Heat of Neutralization
Heat of Neutralization
The purpose of this lab was to:
* Determine the heat of neutralization for the reaction of sodium hydroxide (NaOH) and hydrochloric acid (HCI).
The heat of neutralization (∆Hneutzn ) is the heat transferred when 1 mol of an acid reacts with 1 mol of a base. This heat is generally reported in either kilojoules per mole (kJ/mol) or kilocalories per mole (kcal mol). The reaction of HCI and NaOH solutions is shown in Equation 1.
HCI(aq) + NaOH(aq) H20(l) + NaCI(aq) (Eq. 1)
The heat of neutralization for a reaction cannot be measured directly. However, the heat transferred during a neutralization reaction can be calculated from laboratory data.
Glassware: (2) 150-mL beaker, graduated cylinder, glass rod, (2) thermometer Equipment : Ring stand, double thermometer clamp, polystyrene cup Chemicals: 2M hydrochloric acid, 2M sodium hydroxide.
In this experiment, you will determine the temperature change (∆T) for a neutralization reaction as follows.
In the laboratory, you will measure time-temperature data at alternate 30-s intervals over a 5-min period for measured volumes of NaOH solution and of HCI solution. After you mix the two solutions, you will collect time-temperature data at 5.5 min and then at 1-min intervals over a 15-min period for the mixture. From time-temperature graphs of these data, you will find AT. You will plot the temperature in degrees Celsius on the ordinate (y-axis). You will plot the time in minutes on the abscissa (x-axis). Use of an interrupted temperature axis is a convenient way to plot such data.
After the data is plotted, you will draw a vertical line, perpendicular to the x-axis through the point on the x-axis that represents the time of mixing. Next you will draw the best straight line through the plotted points for the temperature of each of the reactants. You will extrapolate these lines so they intersect the line of mixing. The points where these lines intersect the line of mixing are the initial temperatures of the reactants. To calculate the temperature change, you will average the two initial temperatures of the reactants and use that value as the initial temperature (Tinitial) of the reactants. You will then draw the best straight line representing the plotted points for the temperature of the reaction mixture. Extend this line to intersect the line of mixing. This intersection point is the final temperature (Tfinal) of the reaction mixture.
You will determine ∆T for the reaction by subtracting the initial temperature from the final temperature. From ∆T and the volumes and molarities of the reactants, along with some literature data, you will calculate ∆Hneutzn in kj/mol for the reaction of HCI solution and NaOH solution
See attached Sheets
We observed the heat of neutralization for the reaction of sodium hydroxide (NaOH) and hydrochloric acid (HCI). Heat is transferred from the system (the reaction mixture) to the environment in this reaction. Because the heat is lost from the system, the heat change of the system is negative. Therefore, this ∆Hneutralization should be negative. Therefore a minus sign must be places in front of the calculated results kilojoules. And can be better calculated in a more insulated system.
University/College: University of Chicago
Type of paper: Thesis/Dissertation Chapter
Date: 11 January 2017
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