Presentation on theme: "The candle lab: calculations Data: 0.95 g, 30.6 °C 1. q = heat/energy change, units: J or Joules c = specific heat, units: J/g°C m = mass, units: g or."— Presentation transcript:
The candle lab: calculations Data: 0.95 g, 30.6 °C 1. q = heat/energy change, units: J or Joules c = specific heat, units: J/g°C m = mass, units: g or grams T= temperature change, units: °C 2. 200 g 3. q = cm T = 4.18 J/g°C x 200 g x 30.6 °C = 25 582 J or 25.6 kJ
4. 25.581 kJ/0.95 g wax = 26.9 kJ = 27 kJ 5. First, assume the heat absorbed by the water is equal to the heat released by the candle 1 mol C 25 H 52 = 352 g or 352.52 #mol= 0.95 gx 1 mol / 353 g= 0.00269 mol kJ/mol = 25.581 kJ / 0.00269 mol = 9 510 kJ/mol = 9.5 x 10 6 J/mol 6. Calorimeter: An apparatus used in the determination of the heat of a reaction Calorimetry: The science of measuring the quantities of heat that are involved in a chemical or physical change.
7. The calorimeter is made up of more than just water (the metal from the can) Other sources of error include anything that interferes with the transfer of heat or the measurement of that heat. E.g. incomplete transfer of heat, loss of heat, evaporation of water, incomplete combustion. Not:experimental error, inaccurate thermometer For more lessons, visit www.chalkbored.com www.chalkbored.com