Temper- ature Specific Heat LabHeatPotpourri Final

100 Temperature Convert a temperature of  C to Kelvins Answer Answer

Temp 100 K =  C K = = Answer = 39.9K

200 Temperature Convert a temperature of  C to  F Answer Answer

Temp 200  F = 1.8  C + 32  F = 1.8  (-15.8) + 32 = 3.56 Answer = 3.6  F

300 Temperature Convert a temperature of 105  F to Celsius Answer Answer

Temp 300  C = (  F – 32) / 1.8  C = (105 – 32) / 1.8 =  C Answer = 41  C

400 Temperature Give the definition of temperature. Answer Answer

Temperature 400 Answer Temperature is the average kinetic energy of all particles in a sample.

500 Temperature Explain what is meant by absolute zero, what is theorized to occur at this temperature, what are the advantages of the Kelvin scale. Answer

Temperature 500 Answer Absolute zero is the lowest theoretical temperature. At absolute zero, atomic motion and volume approach zero. The Kelvin scale is used in scientific calculations because it has no negative numbers. Its  T is also equal to  T in Celsius.

100 Specific Heat Define specific heat and give the SI units for specific heat. Answer Answer

Specific Heat 100 Answer Specific heat is the amount of energy required to raise the temperature of 1 g of a substance by 1 o C. SI Units are: Joules or Joules g o C g K

Specific Heat 200 Answer Gold will heat to 200 o C first because it has the lowest C p and therefore requires less energy to increase its temperature.

200 Specific Heat The C p values of Gold, Mercury and Lead are 0.129, 0.14, and J/g  C respectively. Equal masses of the three metals are placed in an oven at a temperature of 200.  C. Which metal will reach 200.  C first? Explain. Answer

300 Specific Heat Determine the mass of a substance if it has a C p of J/g  C and it absorbs 345 calories when heated from 23.5  C to 99.9  C. Answer Answer

Specific Heat 300 First convert q to Joules ?J = 345 cal x 4.184J = J cal Mass = q = J Cp x  T (0.385J/g o C) ( o C) Answer: Mass = 49.1 g

400 Specific Heat Calculate the specific heat of a substance if 44.4g of it releases cal when cooling from 99.0  C to 23.5  C. Report answer in SI units Answer Answer

Specific Heat 400 Answer Cp = q= cal mass x  T (44.4 g) ( o C) = cal x J = 9.80 J cal g  C

500 Specific Heat Calculate the specific heat of a metal, in SI units, given the following data for a metal that is heated in a hot water bath then poured into a calorimeter containing g of water. Mass of metal =12.55 g Temp of water bath = 98.7  C Ti of water in calorimeter = 26.5  C Tf of water in calorimeter = 32.8  C Answer Answer

Sp Heat 500 Answer q H2O = J/g  C x 35.00g x (32.8  C  C ) = J -q H2O = q metal C p = J = (12.55g) x (32.8  C  C ) Answer = 1.1 J/g  C

100 Lab Apart from type of material, name the 2 criteria that determine the amount of heat energy in a material. Answer Answer

Lab 100 Answer Mass Temperature

200 Lab Explain why a candle goes out when a jar is placed over it. Answer

Lab 200 CO 2 produced from combustion extinguishes the flame by pushing the oxygen away from the wick.

300 Lab The Cp of silver is cal/g o C. What is this specific heat in J/g o C? Answer Answer

Lab 300 Answer ? J= cal x J = goCgoCgoCgoC1 cal Answer = J/g o C

400 Lab What is visual evidence that a gas is being produced in a chemical change? Describe a lab test that would determine if the gas produced is O 2 or CO 2. Answer Answer

Lab 400 Answer Fizzing and bubbling indicates production of a gas. A glowing wood splint inserted into the bubbles will relight if the gas is O 2 and will extinguish if the gas is CO 2.

500 Lab What is the white solid seen on the evaporating dish in Pt 3 of the fuels lab? (hint – it is the product of the initial reaction between chalk and vinegar) Answer Answer

Lab 500 Calcium acetate – it becomes visible when some of the water from the aqueous solution begins to evaporate.

100 Heat What happens to heat in an exothermic change? Describe a chemical change that is exothermic. Answer Answer

Heat 100 Answer releasesAn exothermic change releases heat energy. Combustion is an exothermic chemical change. Zn + HCl to produce H 2 gas, Zn pyrotechnics, KClO3 + sugar are also exothermic chemical changes.

200 Heat Define the term “Heat”. Answer Answer

Heat 200 Answer Heat is energy that is transferred between samples due to a difference in temperatures.

300 Heat Define “calorie” Answer Answer

Heat 300 Answer A calorie is the amount of heat required to raise the temperature of 1 g of water by 1 degree Celsius

400 Heat Six boneless chicken tenders (deep fried) contain joules of energy. Convert to calories and to Food Calories. Answer Answer

Heat 400 ? cal = Joules x 1 cal = Joules Answer = x 10 5 cal ? Food Cal = x 10 5 cal x 1 Food Cal = Food Cal 1000 cal

500 Heat Determine the heat absorbed by g of pure iron if it is heated from 25.0  C to  C. The C p of Fe is 0.444J/g  C. Answer Answer

Heat 500 Q = sp ht x mass x  T Q = J/g  C x g x (255.5  C  C ) Q = 1540 J

100 Potpourri Define BTU Answer Answer

Potpourri 100 BTU: The amount of heat required to raise the temperature of one pound of water by 1 o F.

200 Potpourri Name the following phase changes and tell whether they are exothermic or endothermic solid to gas liquid to solid gas to liquid AnswersAnswers

Answers for Potpourri 200 solid to gas– sublimation, endo liquid to solid – freezing, exo gas to liquid – condensing, exo

300 Potpourri Explain, in terms of heat, phase change and molecular motion, why sweating cools you off. Answer Answer

Potpourri 300 Sweat evaporates from your skin. Evaporation is an endothermic process because the molecules must gain energy to speed up and break free of their attraction to each other in order to go from liquid phase to gas phase. The energy that the molecules absorb is taken from your skin. When the molecules evaporate to the gas phase and leave your skin surface, they take this absorbed energy away. Your skin has lost energy thus is cooler.

400 Potpourri g of water must absorb 3138 J of energy as it heats from 25 o C to 100 o C g of water needs 22,600 J of energy to go from liquid to gas at 100 o C. Explain. Answer Answer

Potpourri 400 A phase change from liquid to gas requires a much greater amount of energy than a simple temperature change. As temp increases yet phase remains same, molecules are speeding up As water goes from a liquid to a gas, its molecules must have enough energy to become very spread apart, overcoming the attractions between molecules

500 Potpourri g of water ice must be vaporized (solid-liquid-gas) The heat of fusion of water is 333J/g. The heat of vaporization is 2260 J/g. What is the total energy to vaporize this water? (hint- it will need to go from 0 o C to 100 o C) Answer Answer

Potpourri 500 Answer To melt the ice = 333J/g x g = 8330 J To heat liquid water from 0 to 100 o C is 4.184J/g o C x g x 100 o C =10460J To vaporize = 2260J/g x g =56500J Sum = ~ J

Final Jeopardy Convert a ΔT of 10.0 o F to a ΔT in o C. Answer

Final Jeopardy Answer ΔT of 10.0 o F ÷ 1.8 = ΔT of 5.6 o C