SCES 3163 PHYSICAL CHEMISTRY (PRACTICAL REPORT)

10.0 Reference

Arrhenius. (2020). Enthalpy Change of Neutralization. Retrieved from

https://chem.libretexts.org/Bookshelves/Physical_and_Theoretical_Chemistry_Textbook_Maps/Su

pplemental_Modules_(Physical_and_Theoretical_Chemistry)/Thermodynamics/Energies_and_Po

tentials/Enthalpy/Enthalpy_Change_of_Neutralization.

Bodner, R. (2021). Energy, Enthalpy, and the First Law of Thermodynamics. Retrieved from
https://chemed.chem.purdue.edu/genchem/topicreview/bp/ch21/chemical.php.

Davis, O. (2020). The Effect of Temperature on Reaction Rates. Retrieved from
https://chem.libretexts.org/Bookshelves/General_Chemistry/Map%3A_General_Chemistry_(Petru
cci_et_al.)/14%3A_Chemical_Kinetics/14.09%3A_The_Effect_of_Temperature_on_Reaction_Rat
es.

Livonia, M. (2022). How to Minimize Measurement Error. Retrieved from
https://www.usalab.com/blog/how-to-minimize-measurement-error/.

Maharashtra, et al. (2022). How is heat loss prevented in a calorimeter? Retrieved from
https://byjus.com/questions/how-is-heat-loss-prevented-in-a-calorimeter/.

Saylordo. (2017). Chemical Thermodynamics. Retrieved from https://saylordotorg.github.io/text_general-
chemistry-principles-patterns-and-applications-v1.0/s22-chemical-thermodynamics.html.

Toppr. (2020). Enthalpy of neutralisation of CH3COOH by NaOH. Retrieved from
https://www.toppr.com/ask/question/enthalpy-of-neutralisation-oftextctexthtext3textcooh-by-naoh-
is-506-kjmol-and-the-heat-of-nuetralisation-of/.

Wirkkla. (2014). Enthalpy of Neutralization. Retrieved from
https://www.ccri.edu/chemistry/courses/chem_1100/wirkkala/labs/Enthalpy_of_Neutralization.pdf.

3.2. Example of task (Ying Sii Mei)

1.0 Topic
Thermochemistry.

2.0 Purpose
To determine the enthalpy change of neutralisation between a strong acid and a strong base.

3.0 Theory
Thermochemistry is the study of chemical reactions and the energy change which involves heat.

In a chemical reaction, reactants and products are considered as the system while everything includes
the vessel in which the reaction takes place, the air or any other material in thermal contact with the
reaction system are the surroundings. According to Schaller (2020), the enthalpy change of a reaction
is the amount of energy lost or gained during the reaction.

Diagram 1
Energy profile diagrams for exothermic and endothermic reactions.
If heat is lost from the system to the surroundings in an exothermic reaction, the enthalpy
change of the reaction, ∆ will have a negative value. Meanwhile, if heat is absorbed from the
surrounding to the system in an endothermic reaction, ∆ will have a positive value. So, the enthalpy
of reaction, ∆ is also the difference between the enthalpy of the products and the enthalpy of the
reactants.

∆ = ∑ − ∑

This experiment aims to determine the enthalpy change of neutralisation between a strong acid
and a strong base. Neutralisation is a reaction when an acid and a base react to form water and salt
(Dunn & Chappell, 2020). In all neutralisation reactions, water is produced as a result of the combination
of hydrogen ions, + of acid and hydroxide ion, − of alkali or base. So, the heat of neutralisation
can be defined based on the formation of water. When one mole of + of acid combined with one mole
of − of alkali to form one mole of water, the heat released is the heat of neutralisation. Neutralisation
reactions are generally exothermic and thus ∆H is negative.

+ → +
+( ) + −( ) → 2 ( ) ∆ =

In this experiment, the formula = ∆ or = ∆ can be used to determine the heat
released or absorbed by the system to determine the enthalpy change of neutralisation between a
strong acid and a strong base. is the mass of the substance, is the specific heat capacity of the
substance, ∆ is the change in temperature of the substance and = is the heat capacity of the
substance (Tan & Sheila, 2019).

4.0 Apparatus and materials
1.0 mol sodium hydroxide, 1.0 mol hydrochloric acid, 1.0 mol nitric acid, 1.0 mol sulfuric acid, beaker,
measuring cylinder, thermometer, filter paper and dropper.

5.0 Procedure

a. 30 cm3 of 1.0 mol sodium hydroxide and 30 cm3 of 1.0 mol hydrochloric acid were prepared in two
cups separately.

b. The initial temperature of the sodium hydroxide and hydrochloric acid was measured using a
thermometer and recorded in a table.

c. The hydrochloric acid was poured into sodium hydroxide slowly and mixed well for approximately
3 minutes.

d. The final temperature was measured using the thermometer and recorded in a table.
e. The experiment was repeated and an average value was obtained.

f. Step a. to step e. was repeated twice by replacing 30 cm3 of 1.0 mol hydrochloric acid with 30 cm3
of 1.0 mol nitric acid and 15 cm3 of 1.0 mol sulfuric acid respectively.

