Chemistry



Heat calculations practiceQ = m x c x ?t Q = m x ?Hfus Q = m x ?Hvap1 cal = 4.18 J5513830164995-mmetal x cmetal x Δtmetal = mwater x cwater x ΔtwaterSubstanceSpecific Heat J/(g.oC)SubstanceSpecific Heat J/(g.oC)Aluminum (s)0.90Mercury (s)0.14Calcium (s)0.65Silver (s)0.24Copper (s)0.39Water (s)2.03Gold (s)0.13Water(l)4.18Iron (s)0.46Water (g)2.011. What is the total number of joules released when a 5.5 gram of liquid water at 17oC is cooled to 5oC? (endothermic/exothermic)2. What is the total number of heat energy, in calories, absorbed by 25 grams Ca(s) when the temperature increases from 24oC to 30oC? (endothermic/exothermic)3. In a household radiator, 1000 g of steam at 100oC condenses (changes from gas to liquid). How much heat in joules is released? 4. An 18 g piece of an unidentified metal was heated from 21.5oC to 89oC. If 292J of heat energy was absorbed by the metal in the heating process, what is the identity of the metal? 5. What is the identity of a piece of substance if 586.96 g of the that substance absorbs 6.75×103 joules of heat, and its temperature changes from 32°C to 57°C.6. What mass in grams of aluminum will change its temperature from 4oC to 7oC when 5.25 x 102 J of heat is added to it? (endothermic/exothermic)7. How much heat in calories is absorbed when 20 grams of ice melts at 0oC to water? (endo/exo)8. A 178.26 g piece of an unidentified metal was heated from 35.5oC to 70oC. If 8.61x102 J of heat energy was absorbed by the metal in the heating process, what is the identity of the metal? 9. A 5.5 g of Copper was heated from 25oC to 30oC. How much energy, in calories was absorbed by the copper? (endothermic/ exothermic) 10. A 45 g piece of an unidentified substance was heated from 120.5oC to 140oC. If 1809J of heat energy was absorbed by the substance in the heating process, what is the identity of the substance? 11. A 150 grams of H20 (g) was decreased from 130oC to 110oC. How much heat, in calories did the H2O (g) release? (endothermic/exothermic)12. What is the mass of gold if 55 joules was needed to heat the sample from 15oC to 70oC? 13. How much heat in calories is absorbed when 150.grams of liquid water vaporize to steam at 100oC?14. What is the amount of heat energy required to change 15.5 grams of ice at -20.5oC to water at 45oC? How much heat (in kJ) is absorbed when 36 g H2O(l) at 100oC is converted to steam at 100oC? Water vapor (10 g) is cooled from 110oC to 100oC at which time it is condensed to liquid water. How much energy, in joules, is released? A 36 g piece of ice at -20oC is heated to 0oC and melted. How much is absorbed, in kilojoules? How many kilojoules of heat are required to melt 18 g popsicle at 0oC? Assume the popsicle has the same molar mass and heat of fusion as water. A 5 g sample of an unknown substance is heated from 25oC to 55oC, requiring 135 J to do so. What is the specific heat of the substance? What substance is this?A 150 g sample of a metal at 75oC is added to 150 g of H2O at 15oC. The temperature of the H2O rises to 18.3oC. Calculate the specific heat of the metal if all the heat lost by the metal is gained by the H2O.A 10 g sample of metal pellets are heated to 100oC. The hot pellets are then dropped into 97.3 g of water at 22oC. Calculate the specific heat of the metal if the final temperature is 23.7oC. A 110 g sample of copper is heated to 82.4oC and then placed in a container of water at 22.3oC. The final temperature of the water and copper is 24.9oC. What is the mass of the water in the container, assuming that all the heat lost by the copper is gained by the water? Find the specific heat of aluminum if it takes 630 calories of heat to raise the temperature of 97.5 grams of aluminum by 30°C?How many Joules of heat will be released when 6 grams of H2O(l) at 40°C changes to H2O(s) at 0°C? How many grams of liquid water at 100°C can be vaporized by 9000 Joules of energy? Calculate the specific heat of 94.2 g of unknown metal if it takes 3250 Joules to increase the temp by 750C.How many joules of energy are required to raise the temperature of 20 g of water from 00C to 1000C? (No phase change occurs)How many joules of energy are required to change 15 g of ice at 00C to vapor at 1000C?Calculate the specific heat of 50 g of a metal that decreases from 1000C to 410C when 850 J were released.Calculate the heat of fusion when a substance with a mass of 25 g freezes while releasing 825 J of energy.217 J were released by 62.5 g of a metal when temp decreased by 80C. Calculate the specific heat of the metal. How many calories were absorbed by 25 g of water melting at 00C? How many calories are released when 10 g water cools from 980C to 10C? What is the temperature change of 40 g of aluminum when it releases 1250 joules of energy? ................
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