When the following equation is balanced, the stoichiometric coefficient of HNO3 is ________.HNO3(aq) + CaCO3(s) → Ca(NO3)2(aq) + CO2(g) + H2O(l)

To balance the given chemical equation, we need to ensure that the number of atoms of each element is the same on both sides of the equation.

The unbalanced equation is: HNO3(aq) + CaCO3(s) → Ca(NO3)2(aq) + CO2(g) + H2O(l)

Step 1: Balance the Ca atoms There is 1 Ca atom on both sides, so the Ca atoms are already balanced.

Step 2: Balance the C atoms There is 1 C atom on both sides, so the C atoms are already balanced.

Step 3: Balance the O atoms There are 3 O atoms in HNO3, 3 in CaCO3, 2 in Ca(NO3)2, 2 in CO2, and 1 in H2O. This gives a total of 6 O atoms on the left side and 5 O atoms on the right side. To balance the O atoms, we need 2 molecules of HNO3 on the left side. This gives us 6 O atoms on both sides. The equation now looks like this:

2HNO3(aq) + CaCO3(s) → Ca(NO3)2(aq) + CO2(g) + H2O(l)

Step 4: Balance the H atoms There are 2 H atoms in 2HNO3 and 2 H atoms in H2O. So, the H atoms are now balanced.

Step 5: Balance the N atoms There are 2 N atoms in 2HNO3 and 2 N atoms in Ca(NO3)2. So, the N atoms are now balanced.

So, the balanced equation is:

2HNO3(aq) + CaCO3(s) → Ca(NO3)2(aq) + CO2(g) + H2O(l)

Therefore, the stoichiometric coefficient of HNO3 is 2.