Experiment 25 Lap Report Sheet PDF

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Summary

Experiment 25 Lap Report Sheet. This is the report sheet for the Lab....

Description

Experiment 25 Report Sheet Calorimetry Date __________ Lab Sec. ______ Name ____________________________________________ Desk No. __________ A. Specific Heat of a Metal Unknown No. _______________

Trial 1

Trial 2

50 g

50.9 g

1. Mass of metal (g)

_______________

_______________

2. Temperature of metal (boiling water) (°C)

_______________

90.1

90.5 _______________

3. Mass of calorimeter (g)

51 g _______________

_______________

4. Mass of calorimeter + water (g)

_______________

_______________

100 g

100 g

50.6 g

151 g

5. Mass of water (g)

150.6 g

6. Temperature of water in calorimeter (°C)

25 _______________

7. Maximum temperature of metal and water from graph (°C)

_______________

28.5 _______________

8. Instructor’s approval of graph

_______________

_______________

28.3

25.8 _______________

Calculations for Specific Heat of a Metal 3.3

1. Temperature change of water, ∆T (°C) 2. Heat gained by water (J)

1379.4 J

1128.6 J

-61.8

3. Temperature change of metal, ∆T (°C) 4. Specific heat of metal, equation 25.5 (J/g •°C)

2.7

0.4464 J/g

5. Average specific heat of metal (J/g •°C)

-62

*

0.3576 J/g

0.402 J/g

Data Analysis, B

*Show calculations for Trial 1 using the correct number of significant figures.

Experiment 25

301

Specific Heat of a Metal Trial 1

Trial 2

Enthalpy (Heat) of Solution for the Dissolution of a Salt

Enthalpy (Heat) of Neutralization for an Acid–Base Reaction Trial 1

Trial 2

Trial 1

Trial 2

Trial 1

Trial 2

Time Temp Time Temp Time Temp Time Temp Time Temp Time Temp Time Temp Time Tem

Laboratory Questions Circle the questions that have been assigned. 1. Part A.1. The 200-mm test tube also contained some water (besides the metal) that was subsequently added to the calorimeter (in Part A.4). Considering a higher specific heat for water, will the temperature change in the calorimeter be higher, lower, or unaffected by this technique error? Explain. Lower because a bigger mass means higher heat required to heat it causing a lower change in temp.

2. Part A.5. In measuring the specific heat of a metal, Josh used the highest measured temperature for calculating the metal’s specific heat rather then the extrapolated temperature. Will this decision result in a higher or lower specific Because the relationship between temperature and specific heat is inverse, heat value for the metal? Explain. when the temp goes up the specific heat will be lower.

3. Part B. The enthalpy of neutralization for all strong acid–strong base reactions should be the same within experimental error. Explain. Will that also be the case for all weak acid–strong base reactions? Explain. 4. Part B. Heat is lost to the Styrofoam calorimeter. Assuming a 6.22C º temperature change for the reaction of HCl(aq) with NaOH(aq), calculate the heat loss to the inner 2.35-g Styrofoam cup. The specific heat of Styrofoam is 1.34 J/g• ºC. 5. Part B.3. Jacob carelessly added only 40.0 mL (instead of the recommended 50.0 mL) of 1.1 M HCl to the 50.0 mL of 1.0 M NaOH. Explain the consequence of the error. 6. Part B.3. The chemist used a thermometer that was miscalibrated by a plus 2ºC over the entire thermometer scale. Will this factory error cause the reported energy of neutralization, ∆Hn, to be higher, lower, or unaffected? Explain. 7. Part C.3. If some of the salt remains adhered to the weighing paper (and therefore is not transferred to the calorimeter), will the enthalpy of solution for the salt be reported too high or too low? Explain. 8. Part C. The dissolution of ammonium nitrate, NH4NO3, in water is an endothermic process. Since the calorimeter is not a perfect insulator, will the enthalpy of solution, ∆Hs, for ammonium nitrate be reported as too high or too low if this heat change is ignored? Explain.

304

Calorimetry...