Enthalpy of Hydration- help with this whole lab 1. Read MISC 327, Graphical Repr

Question

Enthalpy of Hydration- help with this whole lab 1. Read MISC 327, Graphical Representation oft Data, in this series or another authoritative source forsodium acetate dissolved, using Equation 6. a discussion of graphing techniques (4) Calculate the number of moles of anhydrous 2. Why is it necessary for you to wash your hands thoroughly with soap or detergent betore leaving the (5) CalculateHsoudion for anhydrous so- dium acetate in kJ mol , using Equation 7 1707 m 4. In a second experiment, 16.00 g of sodium ace- 3. The following time-temperature data were col. tate trihydrate (GMM- 136.08 g mo) was dissolved lected when 14.00 g of anhydrous sodium acetate in 100.00 mL of water. The initial temperature was (GMM-82.03g mol-)was dissolved in 100.00 mL of 25.00 C, and the final temperature was 20.06 c. water. The heat capacity of the reaction mixture was The heat capacity of the reaction mixture was 4.045J 4.045 Jg deg g deg- (1) Calculate AT, using Equation 9 time, min 0.0 0.5 1.5 2.5 3.5 4.5 termp, time, temp, mW? min 7.0 29.30 23.50 23.45 23.49 23.50 23.50 23.50 29.05 (2) Calculate the heat transterred, Q, using 9.0 28.75 Equation 5. 10.0 11.0 28.20 12.0 27.95 13.0 27.65 14.0 27.35 15.0 27.10 28.50 (3) Calculate the number of moles of sodium acetate trihydrate dissolved, using Equation 6 5.5 6.0 28.30 29.00 Prepare a graph by plotting the temperature on the y-axis (the ordinate) and the time on the x-axis (1) (4) Calculate Adissolution for sodium acetate trihydrate in kJ mor, using Equation 7. (the abscissa). (2) Calculate for the process, using Equa- = 29.30-23.50"c : 5.8 (5) acetate(s) to sodium acetate trihydrate(aq). Calculate AHhydration for converting sodium (3) Calculate the heat transferred, Q, using Equation 5 234

Explanation / Answer

2. It is always necessary to wash your hands before leaving the laboratory as any chemical contaminant attached r adhered to your hands must not be consumed with the food or drink that you might ingest after going from the lab. It is necessary to remove the contaminants by washing.

3. (1) dT = (final - initial) temperature

               = 29 - 23.5 = 5.5 oC

(2) m = 100 + 14 = 114 g

Cp = 4.045 J/g.oC

So,

Q = mCpdT

    = 114 x 4.045 x 5.5 = 2536.2 J

(4) mols of sodium acetate = 14/82.03 g/mol

                                            = 0.171 mol

(5) dH(dssolution) = 2536.2/1000 x 0.171 = -14.83 kJ/mol

4. From the given data,

(1) dT = (final - initial) temperature

           = 20.06 - 25 = - 4.94 oC

(2) Q = mCpdT

m = 100 + 16 = 116 g

Cp = 4.045 J/g.oC

So,

Q = 116 x 4.045 x -4.94 = -2318 J

(3) moles of sodium acetate trihydrate dissolved = 16 g/136.08 g/mol = 0.12 mol

(4) dHdissolution = -Q/mols

                            = 2318/0.12 x 1000 = 19.32 kJ/mol

(5) dH(hydration) for sodium acetate to sodium acetate trihydrate

dH(hydration) = 19.32 - (-14.83) = 34.15 kJ/mol

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