The chemical formula for sodium hydrogencarbonate is NaHCO3. When it breaks down completely, it produces carbon dioxide (CO2), water (H2O), and sodium carbonate (Na2CO3).

The balanced chemical equation for the decomposition of sodium hydrogencarbonate is:

2NaHCO3(s) → CO2(g) + H2O(g) + Na2CO3(s)

From the balanced chemical equation, we can see that 2 moles of NaHCO3 produce 1 mole of CO2.

The molar mass of NaHCO3 is:

23 g/mol (Na) + 1 g/mol (H) + 12 g/mol (C) + 3(16 g/mol) (O) = 84 g/mol

So, 336 g of NaHCO3 is equivalent to:

336 g / 84 g/mol = 4 moles of NaHCO3

According to the balanced chemical equation, 4 moles of NaHCO3 will produce 2 moles of CO2.

The molar mass of CO2 is:

12 g/mol (C) + 2(16 g/mol) (O) = 44 g/mol

So, 2 moles of CO2 weighs:

2 moles * 44 g/mol = 88 g of CO2

Therefore, when 336 g of sodium hydrogencarbonate breaks down completely, it produces 88 g of carbon dioxide.