Chemistry Lab Essay

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Hess's Law Lab Report Purpose Data and Observations Part I Heat of Solution of Solid Sodium Hydroxide Table 1 Original temperature of water (t1) 21.0ºC Final temperature of solution (t2) 26.0ºC Temperature change (t2-t1=∆t) 5.0ºC Mass of 100 mL of water 100.0g Heat evolved by reaction 2092J Mass of NaOH(s) 2.0g Moles of NaOH 0.05001250313 moles Energy per mole of NaOH 41829.52 J/mole ∆ H1 (kJ/mole) NaOH 41.83 kJ/mole Part II Heat of Reaction between Hydrochloric Acid and Sodium Hydroxide Solution Table 2 Original temperature of HCl(aq) 21.0ºC Original temperature of NaOH(aq) 21.0ºC Average original temperature (t1) 21.0ºC Final temperature of solution (t2) 34.5ºC Temperature change (t2 - t1 = ∆t) 13.5ºC Total mass of solution (assume 1mL = 1 g) 100.1g Heat evolved by reaction 5648.64 J Molarity of NaOH solution 2.0 M Volume of NaOH solution 0.05 L Moles of NaOH 0.1 moles Energy per mole of NaOH 56486.4 J/mole ∆H2 (kJ/mole) NaOH 56.49 kJ/mole Part III Heat of Reaction between Hydrochloric Acid and Solid Sodium Hydroxide Table 3 Original temperature of HCl(aq) (t1) 21.0ºC Final temperature of solution (t2) 34.0ºC Temperature change (t2 - t1 = ∆t) 13.0ºC Mass of HCl (assume 1 mL = 1g) 101.46g Heat evolved by reaction 5513.34 J Mass of NaOH(s) 2.0g Moles of NaOH 0.05001250313 moles Energy per mole of NaOH 110239.23 J/mole ∆H3 (kJ/mole) NaOH 110.24 kJ/mole Questions and Calculations Reaction 1: ∆T=26˚C-21˚C ∆T= 5˚C Cw=4.184J/(g˚C) qw=(100.0g)(4.184J/(g˚C))(26˚C-21˚C) qw=2092J -qrxn=qsolution qrxn=-2092J nNaOH=2.00g×(1 mole)/39.99g=0.05001250313 mols ∆H=qrxn/n=(-2092 J)/(0.05001250313 mols)×1kJ/(1000 J)= ∆H=-41.83 kJ/mole Reaction 2: mass=48.9g+54.2g=103.1g ∆T=34.5˚C-21˚C=13.5˚C Cw=Csolution=4.184J/(g˚C) qsolution=(103.1g)(4.184 J/(g˚C))(34.5˚C-21˚C) qsolution=5823.5 J -qrxn=qsolution

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