6.0 Observation

Set Chemicals Trial 1 Trial 2

Set 1 1.0 mol NaOH Initial Final Initial Final
Set 2 1.0 mol HCl Temperature Temperature Temperature Temperature
Set 3 1.0 mol NaOH
1.0 mol HNO3 (°C) (°C) (°C) (°C)
1.0 mol NaOH 29.5 33.0 29.0 34.0
1.0 mol H2SO4 29.5 29.0
29.5 34.5 29.0 35.0
29.5 29.0
29.5 37.5 29.0 39.0
29.5 29.0

7.0 Data analysis and interpretation

Set Chemic Trial 1 Trial 2

als

Initial Final Differenc Initial Final Difference Average

Temp Temper e in Temperature Temperat in difference

eratur ature Tempera (°C) ure (°C) Temperat in

e (°C) (°C) ture (°C) ure (°C) temperatur

e (°C)

Set 1.0 mol 29.5 33.0 3.5 29.0 34.0 5 4.25

1 NaOH

1.0 mol 29.5 29.0

HCl

Set 1.0 mol 29.5 34.5 5 29.0 35.0 6 5.5

2 NaOH

1.0 mol 29.5 29.0

HNO3

Set 1.0 mol 29.5 37.5 8 29.0 39.0 10 9.0
3 NaOH 29.0

1.0 mol 29.5
H2SO4

Calculation of the enthalpy of neutralisation between a strong acid and a strong base.

Set 1: Sodium hydroxide and hydrochloric acid.

( ) + ( ) → ( ) + 2 ( )

ℎ = ∆
= (30 + 30) × 4.2 × 4.25

= 1071

30
= = 1000 × 1

= 0.03

= 0.03

= 1071 × 10−3
0.03

= 35.7 −1

∴ ℎ ℎ = −35.7 −1

Set 2: Sodium hydroxide and nitric acid.

( ) + 3( ) → 3( ) + 2 ( )

ℎ = ∆
= (30 + 30) × 4.2 × 5.5

= 1386

30
= 3 = 1000 × 1

= 0.03

= 0.03

= 1386 × 10−3
0.03

= 46.2 −1

∴ ℎ ℎ = −46.2 −1

Set 3: Sodium hydroxide and sulphuric acid.

11
( ) + 2 2 4( ) → 2 2 4( ) + 2 ( )

ℎ = ∆
= (30 + 15) × 4.2 × 9.0

= 1701

30
= 1000 × 1

= 0.03

15
2 4 = 1000 × 1

= 0.015

= 0.03

= 1701 × 10−3
0.03

= 56.7 −1

∴ ℎ ℎ = −56.7 −1

The enthalpy of neutralisation between a strong acid and a strong base.

Chemical equation ∆ ( −1)

( ) + ( ) → ( ) + 2 ( ) −35.7

( ) + 3( ) → 3( ) + 2 ( ) −46.2
11 −56.7

( ) + 2 2 4( ) → 2 2 4( ) + 2 ( )

8.0 Discussion

a. Why is the temperature of the initial solution of acid and alkali measured
after 5 minutes?

b. How to improve the practical procedure to obtain a more accurate value
of the heat of neutralisation.

c. Compare the value of the heat of neutralisation between a strong acid
and a strong base obtained with the actual value from theory
(reference). Give an explanation.

d. Give inference of the value of heat of neutralisation between ethanoic
acid and sodium hydroxide. Give justification.

The above questions a, b, c and d will be further discuss in this experiment on the enthalpy
change of neutralisation between a strong acid and a strong base. At first, the temperature of the initial
solution of acid and alkali will be measured. The temperature of the initial solution of acid and alkali
should be measured after 5 minutes so that the temperature of the initial solution of acid and alkali is
even. As shown in the observation table of this experiment, the temperature of the initial solution of
acid and alkali obtained are even with the temperature 29.5 ℃.

In this experiment, it is found that lots of improvements can still be done to improve the practical
procedure so that a more accurate value of heat of neutralisation or the enthalpy of neutralisation can
be obtained. For example, strong acid should be poured to the strong alkali quickly and carefully so
that less heat will lost to the surrounding. The mixed solution should also be stirred continuosly so that

the temperature of the solution is even. Lastly, the thermometer reading should also be constantly
observed so that the highest reading of temperature achieved by the mixed solution can be taken.

The standard value of the heat of neutralisation between a strong acid and a strong base are
always very closely similar with values between −57 −1 and −58 −1 (Clark, 2020).

