Exercise 1 solution

(a) NaHCO3 + H+ -> Na+ + CO2 + H2O (the equation given in the Sodium bicarbonate article). The H+ comes from the acid (the lemon juice). Chapter 8 explains why: baking soda is a base, and a base needs an acid to react with. Chapter 6 explains the equation: atoms and charge balance on both sides.

(b) Moles of NaHCO3 = 5.0 g / 84.01 g/mol = 0.0595 mol (Python: 0.0595).
The equation is 1 : 1 for NaHCO3 to CO2, so 0.0595 mol of CO2 at most.
Mass of CO2 = 0.0595 mol x 44.01 g/mol = 2.62 g (Python: 2.62). This is the maximum, if the acid is not limiting (Chapter 7).

(c) Chemical change (Chapter 1): a new substance, a gas (CO2), forms. It is not just a change of state.

Check: 5.0 / 84.01 and 0.0595 x 44.01 were run in Python. The 1 : 1 ratio is read from the page's equation.