Question

Sodium hydrogen carbonate, on heating, produces sodium carbonate, water and carbon dioxide.

A recipe for chocolate chip cookies requires 1.5 dm' of carbon dioxide.
Calculate the mass of sodium hydrogen carbonate that should be used at R.T.P.
INa = 23; H = 1: C = 12; O = 16.]
[Note that 1 mole of gas occupies a volume of 24,000 cm at room temperature and pressure (RTP)]​

Answer 1

The mass of sodium hydrogen carbonate : 10.5 g

Further explanation

Given

1.5 dm' of CO₂

1 mol gas= 24 L at RTP(25 °C, 1 atm)

Required

the mass of sodium hydrogen carbonate

Solution

Decomposition reaction of Sodium hydrogen carbonate :

2 NaHCO₃ (s) ⇒ Na₂ CO₃ (s) + H₂ O(g) + CO₂ (g)

mol CO₂ :

`\tt mol=(1.5)/(24)=0.0625`

From the equation, mol ratio of NaHCO₃ : CO₂ (g) = 2 : 1, so mol NaHCO₃ :

`\tt 2* 0.0625=0.125`

Mass NaHCO₃(MW=23+1+12+3.16=84 g/mol) :

`\tt mass=mol* MW\\\\mass=0.125* 84\\\\mass=10.5`