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 4.93 1010 kg of calcium hydrogen carbonate was produced?
would the correct answer be 3.04e13??
i found this by taking 4.93e10kg converting it to grams= 4.93e13g Ca(HCO3)2 then converting that to moles and then setting that equal to limestone (CacCO3) and converting that then to grams.
See comments above.
To find the mass of limestone that must have dissolved, you need to use stoichiometry to relate the mass of calcium hydrogen carbonate (Ca(HCO3)2) produced to the mass of limestone (CaCO3) that dissolved.
First, convert the mass of calcium hydrogen carbonate (Ca(HCO3)2) produced from kilograms to grams:
4.93 x 10^10 kg * 1000 g/kg = 4.93 x 10^13 g
Next, use the balanced chemical equation:
CaCO3(s) + H2CO3(aq) → Ca(HCO3)2(aq)
Based on the equation, you can see that the molar ratio between Ca(HCO3)2 and CaCO3 is 1:1.
Now, calculate the molar mass of Ca(HCO3)2 by adding the atomic masses of each element:
The molar mass of Ca = 40.08 g/mol
The molar mass of H = 1.01 g/mol (x 2 for 2 atoms of hydrogen) = 2.02 g/mol
The molar mass of C = 12.01 g/mol
The molar mass of O = 16.00 g/mol (x 5 for 5 atoms of oxygen) = 80.00 g/mol
Total molar mass of Ca(HCO3)2 = 40.08 g/mol + 2.02 g/mol + 12.01 g/mol + 80.00 g/mol = 134.11 g/mol
Calculate the number of moles of Ca(HCO3)2:
Moles of Ca(HCO3)2 = mass / molar mass = 4.93 x 10^13 g / 134.11 g/mol
Finally, since the molar ratio between Ca(HCO3)2 and CaCO3 is 1:1, the mass of CaCO3 that dissolved is also equal to 4.93 x 10^13 g.
Therefore, the correct answer is 4.93 x 10^13 g, which is the same result you obtained. Well done!