1. -1 points OSGenChem1 5.1.WA 00 A piece of aluminum with a mass of 4.01 grams

Question

1. -1 points OSGenChem1 5.1.WA 00 A piece of aluminum with a mass of 4.01 grams is heated to raise its temperature from 23.1°C to 207.6°C My Notes O Ask Your T (a) What quantity of heat (in joules) is absorbed by the aluminum? (b) Determine the molar heat capacity of aluminum J/mol-K Supporting Materials Periodic Table Constants and Factors Supplemental Data Additional Materials section 5.1 Tutorial 2. -11 points OSGenChem1 5.1.WA 008 My Notes Ask Your Te Two friends, Pamela and Elaine, compared snack items they planned to enjoy during a work break. Pamela's snack was a small bag of shortbread cookies composed of 2.4 grams fat, 18 grams carbohydrates, and 2.2 grams protein. Elaine hada bag of popcorn composed of 2.9 grams fat, 29 grams carbohydrates, and 3.8 grams protein. Nutrient Fuel value (kJ/g) Carbohydrate Fat Protein 17 38 17 (a) Using the fuel values provided, calculate the number of calories in each person's snack Pamela's snack Elaine's snack Cal Cal (b) Suppose the friends took a 15-minute walk after snacking. If Pamela burned 43 calories and Elaine expended 49 calories, who had the smaller net gain of calories after snacking and walking? Select Supporting Materials

Explanation / Answer

1)

a)Heat absorbed by ALuminium = mass x specific heat x delta T

= 4.01g x 0.9J/g.C x (207.6-23.1)

= 665.86J

b) molar heat capacity of Aluminium = specific heat x molar mass

= 0.9J/g.C x 27g/mol

= 24.3J/mol.C

2) a ) energy in Pamelas snack = 2.4gx 38 +18x17 + 2.2x17 kJ/g

= 434.6kJ

wekNow 1 calorie = 4.184 J or

1 Cal = 1 kilocal = 4.184kJ

Thus

energy in Pamelas snack = 103.87 Cal

energy in Elaine's snack = 2.9x38 + 29x17 +3.8x17

= 667.6 kJ

= 667.6/4.184 =159.56 Cal

b) Pamela burnt 43 and Elaine burnt 49 Cal on walking. Thus the energy gain for Elaine is greater as she consumed more Cal.

#) 2.09 g of CH3Oh on burning produces 41.61 kJ of heat

one mole = 32g of CH3OH on burning procduce = 32g/mol x 41.61kJ / 2.09 g

= 637.09kJ/mol

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