However, the heat of neutralisation or the enthalpy of neutralisation obtained in this experiment is

different or does not fall in the range of the standard value of the heat of neutralisation between a strong

acid and a strong base which is in between −57 −1 and −58 −1. The heat of neutralisation

obtained in this experiment for ( ) + ( ), ( ) + 3( ) and ( ) +

1 2 4( ) are −35.7 −1, −46.2 −1 and −56.7 −1 respectively. There are actually
2

three possible factors which will affect the heat of neutralisation. The three factors are quantity of acid

and alkali, basicity of the acid and strength of acid and alkali. All of the acid and alkali used in this

experiment are strong acid and alkali. The quantity of acid and alkali as well as the basicity of the acid

also does not affect the heat of neutralisation in this experiment. A monobasic acid has one removable

hydrogen ion, dibasic acid has two removable hydrogen ions and tribasic acid has three removable

hydrogen ions. A complete neutralisation of a strong dibasic acid with an alkali

produces double amount of heat as compared to a strong monobasic acid. Although there are

monobasic ( ( ) and 3( ) ) as well as dibasic acid ( 2 4 ) used, the standard heat of
neutralisation for the reaction between dibasic acid with strong alkali will still should be nearly the same

with the reaction of monobasic acid with strong alkali because the quantity of dibasic acid used is half

the 30 3 monobasic acid which means that the heat of neutralisation by dibasic acid will also be half

and equal to the heat of neutralisation by the monobasic acids in this experiment. Since the three

factors stated will not be the reason of the difference of heat of neutralisation obtained in this experiment

compared to the standard heat of neutralisation, the reason that will be affecting the difference of heat

of neutralisation obtained in this experiment compared to the standard heat of neutralisation will be

because of the heat of neutralisation is not measured at standard condition which should be 25 ℃ and

1 atm in order to obtain the standard value of the heat of neutralisation between a strong acid and a
strong base which is in between −57 −1 and −58 −1.

The experiment has far been discussing about the heat of neutralisation between strong acid
and strong alkali. So, what if the strong acid is changed with weak acid such as ethanoic acid. The
value of heat of neutralisation between ethanoic acid and sodium hydroxide will be lesser than the heat
of neutralisation between strong acid and strong alkali. This is because ethanoic acid is a weak acid
that dissociates partially in water and most of the ethanoic acid still exists as molecules when it

dissolves in water. Some of the heat given out during the neutralisation is used to dissociate the acid
completely in water, thus the heat given out will be lesser.

9.0 Conclusion

The heat of neutralisation obtained in this experiment for ( ) + ( ), ( ) +

3( ) and ( ) + 1 2 4( ) are −35.7 −1, −46.2 −1 and −56.7 −1
2

respectively. The difference of heat of neutralisation obtained in this experiment compared to the

standard heat of neutralisation which is in between −57 −1 and −58 −1 is because the

heat of neutralisation is not measured at standard condition which should be 25 ℃ and 1 atm.

10.0 Reference

Clark, J. (2020, August 16). Enthalpy Change of Neutralization. LibreTexts. Retrieved from
https://chem.libretexts.org/Bookshelves/Physical_and_Theoretical_Chemistry_Textbook_
Maps/Supplemental_Modules_(Physical_and_Theoretical_Chemistry)/Thermodynamics/E
nergies_and_Potentials/Enthalpy/Enthalpy_Change_of_Neutralization

Dunn, K. & Chappell C. (2020, August 16). Neutralization. LibreTexts. Retrieved from
https://chem.libretexts.org/Bookshelves/Physical_and_Theoretical_Chemistry_Textbook_
Maps/Supplemental_Modules_(Physical_and_Theoretical_Chemistry)/Acids_and_Bases/
Acid_Base_Reactions/Neutralization

Schaller, C. P. (2020, August 16). Enthalpy Changes in Reactions. LibreTexts. Retrieved from
https://chem.libretexts.org/Bookshelves/Physical_and_Theoretical_Chemistry_Textbook_
Maps/Supplemental_Modules_(Physical_and_Theoretical_Chemistry)/Thermodynamics/F
undamentals_of_Thermodynamics/Enthalpy_Changes_in_Reactions#:~:text=The%20heat
%20that%20passes%20into,whether%20a%20reaction%20can%20happen.

Tan, Y. T. & Sheila Shamuganathan. (2019). Thermochemistry. (5th ed.), Chemistry for
Matriculation Semester 2 Fifth Edition Updated (pp. 41-64). Selangor Darul Ehsan: Oxford
Fajar.

11.0 Appendix

Diagram 2 Diagram 3
30 3 30

Diagram 4
29.5 °C is the initial temperature of 1.0 mol sodium hydroxide, 1.0 mol hydrochloric acid, 1.0 mol nitric acid
and 1.0 mol sulfuric acid.

Diagram 5 Diagram 6
3 + +

34.5 ℃ 33 ℃

Diagram 7
2 4 +

37.5 ℃