4%

mass of Ca in feed for one day = (mass of feed for one day) * (% Ca in feed)

mass of Ca in feed for one day = (100 g) * (3% to 4%)

mass of Ca in feed for one day = 3 grams to 4 grams

mass of Ca in feed for one week = (mass of Ca in feed for one day) * 7

mass of Ca in feed for one week = (3 grams to 4 grams) * 7

mass of Ca in feed for one week = 21 grams to 28 grams

Since mass of calcium lost (17.52 g) is less than mass of calcium given in feed (21 grams to 28 grams), therefore calcium lost in laying eggs is sufficiently replaced by calcium in feed.