Lab Report. Objectives 1. To determine the enthalpy of neutralization of strong acid and strong base. 2. To determine the quantity and direction of the heat transfer in the dilution of a salt.

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SKU3023 : Chemistry IIEXPERIMENT 3

EXPERIMENT 3 : Enthalpy

3.1 Objectives

. To determine the enthalpy of neutralization of strong acid and strong base.

2. To determine the quantity and direction of the heat transfer in the dilution of a salt.

3.2 Introduction

A chemical or physical change involves heat (energy) is known as Thermochemistry. While reaction that release energy (heat) is called exothermic reaction, and the reaction that absorbs energy from its surroundings is called endothermic reaction. Calorimeter is a device uses to measure a quantity of heat transferred in the Thermochemistry reaction, which undergoes chemical or physical change. The heat transferred in a chemical reaction is defined quantitatively as an enthalpy (heat) of the reaction, at a constant pressure. The is negative if the reactions are exothermic and positive for endothermic reactions. The specific heat of a substance is known as the amount of heat required to raise its temperature for of one gram substance.

The unit of specific heat is .

The enthalpy of neutralization involves acid base reaction and for strong acid and base, the reaction is exothermic. is determined by

a) Assuming the density and specific heat for acid and base solution are the same as water

b) Measure the temperature change,

The unit of is kJ/mol of acid and base reacted. Mass (g) of solution is the total mass of acid and base in solution.

The enthalpy of solution is produced when a salt dissolve in water. Energy is absorbs and releases. KI dissolves in water :

The lattice energy (enthalpy) of salt, and hydration energy (enthalpy), will determined whether heat is absorbed or released when 1 mole of salt dissolve in water. The enthalpy of solution and dilution; is total of and . Salt dispersion enthalpy, is determined experimentally with the combination of heat loss from the salt and water whenever both of them are mixed.

3.3 Chemicals

.0 M HCl solution

.0 M NaOH solution

.0 M HNO3 solution


3.4 Apparatus

Styrofoam cup with lid with a tiny hole for thermometer


Measuring cylinder

00 ml beaker

3.5 Procedures

PART A : Heat of Neutralization of Acid-Base

. 50.0 ml of 1.0 M HCl is measured using measuring cylinder and its initial temperature is recorded.

2. 50.0 ml of 1.0 M NaOH solution is measured and poured into a dry Styrofoam cup and its initial temperature is recorded. The molar concentration of the used is record exactly.

3. Acid is added quickly to the base in the Styrofoam cup. During this period, the cup must be covered properly to prevent any lost of the heat. The cup is stirred carefully and the temperature is recorded for every 10 – 20 seconds until reach to a constant temperature changing.
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4. A graph for vs time (s) and the maximum temperature is determined for the neutralization reaction.

5. The experiment is repeated for more accurate data.

6. By using the same procedure, the experiment procedure is repeated for reaction of NaOH and HNO3. The for the reaction is calculated and the result is compared with the first the neutralization reaction (NaOH + HCl).

PART B : Heat of Salt Solution

1. 5.0 g of prepared NaCl salt is weighed.

2. The mass of a dry Styrofoam cup is measured and the data is ...

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