Calculate the number of mole of CaCl2 obtained from 25g of limestone CaCO3 in the pressure of excess HCl (C=,12, O=16, Cl=35.5)

Answer 1

that's "presence" not "pressure"
Figure how many moles of CaCO3 you have in 25g
Now, looking at the reaction equation:
CaCO3 + 2HCl = CaCl2 + H2O + CO2
you can see that each mole of CaCO3 produces one mole of CaCl2
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