Heat of Solution in Water of Lithium Chloride, Potassium Chloride - Lab | SOC 1004, Lab Reports of Introduction to Sociology

Download Heat of Solution in Water of Lithium Chloride, Potassium Chloride - Lab | SOC 1004 and more Lab Reports Introduction to Sociology in PDF only on Docsity! Date Performed: 2/4/08 Name: Lakesia Harrington Date Submitted: 2/11/08 Partner: Larmara Perry Instructor: Jessica Evans Heat of Solution Objective  To determine and interpret the heats of solutions in water of lithium chloride, potassium chloride, and calcium chloride.  To illustrate an application of Hess’ Law. Experimental Data Water=100mL=100g LiCl=1.18g KCl=2.07g CaCl2= 3.09g Temperature of H20 (initially) =22.61⁰C Temperature of H20 LiCl= 24.39⁰C Temperature of H20 (initially) =21.37⁰C Temperature of H20 KCl=20.29⁰C Temperature of H20 (initially) =24.75⁰C Temperature of H20 CaCl2=28.52⁰C Sample Calculations LiCl q=(m1 +m2)Csoln (T2-T1) =(1.18g+100g)(4.100 x 10-3)(24.89-22.61) =(101.18)(4.100 x 10-3)(2.28) qsurrounding=0.94583064 qsalt=-0.94583064 kJ/mol ∆Hsoln= -0.94583064 x 42.39 =-33.977641= -34 kJ/mol 1.18 ∆Hsoln -34 kJ/mol ∆ H lattice - +852 kJ/mol ∆Hhydration -887 kJ/mol Results and Conclusions Salt ∆Hlattice (kJ/mol) ∆Hsoln (kJ/mol) ∆Hhydration (kJ/mol) Csoln (kJ g-1 deg-1) LiCl +853 -34 -887 4.100 x 10-3 NaCl +786 +3.9 -782 4.092 x 10-3 KCl +715 +16 -699 4.038 x 10-3 CaCl2 +2258 -42 -2300 4.125 x 10-3 LiCl and H20 is an exothermic reaction as well as CaCl2 and H20 since their value for qsalt are negative and qsurrounding are positive. The value for LiCl for qsurrounding is + 0.94583064 and qsalt for LiCl is - .94583064 which give lets us know that ∆Hsoln is exothermic. NaCl and H20 and KCl and H20 is an endothermic reaction since their values for qsalt are positive and values for qsurrounding are negative. The value for KCl for qsalt is +0.04451313528 and the value fro qsurrounding is - 0.04451313528. this lets us know that ∆Hsoln is endothermic. Ionic radii and charge are the two factors that affect ∆Hsoln. The smaller ionic radii then the bigger the hydration energy. The ionic radii for Lithium (Li) is 76. The ionic radii for Sodium is (Na) 102. The ionic radii for Potassium (K) is 138 and the ionic radii fro chloride is 181. Since lithium ha steh smaller ionis radii that is why it lies the lowest on the graph. Hcnagr als o has a role in ∆Hsoln, since Lithium, Sodium, and Potassium have the same charge of +1 then they all lie on the same line on the graph. Calcium, however, has a charge of +2. Since Calcium has a different charge from the others, calcium lies on the graph by itself. Discussion of Experimental Uncertainty There were some forms of experimental uncertainty. There could have been human error regarding the temperature of the water and salt. Measuring the salt could also lead to experimental error. However the results were pretty much precise. Answers to Definitions a. Hess’ Law- For any reaction that can be written in steps, the enthalpy is the same as the sum of the enthalpy values for the steps. b. heat of solution- the amount of heat absorbed or released when one mole of ionic compound is dissolved in enough water to produce a solution of infinite dilution