Question

Lab 14 Molar Volume of Gases:

Find the molar mass of the NaHCO3 using the following info, show calculations:

Barometric pressure (atm): 1.013

Temperature (°C): 18

Mass of Chemical (g): 1.0g

Water Displaced: 206mL

Find the molar mass of Na2CO3 using the following info, show calculations:

Barometric pressure (atm): 1.013

Temperature (°C): 18

Mass of Chemical (g): 1.0g

Water Displaced: 168mL

Answer 1

Q1.

2NaHCO3 + heat --> Na2CO3 + CO2(g) + H2O(g)

so..

total volume of gas = 206 mL

PV = nRT

n = PV/(RT)

n = (1.013)(206*10^-3)/(0.082*(18+273)) = 0.008745 mol of gases

so..

2 mol of Na2HCO3 = 1 mol of CO2 + 1 mol of H2O

so... ratio is 2:2

0.008745 mol of gases = 0.008745 mol of solid

MW= mass/mol = (1)/0.008745 = 114.351 g/mol of NAHCO3

Q2.

Na2CO3 + heat --> Na2O + CO2

similar...

n = (1.013)(168*10^-3)/(0.082*(18+273)) = 0.0071320 mol of gases

1:1 ratio so

MW = mass/mol= 1/0.0071320 = 140.2 G/mol