This document is a formal lab report for Experiment 25, focusing on calorimetry in a chemistry lab setting. It details the methods used to measure enthalpy and specific heat capacity of various substances using a calorimeter. The report includes quantitative measurements, such as the specific heat of Metal A, and the enthalpy changes associated with acid-base reactions and the dissolution of ammonium nitrate. Key results are presented, including average specific heat values and heat changes for different trials. The document is structured with sections for the abstract, specific heat calculations, enthalpy of solution, and a discussion of findings. It is intended for educational purposes, likely aimed at students in a chemistry course. The report provides a comprehensive overview of calorimetry principles and experimental results.
FORMAL LAB REPORT: EXPERIMENT 25
CALORIMETRY
Subject: Chemistry Lab
Date: April 16, 2026
Abstract
The main purpose of the Calorimetry experiment is to measure the
enthalpy and specific heat capacity of substances using a calorimeter.
Physical reactions involve the transfer of heat, which can be released as an
exothermic reaction or absorbed as an endothermic reaction. Major results
for the three quantitative measurements include the average heat energy
(ΔT) within the substances. Metal A yielded an average specific heat of
55.81 J/g °C. The acid-base reaction, an exothermic process producing
heat and H2O, resulted in an average ΔT of 2487.1 J (2.4871 kJ/mol H2O).
The dissolution of salt (Ammonium Nitrate) measured the energy evolved
or absorbed, resulting in an average ΔH of 12098 J/mol of salt.
1. Specific Heat of Metal A
The specific heat of a metal is the energy required to change one gram of the unknown
metal by 1°C.
Average Specific Heat (Metal A): 55.81 J/g °C
2. Enthalpy of Solution: Dissolution of Salt (Ammonium Nitrate)
This procedure measures the energy change (lattice energy and hydration energy) when
Ammonium Nitrate dissolves in water.
Measurement Trial 1 Trial 2
Mass of Salt 5.447 g 5.275 g
Moles of Salt 0.068 mol 0.066 mol
•
Measurement Trial 1 Trial 2
Mass of Calorimeter 33.904 g 33.815 g
Mass of Calorimeter + Water 53.865 g 53.873 g
Mass of Water (m
water
)
19.96 g 20.06 g
Initial Temperature (T
i
)
21.4 °C 21.4 °C
Final Temperature (T
f
)
29.3 °C 29.6 °C
Calculations for Enthalpy (Heat) of Solution
Calculation Trial 1 Trial 2
Temperature Change (ΔT) 9.34 °C 9.54 °C
Heat Change of Water (q
w
)
779.3 J 799.9 J
Heat Change of Salt (q
s
)
16.14 J 15.95 J
Total Enthalpy Change (q
total
)
795.4 J 815.85 J
ΔH
soln
11942.5 J/mol 12254.8 J/mol
Average ΔH
soln
: 12098.7 J/mol of salt
Discussion
In this experiment, we measured the average amount of heat energy expressed across
three procedures. The findings are summarized by the following calculation models:
Specific Heat of Metal: Calculated using the relation between the specific heat of the
calorimeter and the temperature change.
Specific Heat = (22.7 * 19.795 * 19.5 °C) / (23.497 *
77.5 °C) = 56.12 J/g °C
Enthalpy of Neutralization (Acid-Base): Using the combined masses and the specific
heat of water (4.18 J/g°C).
ΔH = Specific Heat
H2O
* Combined Masses * ΔT
ΔH = 4.18 * 100 * 6.2 = 2591.6 J (2.5916 kJ)
Dissolution of Ammonium Nitrate: The calculation accounted for the heat change of
water and the heat change of the salt per mole.
ΔH = [(-4.18 * 19.96 * 7.9) + (-1.74 * 5.447 * 16.14)] /
0.068 = 11942.5 J/mol
End of Document
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