Temperature Scales Practice Key

Name: Date: Temperature-Scales The Fahrenheit and Celsius temperature scales are the most commonly used scales for reporting temperature values. Scientists use the Celsius scale almost exclusively, as do many countries of the world . The United States relies on the Fahrenheit scale for reporting temperature information. You can convert informati on reported in degrees Celsius to degrees Fahrenheit or vice versa using conversion formulas. Fahrenheit (° F ) to Celsius (°C) conversion formula: ° C = ( ° F - 32 ) | Celsius (°C) to Fahrenheit (°F) conversion formula: ° F ( h ° c) + 32 = EXAMPLE What is the Celsius value for 65° Fahrenheit? •C = ^ ( 65 ® F - 32 ) ° C = 18.3 • 200°C is the same temperature as what value on the Fahrenheit scale? °F = °F = 392 j( 200°C ) + 32 PRACTICE t 1 . The weatherman reports that today will reach a high of 45° F. Your friend from Sweden asks what the temperature will be in degrees Celsius. What value would you report to your friend? ' 2. 3. 4. 5. 33} Your parents order an oven from England. The temperature dial on the new oven is calibrated in degrees Celsius. If you need to bal e a cake at 3 0° F in the new oven, at what temperature should you set the ^ t — [ 10^ ^ A German automobile's^engine temperature gauge reads in Celsius, not Fahrenheit. The engine temperature should not ris above about 225° F. What is the corresponding Celsius temperature on this car's gauge? ( [ C1: ^ ’ -*f ( J 35 - 3a ) C Your dial? '- grandmother in Ireland sends you her favorite cookie recipe. Her instructions say to bake the cookiesjtf 190.5°C. To whatJahrenheit temperature would you set the oven to bake the cookies? . A scientist iqo . T + 33L wishes to generate ^ a chemical reaction in his laboratory. The ^ J 15°F 5T F F' 15°C L^ 1/ / . . ^^ - \ v F \I 12J3-L temperature values in his laboratory manual are given in degrees Celsius. However, his lab thermometers are calibrated in degrees Fahrenheit. If he needs to heat lusj eactants; to 32°C, what temperature will he need to monitor on his lab thermometers F * 6. You call a friend in Denmark during the Christmas holidays and say that the temperatu re in Boston is 15 degrees. He replies that you must enjoy the warm weather. Explain his comment using your knowledge of the Fahrenheit and Celsius scales. To help you get started, fill in this table. What is 15° F on the Celsius scale? What is 15°C on the Fahrenheit scale? C, / 16 ' - —— , j ' Page 2 of 2 Extension : the Kelvin temperature scale scale. On the Kelvin scale, 0 K For some scientific applications, a third temperature scale is used: the Kelvin zero. Absolute zero is equal to - 273°C, or (degree symbols are not used for Kelvin values ) represents absolute ture values in Celsius, -459° F. When scientists are conducting research, they often obtain or report their tempera , or vice versa . To convert Celsius and other scientists must convert these values into Kelvin for their own use values to their Kelvin equivalents, you would use the formula: = ° C + 273 K EXAMPLE • ture for the Kelvin scale? Water boils at a temperature of 100°C. What would be the corresponding tempera K = ° C + 273 = K • 100° C + 273 = 373 n; subtract 273 from the To convert Kelvin values to Celsius, you would perform the opposite operatio Kelvin value to find the Celsius equivalent. would this substance melt? A substance has a melting point of 625 K. At what Celsius temperature ° C = K - 273 625 K - 273 = °C = 352 Although we rarely need to convert between Kelvin and Fahrenheit, use the K = °F = ^ following formulas to do so: (° F + 460 ) ( rK) - 460 > PRACTICE 2[ this gas boil? A gas has a boiling point of 175°C. At what Kelvin temperature would IT5 X f 213 if someone accidentally broke a 2. A chemist notices some silvery liquid on the floor in her lab. She wonders find out of the silver stuff is mercury thermometer, but did not thoroughly clean up the mess. She decides to point for the liquid is 275 K. really mercury. From her tests with the substance, she finds out that the melting ce mercury? Explain A reference book says that the melting point for mercury is 38.87°C. Is this substan s <9 7 *3 '3 3 your answer and show all relevant calculations. MO J rruri \jbiience qtiiz A ° C - nnP - fbr i/nKJootoh / ^a