How do i determine the enthalpy of decomposition of Sodium hydrogen carbonate

How do you determine the enthalpy of decomposition of Sodium Hydrogen Carbonate after findind enthalpy change of the reactions between "hcl and NaHCO3" & "HCl and Na2CO3 & HCl". I know im supposed use a hess cycle to do that but got no clue. thanx in advance

Reply 1

charco

Study Forum Helper

decomposition of sodium hydrogen carbonate
2NaHCO3 ---> Na2CO3 + CO2 + H2O

react

NaHCO3 + HCl ---> NaCl + CO2 + H2O
and
Na2CO3 + 2HCl --> 2NaCl + CO2 + H2O

multiply equn 1 by 2 and subtract equn 2 from the result then rearrange:
2NaHCO3 + 2HCl ---> 2NaCl + 2CO2 + 2H2O
Na2CO3 + 2HCl --> 2NaCl + CO2 + H2O
----------------------------------------
2NaHCO3 ----> Na2CO3 + CO2 + H2O

so if you experiment to find the enthalpy change of reaction for
2NaHCO3 + 2HCl ---> 2NaCl + 2CO2 + 2H2O

and then experiment to find the enthalpy change for reaction
Na2CO3 + 2HCl --> 2NaCl + CO2 + H2O

you can just perform the same calculation with the enthalpy values to get that for decomposition.

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