# expt. no. 2 Calorimetry.pdf - Chem 181 Chemistry for...

• ProfessorDugongPerson694
• 7

This preview shows page 1 - 3 out of 7 pages.

Name Course & Year Date Group Number Section Chem 181 Chemistry for Engineers Laboratory _____________________________________ ______________ ____________________________________ _______________ Experiment No. 2 CALORIMETRY Objectives: 1. To demonstrate ability to simple calorimetry experiment 2.To analyze calorimetry results to calculate the specific heat of unknown metals. Apparatus: 2 - 6 oz. styrofoam cups wire gauze 2 thermometers Bunsen burner 3 test tubes crucible tong 1 - 250mL beaker iron ring 2 - 400 mL beakers cut Styrofoam cup or cardboard cut into 4” squares with a small hole in the middle Materials: unknown pure metal samples that will fit in a 22-mm test tube Theory : Calorimetry is the science of measuring a quantity of heat. Heat is a form of energy associated with the motion of atoms or molecules of a substance. Heat, Q, is measured in energy units such as joules (J) or calories (cal). Temperature, T, is measured in degrees Celsius,°C. Temperature and heat are related to each other by the specific heat, c p , of a substance, defined as the quantity of heat needed to raise the temperature one gram of a substance by one degree Celsius (J/g- ° C). The relationship between quantity of heat (Q), specific heat ( c p ), mass (m) and temperature change (∆T) is mathematically expressed by the equation: T mc Q p or    C C g / J g Joules The amount of heat needed to raise the temperature of 1 g of water by 1 degree Celsius is the basis of the calorie. Thus, the specific heat of water is exactly 1.00 cal/g∙ 0 C. The SI unit
Metal of energy is the joule and it is related to the calorie by: 1 calorie = 4.184 J. Thus, the specific heat of water is also 4.184 J/g∙ 0 C. The specific heat of a substance relates to its capacity to absorb heat energy. The higher the specific heat of a substance the more energy required to change its temperature. In this experiment, calorimetry is used to determine the specific heat of a metal. Heat energy is transferred from a hot metal to water until the metal and the water have reached the same