When surface water dissolves carbon dioxide, carbonic acid (H2CO3) is formed. When the water moves underground through limestone formations, the limestone dissolves and caves are sometimes produced.

CaCO3(s) + H2CO3(aq) Ca(HCO3)2(aq)

What mass of limestone must have dissolved if 1.98 1010 kg of calcium hydrogen carbonate was produced?

I answered your post under the screen name "pr" just below.

To determine the mass of limestone that dissolved, we can use stoichiometry and the given balanced chemical equation:

CaCO3(s) + H2CO3(aq) -> Ca(HCO3)2(aq)

From the equation, we can see that 1 mole of CaCO3 reacts with 1 mole of H2CO3 to produce 1 mole of Ca(HCO3)2.

Now let's set up the equation using the molar masses of the compounds involved:

1 mole of CaCO3 has a molar mass of 100.09 g/mol.
1 mole of Ca(HCO3)2 has a molar mass of 162.12 g/mol.

The molar ratio between CaCO3 and Ca(HCO3)2 is 1:1, which means that the mass of CaCO3 dissolved would be the same as the mass of Ca(HCO3)2 formed.

First, convert the given mass of calcium hydrogen carbonate (Ca(HCO3)2) to moles:

1.98 x 10^10 kg -> 1.98 x 10^13 g

Next, calculate the number of moles of Ca(HCO3)2:

n = m/M
n(Ca(HCO3)2) = (1.98 x 10^13 g) / (162.12 g/mol)

Now, since the molar ratio is 1:1 between CaCO3 and Ca(HCO3)2, the number of moles of CaCO3 dissolved would also be the same:

n(CaCO3) = n(Ca(HCO3)2)

Finally, calculate the mass of limestone (CaCO3):

m(CaCO3) = n(CaCO3) x M(CaCO3)
m(CaCO3) = n(Ca(HCO3)2) x M(CaCO3)
m(CaCO3) = (1.98 x 10^13 g) / (162.12 g/mol) x 100.09 g/mol

After performing the calculation, you will get the mass of limestone (CaCO3) that dissolved.