Calculate to four decimal places the mass of pure dry CaCO3 required to make 1 L of a 1000

ppm Ca stock solution.

1 answer

1000 ppm, means 1000g
1000 ppm means .001g of Ca+2 ion, or .001/ 40.078 moles Ca, so you want then the same number of moles of C and O3

element, moles, mass
Ca, .001/40.078, .001g
C, ibid times 12.0107, 0.000299683118
3O, ibid times 3*15.9994, 0.00119761964

Now adding up the masses,
0.00119761964+.001+.000299683118
I get 0.00249730276 grams of CaCO3. Now, is the mass of a liter of solution to four decimal places really 1000g? No, depends on temperature, it varies some. So you have to have temperature given. http://water.usgs.gov/edu/density.html

check my work