Determination of the Enthalpy of Reaction of a Monobasic Acid with Sodium Hydroxide

Title : Expt.1 Determination of the enthalpy (heat) of reaction of a monobasic acid with sodium hydroxide Experiment no : 1 Experiment title : Determination of the enthalpy (heat) of reaction of a monobasic acid with sodium hydroxide Objectives: 1) To understand the enthalpy chemistry. 2) To determine the calorimeter constant. 3) To determine the enthalpy reaction of acid-base reactions. 4) To study the exothermic reaction. Apparatus and Materials : * Dewar flask, stopwatch, thermometer (5 to 50 ˚C, graduated in 1/10 ˚C), * 50 cm3 graduated pipette fitted with a suction bulb, 10 cm3 graduated cylinder, * Conc. sulphuric acid (specific gravity 1.84, 98.5% H2SO4 ), conc. nitric acid, * 1 M sodium hydroxide, 0.1 M hydrochloric acid, methyl orange indicator. Introduction : Enthalpy is a measure of total energy of a thermodynamic system. It includes the internal energy of the system and the product of its volume multiplied by the pressure exerted on it by its surrounding. H = U + p*V Where, H = Enthalpy V = Volume p = Pressure U = Internal Energy The enthalpy is normally measure with S.I. unit of Joule, J , although other units still in use such as Calorie, C and calorie, c. However, we often measure the change in enthalpy, ∆H instead of measuring the enthalpy, H because the total enthalpy cannot be measured directly. Enthalpy change is defined by the following equation : ∆H = HFinal – HInitial ∆H = Enthalpy change HFinal = Enthalpy of the products HInitial = Enthalpy of reactants A positive value for ∆H indicates it is an endothermic reaction which involve energy released as heat into its surrounding, causing the temperature for the surrounding to rise. A negative value for ∆H indicates it is an exothermic reaction which involve energy acquired from its surrounding as heats, causing the surrounding temperature to drop. Change in enthalpy that occurs as a result of chemical reaction is

References: 1. Darrell D. Ebbing & Steven D. Gammon (2009). General Chemistry Ninth Edition. Boston, MA & New York, NY: Houghton Mifflin Company. Chapter 18, page 732. 2. Raymond Chang (2005). Physical Chemistry for the Bioscience. Edwards Brothers, Inc. Chapter 3, page 46 – 47. 3. Hans Kuhn, Horst-Dieter Forsteling & David H. Waldeck (2009). Principles of Physical Chemistry. New Jersey: John Wiley & Sons, Inc. Chapter 17, page 559. Precaution steps 1) We are required to wear gloves and goggle during the experiment. 2) The bottle of the concentrated nitric acid and sulphuric acid has to be closed when not in use and put in the fume hood because the white fumes of the nitric acid or sulphuric acid can be toxic.