Science jMuch ; ytfu are asked to outdoor an Camp'in Florida . During 3. It is August 1 st and you are at as 90. Is this identify the temperature scale for a thermometer that reports the current temperature ? Fill in the table below to thermometer calibrated for the Kelvin, Fahrenheit, or Celsius temperature scale answer this question. l. - - ^ * - ' ^ rf - ^ 305 32* C 90° F mf - 90°C -i s y c 90 ' 12 ) Name: Date: Specific Heat Specific heat is defined as the amount of heat energy needed to raise 1 gram of a substanc e 1 °C in temperature. • Specific heat values are used in the heat equation is: Q = T2 - T{ ) where Q is the heat energy (Joules), m is the mass of the substance ( kilograms), Cp is the specific heat of the substance ( J /kg°C ), and ( 7N T / ) is the change in temperature ( °C) • - The higher the specific heat, the more energy is required to cause a change in temperature. Substances with higher specific heats require more loss of heat energy to experience a lowering of their temperature than do substances with a low specific heat. Some sample specific heat values are presented in the table below: Material water ( pure) • Specific Heat ( J/kg °C ) aluminum steel silver oil 4, 184 900 470 235 1 ,900 concrete 880 glass 800 gold wood 129 2,500 Water has the highest specific heat of the listed types of matter. This means that water is slower to heat but is also slower to lose heat. EXAMPLE • How much energy is required to heat 35 grams of gold from 10°C to 50°C? Looking for Solution The heat energy in joules to heat 35 grams of Q n\ ( Tz gold by 40°C. Given Q ( 0 5 kg ) l 29 J ( 50 ° C - 10 ° C) 0 Mass = 35 grams = 0.35 kilogram Q ( 0 5 kg ) l 29 ( 40° C) Specific heat of gold = 129 J/g°C j T2 = 50°C and T = 10°C Q ~ 1,80.6 joules Relationship To produce the necessary change in temperature, 1 ,806 joules of heat energy need to be put into Q m ( r 2 this sample of gold. rp = Cp = , = cp rp ^= ( ^ ] ( —^^ ) ^ Q - y y\ C A T Page 2 of 2 PRACTICE the following heat problems. , Using the heat formula and the table of specific heat values solve 7°C when heat energy is added. How much heat I . A 0.5- kilogram piece of aluminum increases its temperature 6 energy produced this change in temperature? (Q = 2. 3. 4. 5. 6. ^ of this amounLoLwaler was raised by 7°C, A volume of water has a mass of 0.5 kilogram. If the temperature _i [ p< \ ) -!-, I 04) ~\ how much heat energy is produced ? £ . m of steel by 10°C? How much heat energy is required to raise the temperature-oti kilogra 'l = 14100 XI £5 - (. I MjM'iOYlotemperatu re ot 100 liters of water from 10° C to 25°C ? Note: the raise to l needec is energy How much heat ~ - CXI ( 00 J One liter of water has a mass of one kilogram. jj ( ( - - ^ S j op IY) ] j MJ temperature decreases from 45°C to , When 1 ,500 joules of energy is lost from a 0.12-kilogram object the rtfyrrt .ma lr? ( 40°C. WhaUs the specifjc heat of tjus> o ject Of whaU aten HsJhr when A 0.23 Kilogram object increases What is the specific heat of a materiarthat gains 600 joules oi ~ |qg> g in temperate by 3°C? toiHs th mqt rial'^ C POO ^ -^ LoOO S ^ ^ ^ ^ Tix^ - ^ energy ^^ -- ^} - q VT> j energy is added to'it. If the A liquid with a specific heat ofu*>00 J / kg ? has 4, 750 joules of heat ". \ temperature increases from 20°C to 30°C, what is the mass of the liqttKP ' ) ( 1.400 I ,150 S ed e that gains 52,800 joules of energy when its temperature is increas concret of block a of mass 8. What is the ; Vj : )(^yc ) by 5°C? 63 Boo $ ( rs sample of glass from -45°C to 15°C. How 9 . A scientist wants to raise the temperature of a 0.10-kilogram ? much heat energy is required to, produce this change-in -temperature (OO Q* . They pot oftresh water fr<5m 20uClo HRTCin order to boil water for pasta 10. A person wishes to of heat joules need to apply 669,440 calculate that their pot holds 2 kilograms of water and that they would ’ ions correct? Defend your energy to produce the desired temperature change. Are the person s calculat J I answer and demonstrate all relevant calculations J 7. = Tw 4 - Y X o 0 - - ^ * conductor? A conductor is a material that requires very little better the is or steel wood 15. Which substance . heat energy to experience a change in temperature. Explain your answer ^ ^ - — T— MI ^ (A - - ^ ^ £ . orc