Question

calcium hydroxide is manufactured by heating calcium carbonate strongly to produce calcium oxide, and then adding a controlled amount of water to produce calcium hydroxide.
CaCO3(s)=CaO(s)+CO2(g)
CaO(s)+H2O(i)=Ca(OH)2(s)
a.) what mass of water would you produce from 1 tonne of calcium carbonate?
b.) what mass of water would you need to add to that calcium oxide?
c.) What mass of calcium hydroxide would you eventually produce?
(RAMs: H=1, C=12, O=16, Ca=40.)

Answer 1

a)

It is impossible to produce water from calcium carbonate, but if you mean what mass of water is necessary to treatment of 1 tonne of calcium carbonate to calcium hydroxide, I found the solution (below).

The molar mass of calcium carbonate is $\mathrm{M}(\mathrm{CaCO}_3) = 40 + 12 + 3*16 = 100\ \mathrm{g/mol}$

We have $\mathrm{n}(\mathrm{CaCO}_3) = \mathrm{m}(\mathrm{CaCO}_3)/\mathrm{M}(\mathrm{CaCO}_3) = 1000000\ \mathrm{g}/100\ \mathrm{g/mol} = 10000\ \mathrm{mol}$ of calcium carbonate.

$\mathrm{CaCO}_3(\mathrm{s}) = \mathrm{CaO}(\mathrm{s}) + \mathrm{CO}_2(\mathrm{g})$ (1)

$\mathrm{CaO}(\mathrm{s}) + \mathrm{H}_2\mathrm{O}(\mathrm{l}) = \mathrm{Ca}(\mathrm{OH})_2(\mathrm{s})$ (2)

According to the equation (1) and (2) we need one mol of water for 1 mol of calcium carbonate, hence we have:

$\mathrm{n(H_2O) = n(CaCO_3) = 10000mol}$

The mass of water is:

$\mathrm{m(H_2O) = n(H_2O)*M(H_2O) = 10000mol*18g/mol = 180000\ g = 180\ kg}$

b) The mass of water that you need to add to the calcium oxide is equal to previous solution.

$\mathrm{M(water) = 180\ kg}$

c)

The molar mass of calcium carbonate is $\mathrm{M}(\mathrm{CaO}) = 40 + 16 = 56\ \mathrm{g/mol}$

According to the equation (1) and (2) we need 1 mol of CaO for 1 mol of calcium carbonate, hence we have:

$\mathrm{n(CaO) = n(CaCO_3) = 10000mol}$

The mass of CaO is:

$\mathrm{m(CaO) = n(CaO)*M(CaO) = 10000mol*56g/mol = 560000\ g = 560\ kg}$