Heat of Solution
Objectives:
This experiment aimed to determine the heat of the solution of different ionic compounds using water as a solvent and to establish whether the dissolving procedure results in exothermic or endothermic reactions.
Introduction/Overview/Background
The heat of the salt solution in water may be measured by dissolving a specific amount of the salt in a specific amount of water and noting the temperature change with a thermometer. The temperature change can measure the heat of the solution. When the mark q is given, the chemical and physical changes include heat release or absorption. The absorption of heat implies that the variation is endothermic and is marked using a positive mark. Heat release implies that the change is exothermic and is marked using a negative mark. Therefore, for endothermic reactions, it’s (q>0) and (q<0) for exothermic. When the pressure in the system is constant, the heat flow is equal to the total heat.
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Materials used:
Goggles and apron
Distilled water
Thermometer
Stirring rod
CaCl2, NAOH, KOH
MgSO4
Graduated cylinder
Foam cup as a calorimeter
Balance
NH4CL,NH4NO
CH3CO2Na,NaHCO3,NH4NO3
Procedure:
- Measure 100.0 ml of distilled water at room temperature and pour it into the plastic foam cup. Record the temperature of the water in the data table to the nearest 0.1
- Measure a mass of 8-10 grams of calcium chloride using the laboratory balance on paper. Record the mass to the nearest 0.01g.
- Shake the NH4CL from the paper into the water and stir slowly with the stirring rod until the solid dissolves.
- Ensure that the bulb of the thermometer is completely immersed in the liquid. If the temperature increases, record the highest temperature reached. If the temperature reduces, record the lowest temperature reached.
- Please remove the solution by pouring it down the drain, rinse the cup, and return it and the thermometer to the lab bench.
- Repeated steps 2-5 using calcium chloride
Results and Discussion:
Solute
|
Solute mass
(g) |
Mass of water
(g) |
Mass of solution
(g) |
Initial
T(C) |
Final T | rxn/mol | Exothermic/
Endothermic |
NH4NO3
Trial 1 |
7.549 | 100g | 107.549 | 21.7 | 16.3 | 25.768 | endothermic |
Trial 2 | 8.066 | 100g | 107.066 | 21.2 | 15.4 | 26.019 | endothermic |
Trial 3 | 7.949 | 100g | 107.949 | 21.4 | 15.5 | 26.8 | endothermic |
Average ∆Hrxn/mol=+26.20 literature value=+25.7
% ERROR=2% |
|||||||
CaCl2
Trial 1 |
7.279 | 100g | 107.279 | 21.5 | 30.6 | -62.265 | exothermic |
Trial 2 | 8.051 | 100g | 108.051 | 21.6 | 32.2 | -66.06 | exothermic |
Trial 3 | 8.018 | 100g | 108.018 | 21.4 | 31.5 | -63.2 | exothermic |
Average ∆Hrxn/mol=-63.84 literature value=-81.3
% ERROR=22% |
|||||||
NaOH
Trial 1 |
7.9499 | 100g | 107.9499 | 21.5 | 39.8 | -41.597 | exothermic |
Trail 2 | 8.074 | 100g | 108.074 | 21.5 | 41.0 | -41.9 | exothermic |
Trial 3 | 7.577 | 100g | 107.377 | 21.5 | 38.7 | -42.2 | exothermic |
Average ∆Hrxn/mol=-41.90 literature value=-44.3
% ERROR=5.4% |
|||||||
NaHCO3
Trail 1 |
8.8932 | 100g | 107.9499 | 21.7 | 17.4 | 18.499 | endothermic |
Trail 2 | 8.057 | 100g | 108.074 | 21.3 | 17.5 | 22.59 | endothermic |
Trail 3 | 8.323 | 100g | 107.323 | 21.4 | 17.6 | 17.4 | endothermic |
Average ∆Hrxn/mol=+19.50 literature value=+16.7
ERROR=16.8% |
- Calculate the change in temperature T=Tfinal – Tinitial
- NH4NO3
Trial 1
- 3-21.7=-5.4
Trial 2
- 4-21.2=-5.8
Trial 3
- 5-21.4=-5.9
- CaCl2
Trial 1
- 6-21.5=9.1
Trial 2
- 2-21.6=10.6
Trial 3
- 5-21.4=10.1
- NaOH
Trial 1
- 8-21.5=18.3
Trial 2
- 2-21.6=10.6
Trial 3
- 5-21.4=10.1
- NaHCO3
Trial 1
- 4-21.7=-4.3
Trial 2
- 5-21.3=-3.8
Trial 3
- 6-21.4=-3.8
- Percentage error
% error=100%
NH4NO3
1.9%
CaCl2
22%
NaOH
=5.4%
NaHCO3
=16.8%
The table above shows the data obtained from the experiment. The first part shows the heat of the solution of water and NH4NO3. This run had a temperature gain, which meant the reaction was endothermic. There was temperature loss in the heat of the solution of water and CaCl2, implying an exothermic reaction. There was a temperature loss in the heat of the solution of water and NaOH, implying an exothermic. Lastly, there was a temperature gain in the heat of the solution of water and NaHCO3, which meant an endothermic reaction. The percent error for the exothermic reaction was a large value because the temperature was reduced, and heat was lost. The percent error for the endothermic reaction was a small value because the temperature was raised, and the heat was gained.
Conclusions:
This experiment aimed to determine if the solution heat for several compounds was exothermic or endothermic. Each experimental setup was run for three different trials. From the experimental results, the reaction between water and NH4NO3 was endothermic, water and CaCl2 were exothermic, water and NaOH were exothermic, and water and NaHCO3 were endothermic. The experiment also aimed to determine the percentage error for each reaction. There was a considerable percent error for the three trials of the exothermic reactions, whereas there was a small percent error for the three trials of the endothermic reactions.
References:
Chen, D., Yang, H., Yi, Z., Xiong, H., Zhang, L., Zhu, S., & Cheng, G. (2018). C8N26H4: an environmentally friendly primary explosive with high heat of formation. Angewandte Chemie, 130(8), 210
Lozano, E. M., Pedersen, T. H., & Rosendahl, L. A. (2019). Modeling of thermochemically liquefied biomass products and heat of formation for process energy assessment. Applied Energy, 254, 113654.3-2106
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Question
Lab Report
Heat of solution
This lab report must be done in Word; please include all data I have attached and follow the sample lab layout also attached. Please show all calculations and formulas and include graphs.