I want to find out if my reasoning is correct...

I want to calculate the enthalpy change of this reaction

NaHCO3 + HCl -> NaCl + CO2 + H2O

...using Hess's Law...

1) 2NaHCO3 -> Na2CO3 + CO2 + H2O

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

1) 7g of hydrogencarbonate

50cm^3 of hydrochloric acid

deltaT=5K

2) 4g of hydrogencarbonate

50cm^3 of hydrochloric acid

deltaT=9,5K

2H1=H2+H3

H2= 0,057 x 4,18 x 5 = -1,19kJ

H3=0,054 x 4,18 x 9,5 = 2,14kJ

H1=(-1,19kJ - 2,14kJ):2= -1,665kJ

Is this correct?