Lab 10

Lab 10
To demonstrate how to measure the energy changes
associated with various neutralization reactions, and
how to measure the heat capacity of a calorimeter.
Acids and Bases
 Acid: donates H+ ions to the aqueous solution in
which it is dissolved
 Base: donates OH- ions to the aqueous solution or
accepts H+ ions from the aqueous solution in which
it is dissolved
 Strong acid: dissociates completely in aqueous
 Strong base: dissociates completely in aqueous
Neutralization Reactions
 Strong acids and strong bases react to produce a salt
and water; a solution with an overall pH of 7 under
ideal conditions (neutralization reaction):
HCl(aq) + KOH(aq)  KCl(aq) + H2O(l) + heat
 Neutralization reactions are exothermic, thus liberating
heat to the surroundings.
 Calorimeters measure the heat associated with a
chemical reaction.
 We have to account for the heat transferred from the
solution to the calorimeter so we can add it back in.
 For this reason we perform a calibration on the
calorimeter prior to running the experiment on the
acid / base reaction.
 Heat (q) is the transfer of energy between two
objects; always from hot to cold. The amount of heat
transferred depends on the mass of the object.
 Temperature reflects the random motion of particles
in an object and is independent of mass.
 You will be working with both heat and temperature
 Calibrate your thermistor.
 Hot water bath
 Room temperature water bath
 Ice water bath
 Calibrate your calorimeter to find CCAL.
 Room temperature water
 Hot water
 Determine the energy transfer involved with your
neutralization reaction.
 Strong acid
 Strong base
Safety Concerns
 Reagents:
 HNO3 (1 N) / HCl (0.2 N)
 NaOH / KOH
 Eye Contact:
 Irritating, burns, permanent eye damage, tearing, redness, pain,
impaired vision, blindness
 Skin Contact:
 Irritating, redness, pain, soreness, severe skin burns, ulcers,
stains, destruction, scaling, and blistering
 Inhalation:
 Breathing difficulties, pneumonia, pulmonary edema, coughing,
choking, irritation of nose, throat, and respiratory tract, burns,
and death
 Ingestion:
 Pain and burns of the mouth, throat, esophagus and
gastrointestinal tract. Corrosive to mucous membranes,
perforation of the esophagus and stomach, abdominal pain,
nausea, vomiting, abnormal sensations of hands and feet, and
general gastro-intestinal upset.
 Dispose waste in the appropriate waste receptacles.
• Acidic and basic solutions / waste need to be disposed
in the acid/base waste container in the fume hood.
• Solutions with a pH between 6 and 8 can be disposed
down the drain.
Lab 11 Reminder
 Lab 11 is next.