Calorimetry Introduction
CALORIMETRY
K.M.J. PECO1
1INSTITUTE OF CHEMISTRY, COLLEGE OF SCIENCE
UNIVERSITY OF THE PHILIPPINES DILIMAN, QUEZON CITY, PHILIPPINES
DATE PERFORMED: JUNE 21, 2013
INSTRUCTOR’S NAME: LISA MARIE S. RAMIREZ
INTRODUCTION
In all chemical processes, heat is either absorbed or released by the chemical system. It can be observed that when sodium hydroxide is reacted with hydrochloric acid, the container containing the chemical reaction becomes warmer compared to when only one of the reactants is in the container. This simple observation can lead to the conclusion that heat is absorbed by the system. The question is, how much heat does the chemical system absorb from the surrounding and how is it measured?
The heat of a reaction can be measured experimentally. When a reaction results to evolution of heat, the calorimeter, a well-insulated device, absorbs the heat produced from the reaction. The opposite happens in an endothermic reaction. The chemical reaction absorbs heat from the calorimeter. Heat and matter does not enter or leave the calorimeter from its surroundings.
In this experiment, several reactions were studied. The first reaction, the reaction of hydrochloric acid to sodium hydroxide, was used to determine the heat capacity (Ccal) of the calorimeter. The net ionic equation of this reaction is H+ + OH- H2O. Ccal is determined using the formula
Ccal = -(ΔHwater * nLR) / ΔT (eq 1) where ΔHwater is the enthalpy change of water. This is equal to -55.81 kJ/mol. nLR is the number of moles of the limiting reactant, and ΔT is the change in temperature associated with the reaction.
The Ccal obtained was later used to determine the experimental values of the enthalpy change of the reactions (ΔHrxn).
Six other reactions were also used to determine its enthalpy change. The reactions are:
Neutralization:
a. Ammonia and hydrochloric acid
(NH3(aq) + H+(aq) NH4+(aq)) b. Sodium hydroxide and acetic acid
( H+(aq) + OH-(aq) H2O(aq)) c.
K.M.J. PECO1
1INSTITUTE OF CHEMISTRY, COLLEGE OF SCIENCE
UNIVERSITY OF THE PHILIPPINES DILIMAN, QUEZON CITY, PHILIPPINES
DATE PERFORMED: JUNE 21, 2013
INSTRUCTOR’S NAME: LISA MARIE S. RAMIREZ
INTRODUCTION
In all chemical processes, heat is either absorbed or released by the chemical system. It can be observed that when sodium hydroxide is reacted with hydrochloric acid, the container containing the chemical reaction becomes warmer compared to when only one of the reactants is in the container. This simple observation can lead to the conclusion that heat is absorbed by the system. The question is, how much heat does the chemical system absorb from the surrounding and how is it measured?
The heat of a reaction can be measured experimentally. When a reaction results to evolution of heat, the calorimeter, a well-insulated device, absorbs the heat produced from the reaction. The opposite happens in an endothermic reaction. The chemical reaction absorbs heat from the calorimeter. Heat and matter does not enter or leave the calorimeter from its surroundings.
In this experiment, several reactions were studied. The first reaction, the reaction of hydrochloric acid to sodium hydroxide, was used to determine the heat capacity (Ccal) of the calorimeter. The net ionic equation of this reaction is H+ + OH- H2O. Ccal is determined using the formula
Ccal = -(ΔHwater * nLR) / ΔT (eq 1) where ΔHwater is the enthalpy change of water. This is equal to -55.81 kJ/mol. nLR is the number of moles of the limiting reactant, and ΔT is the change in temperature associated with the reaction.
The Ccal obtained was later used to determine the experimental values of the enthalpy change of the reactions (ΔHrxn).
Six other reactions were also used to determine its enthalpy change. The reactions are:
Neutralization:
a. Ammonia and hydrochloric acid
(NH3(aq) + H+(aq) NH4+(aq)) b. Sodium hydroxide and acetic acid
( H+(aq) + OH-(aq) H2O(aq)) c.
References: [1] Petrucci, R.H., Herring, F.G., Madura, J.D., Bissonnette, C. General Chemistry: Principles and Modern Applications, 10th edition.Pearson Education South Asia PTE.LTD., Philippines. 2010. [2] Blauch, D.N. Heat Capacity of the Calorimeter. Copyright 2000-2001, 2009. Web. http://www.chm.davidson.edu/vce/calorimetry/heatcapacityofcalorimeter.html Date accessed June 22, 2013. [3] Brucat, P.J. Calorimetry. University of Florida. Web. http://www.chem.ufl.edu/~itl/4411/lectures/lec_9.html Date accessed June 22, 2013. [4] Blauch, D.N. Calorimetry: Heat Capacity. Copyright 2000,2009. Web. http://www.chm.davidson.edu/vce/calorimetry/heatcapacity.html Date accessed June 23, 2013.