Question

Select the correct balanced equation for the double displacement reaction of calcium carbonate and hydrochloric

acid (Rolaids and stomach acid)
CaCO3 + HCL -> CaCl2 + H2CO3

Answer 1

B: CaCO3 + 2HCl -> CaCl2 + H2CO3

Step-by-step explanation:

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

Hope it helped!