THER 368: 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...