Question

An experiment was to identify the unknown solution as sodium carbonate or sodium bicarbonate by reacting it with HCl and taking pressure measurements. My chemical equations are: NaHCO3+HCl--->CO2+H2O+NaCl Na2CO3+2HCl--->CO2+H2O+2NaCl. The instructor said that it can be determined by looking at the chemical equation. My response was the pressure measurements were from the unknown were closer to sodium bicarbonate than sodium carbonate. Is this a correct assumption?

Answer 1

for chemical equations are:

NaHCO3 + HCl ---> CO2 + H2O + NaCl

and

Na2CO3 + 2 HCl ---> CO2 + H2O + 2 NaCl

on comparing both reaction ,

if you will use same amount of HCl for these reactions then amount of CO2 produced will be less incase of Na2CO3 because for the similar amount of CO2 production 2 times of HCl will be required for the Na2CO3 reaction.

and also for one mole of sodium NaHCO3 has twice CO2 production than Na2CO3 therefore we have a higher CO2 pressure in case of the NaHCO3 than Na2CO3.

now you can see the reasons and say that if the pressure measurements were from the unknown were closer to sodium bicarbonate than sodium carbonate then your assumption is correct.