Select the correct balanced equation for the double displacement reaction of calcium carbonate and hydrochloric
acid (Rolaids and stomach acid)
CaCO3 + HCL -> CaCl2 + H2CO3
Count how many elements they are in all molecules for the reactants and for the products.
For the reactants:
Ca = 1 element
C = 1 element
O = 3 elements
H = 1 element
Cl = 1 element
For the products:
Ca = 1 element
Cl = 2 elements
H = 2 elements
C = 1 element
O = 3 elements
To balance this equation, we need to add 1 more element of Chlorine and Hydrogen. Therefore, we add a 2 to the coefficient of HCl for the reactants side.
Now let us try it.
CaCO3 + 2HCl -> CaCl2 + H2CO3
Count how many elements they are in all molecules for the reactants and products.
For the reactants:
Ca = 1 element
C = 1 element
O = 3 elements
H = 2 element
Cl = 2 element
For the products:
Ca = 1 element
Cl = 2 elements
H = 2 elements
C = 1 element
O = 3 elements
All of the elements are balanced.
So the final answer is B: CaCO3 + 2HCl -> CaCl2 + H2CO3
