Question

Question #fb855

Answer 1

`0.20 M`

Explanation:

1. The equation is
   `CaCO_3->CaO + CO_2`
2. Find the formula masses of `CO_2` and `CaCO_3`
   `CaCO_3`=`100` grams per mole
   `Ca=1`x`40=40`
   `C=1`x`12=12`
   `O=3`x`16=48`
   `CO_2`=`44` grams per mole
   `C=1`x`12=12`
   `O=2`x`16=32`
3. Find the mass of pure marble;
   `mass pure=(actual mass)(purity)`
   `mass pure=((10g)(0.50)`
   `mass pure=5 g`
4. Convert mass `CaCO_3` to mole `CaCO_3`
   `5 cancel(g CaCO_3)`x`(1 mol CaCO_3)/(100 cancel(g CaCO_3)`
   `0.05 mol CaCO_3`
5. Find the mol `CO_2`; referring to the equation it's observed that both compounds have same number of mole; thus
   `CO_2=0.05 mol`
6. Convert `250 ml` to Li; `0.25 Li`
7. Therefore, to find the Molarity(M) use the formula:
   `M=(n. mol)/(Li solution)`
   `M=(0.05 mol)/(0.25 Li)`
8. `M=0.20 (mol)/(Li)` or `0.20M`