# Thermochemistry And Hess's Law Essay

590 WordsMay 2, 20123 Pages
Thermochemistry and Hess's Law Problem- What chemical experiment will give the best enthalpy change? Hypothesis- I think that NaOH+HCL will give the greatest empathy change. Materials: HCL 2.0M NaOH 2.0M NH3 2.0M ` NH4Cl Graduated Cylinder Beaker Styrofoam Cups Fume Hood Hot plate Thermometer Procedure- HEAT CAPACITY OF THE CALORIMETER measure 50 ml of room temperature water in the Styrofoam cup take the temperature heat 50 ml of water until it reaches 70oC mix room temperature with hot water add another Styrofoam cup to keep the heat from escaping take the temperature for every 20 seconds for 3 minutes Repeat the process 2 more time record all data HEAT CAPACITY OF THE REACTION measure 50 ml of HCL in a Styrofoam cup take the temperature measure out 50ml of NaOH take the temperature mix the solution up add another Styrofoam cup to keep the heat from escaping take the temperature for every 20 seconds for 3 minutes Repeat the process 3 more time record all data do the same for NH4Cl and NaOH, and HCL and NH3 a) b) Tmix = 55.46 c) Taverage =53.794 d) (!00)(4.18)(55.46 – 53.794)= 693.88 e) f) -(100 x 4.18 x 11.575) + (20.61 x 11.575)= -45990.785J NaOH+HCl -(100 x 4.18 x 1.22) + (20.61 x 1.22)= -484.82J NH4Cl and NaOH -(103 x 4.18 x 10.17) + (11 x 10.17)= -4490J HCl and NH3 g)-46kj/mole -4.85kj/mole -44.9kj/mole h) NaOH + HCl –&gt; NaCl+Cl2O OH + H–&gt; H2O NH4Cl + NaOH –&gt; NH3 + H2O NH4 + OH –&gt; NH3 + H2O NH3 + HCl –&gt; NH4Cl NH3 + H –&gt;NH4 i) (-46-4.85)= -41.15 j) (22.7-44)/44) x 100 = -48% yield What is calorimetry? Experimental determination of heat change in chemical process How does the graphical temperature analysis improve accuracy of your data? It allows the determination of the inteneous theritocil temperature of the mixing temperature What is the