Unformatted text preview: SCH4U Unit 3 Malaysia’s National Drink Note . Adapted from Teh Tarik, by Maxilla, (20072015), Daily Burn, Inc. a. What is the specific heat capacity of teh tarik ? Assume that the cup of teh tarik was heated from room temperature to 80.0°C. Given data: Initial Temperature: 25.0 °C Final Temperature: 80.0 °C 35 × 10 1 KJ/cup ÷ 227 g = ΔT= 55.0 °C Mass= 1 cup = 227.0 grams (4.184 KJ )
1 cup
Change in Enthalpy per gram = 1 Kcal × 83 Kcal
1 cup × 227 grams ΔQ= (4.184 KJ ) 1 Kcal ×
ΔQ= m ∙ c ∙ ΔT 2 83 kcal = 3.5 × 10 KJ We want c * ΔQ
m∙ΔT = c 3.5 × 10 2 KJ × 1000 J = 3.5 × 10 5 J 1 KJ
3.5 × 10 5 J ÷ (227.0 g ∙ 55.0 °C) = c c = 28 J /g ∙ c ∴ T he specific h eat capacity of t eh tarik is 28 J /g ∙ c Created by: Ms. Kimberley Gagnon / k [email protected] = 1.5 KJ/g SCH4U Unit 3 b. A student used 0.23 moles of an unknown fuel to heat the cup of teh tarik (mass of mug is145.0 g). The transfer of heat is only 65.3 % efficient. i. What is the unknown fuel? Assume we have a Glass cup ErrorGlass specific heat capacity = 0.84 J/g ∙ c Mass of glass= 145.0 g Q of system= Q of cup + Q t eh tarik = [(145.0g) ∙ (0.84 J/g ∙ c) ∙ (55.0 °C)] + [ 3.5 × 10 2 KJ] =(6.7 KJ)+(3.5 × 10 2 KJ) =3.6 × 10 2 KJ energy output
ef f iciency = energy input× 100% 65.3%
× E nergy input = Energy output  0.655 × E nergy input = Energy output 100%
Energy output
2 E nergy input =
0.655  Energy input = 3.6 × 10 KJ ÷ 0.655 Energy input = 5.5 × 10 2 KJ 2 ΔH =− Q  ΔH = 5.5 × 10 KJ ΔH =n ΔHcomb  ΔHn = ΔHx ΔHcomb = 5.5 × 10 2 KJ/0.23mol =2.4 × 10 3 KJ/mol * round to 2219.2 KJ/mol = Propane ∴ the unknown fuel is Propone ii. How many grams of the fuel did the student have to use to heat the cup of teh tarik ? M ass of P ropane U sed moles × M olar mass of C3H8 M ass of P ropane
0.23 mol 44.1 g
= 1.00 mol Used mass of propane= 1.0 × 10 1 g ∴ the student had to used 1.0 × 10 1 g of propane c. How many kilograms of carbon dioxide emissions will be produced from heating this cup of t eh tarik? 5.5 × 10 2 KJ × 66.61 Kg
= 3.7 × 10 4 Kg KJ ∴ 3.7 × 10 4 Kg of carbon dioxide emissions will be produced. Created by: Ms. Kimberley Gagnon / k [email protected] SCH4U Unit 3 Reference A. Clancy, C., Amdemichael, T., Aurora, A., & Anderson, M. (2011). Chemistry 12. Toronto, Ont.: McGrawHill Ryerson. page 290340 B. Cup to Gram Conversions Allrecipes Dish. (2014). Retrieved August 11, 2016, from http://dish.allrecipes.com/cuptogramconversions/ C. Kcal to kilojoules conversion. (n.d.). Retrieved August 11, 2016, from http://www.rapidtables.com/convert/energy/kcaltokj.htm Hint 1: Refer to page 325 and to Table 5.4; round the Heat of Combustion to the same number of significant figures as your answer so you can determine which fuel was used. Hint 2: Refer to Table 5.6 Created by: Ms. Kimberley Gagnon / k [email protected] ...
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 Fall '16
 Biology, Combustion, Tarik, Ms. Kimberley Gagnon, Teh Tarik

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