Introduction to Specific Heat Capacities

Name:________________________ Per:_____ Worksheet- Introduction to Specific Heat Capacities Heating substances in the sun: The following table shows the temperature after 10.0 g of 4 different substances have been in direct sunlight for up to 60 minutes. Time (minutes) Air (° C) Water (° C) Sand (° C) Metal (° C) O (initial) 15.0 min 30.0 min 45.0 min 60.0 min 25°C 28.9°C 32.5°C 36.2°C 40°C 25°C 26.2°C 27.5°C 28.8°C 30°C 25°C 30°C 35°C 40°C 45°C 25°C 35°C 45°C 55°C 65°C Step 1: Create a line graph for each substance on graph below. Label the substances. Step 2: Answer questions 1. Order the substances based on the time required to heat them from : slowest fastest 2. Which do you think will cool the fastest? Explain 3. When you boil water in a pot on the stove, which heats faster, the metal or the water? Explain. 4. Why do you think different substances heat up and cool down at different rates? ***Specific heat capacity = the amount of heat needed to raise the temperature of 1 g of a substance by 1 degree. *** 5. Based on the definition above, which of the 4 substances do you think has: a) the highest specific heat capacity? b) the lowest heat capacity? 6. Here are the heat capacities of the four substances: 4.18 J/g °c, 1.00 J/g °c, 0.80 J/g °c, & 0.60 J/g °c. Match & then label each substance with its specific heat capacity on the graph. 7. If something has a high specific heat capacity will it take a lot of heat or a little heat to change its temperature? Explain. (careful! Use the definition, your graph, and the data from #6) 8. Assuming they both start at the same temperature, which will heat up faster, a swimming pool or a bath tub? Explain your thinking. Worksheet- Calculations involving Specific Heat 1. For q= m ●c ● Δ T : identify each variables by name & the units associated with it. 2. Heat is not the same as temperature, yet they are related. Explain how they differ from each other. a. Perform calculations using: (q= m ●c ● Δ T) 1. Gold has a specific heat of 0.129 J/(g×°C). How many joules of heat energy are required to raise the temperature of 15 grams of gold from 22 °C to 85 °C? b. Determine if it’s endothermic or exothermic 2. An unknown substance with a mass of 100 grams absorbs 1000 J while undergoing a temperature increase of 15 °C. What is the specific heat of the substance? Endothermic or exothermic?_______________ Endothermic or exothermic?_______________ 3. If the temperature of 34.4 g of ethanol increases from 25 °C to 78.8 °C, how much heat has been absorbed by the ethanol? The specific heat of ethanol is 2.44 J/(g×°C) 4. Graphite has a specific heat of 0.709 J/(g×°C). If a 25 gram piece of graphite is cooled from 35 °C to 18 °C, how much energy was lost by the graphite? Endothermic or exothermic?_______________ Endothermic or exothermic?_______________ 5. Copper has a specific heat of 0.385 J/(g×°C). A piece of copper absorbs 5000 J of energy and undergoes a temperature change from 100 °C to 200 °C. What is the mass of the piece of copper? 6. 45 grams of an unknown substance undergoes a temperature increase of 38 °C after absorbing 4172.4 Joules. What is the specific heat of the substance? Look at the table on page 513 of your book, and identify the substance. Endothermic or exothermic?_______________ Endothermic or exothermic?_______________ 7. A 40 g sample of water absorbs 500 Joules of energy. How much did the water temperature change? The specific heat of water (liquid) is 4.18 J/(g×°C). 8. If 335 g of water at 65.5 °C loses 9750 J of heat, what is the final temperature of the water? Liquid water has a specific heat of 4.18 J/(g×°C). 2.Endothermic or exothermic?_______________ Endothermic or exothermic?_______________