Week 2 Text exercise-Part I

# 5 c what is its final temperature density of aluminum

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32.5 °C, what is its final temperature? (density of aluminum = 2.70 g/cm 3 ) Answer: mass = density*Volume =2.70*98.5 =265.95 g Al caloric capacity c =0.91 J/(g*Kelvin) m*c*(Tf-Ti) = Q Tf-Ti = Q/(m*c) =67.4/(265.95*0.91) Tf -Ti = 0.278 degree Tf = 32.5+0.278 =32.778 degree Celsius Exercise 72 in Ch. 4 Answer: 72. Fill in the blanks to complete the following table. Chemical Symbol Group Number Group Name Metal or Nonmetal 7A Halogen gases 2A Alkali metal 8A Noble gases 1A Alkali metal 7A Halogen gases Exercise 78 in Ch. 5 Calculate the formula mass for each of the following compounds. Answer: CS 2 = 12.01 + (32.065*2)= 76.14 g/mol C 6 H 12 O 6 = (12.011*6)+(1.0079*12)+(15.999*6) = 180.15 g/mol Fe(NO 3 ) 3 = (55.8452)+( 14.00672*3)+( 15.99943*9) = 241.86 g/mol C 7 H 16 = (12.01078*7)+( 1.007947*16) = 100.20 g/mol

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Exercise 78 in Ch. 6 Calculate the mass percent composition of carbon in each the following carbon compounds. Answer: C 2 H 2 = C=12.01*2 and H=1.008*2 C=92.26% and H=7.74% C 3 H 6 = C=12.01*3 and H=1.008*6 C=85.63% and H=14.37% C 2 H 6 = C=12.01*2 and H=1.008*6 C=79.89 and H= 20.11% C 2 H 6 O= C=12.01*2 and H=1.008*6 and O=15.99 C=52.14% and H=13.13% and O=34.73% Exercise 82 in Ch. 7 A beaker of nitric acid is neutralized with calcium hydroxide. Write a balanced molecular equation and a net ionic equation for this reaction. Answer: 2HNO3 + Ca(OH)2 is 2H2O + Ca(NO3)2 is the balanced molecular equation H+ + OH- is H2O is the net ionic equation Exercise 82 in Ch. 8 Many home barbecues are fueled with propane gas (C 3 H 8 ). How much carbon dioxide in kilograms is produced upon the complete combustion of 18.9 L of propane (approximate contents of one 5-gal tank)? Assume that the density of the liquid propane in the tank is 0.621 g/mL. ( Hint: Begin by writing a balanced equation for the combustion reaction.) Answer: The balanced equation is C3H8 + 5O2 -----> 3CO2 + 4H2O The mass of propane in 18.9L=0.621 x 18.9 = 11.737kg=11737g The amount of propane = mass/molar mass =11737/44=266.75mol The amount of CO2 produced =3 x 266.75=800.25mol The mass of CO2 = 800.25 x 44=35211g or 35.21 kg Submit the assignment, as directed by your facilitator.

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