# AP Assignment 2-4: DUE TUESDAY NOVEMBER 19, 2013 Name

```AP Assignment 2-4: DUE TUESDAY NOVEMBER 19, 2013
Name ______________________________________________________________________ Period _____________
1. Palmitic acid, CH3(CH2)14COOH, is an example of a fatty acid found in the body. The heat of combustion (∆Hcomb) of
palmitic acid is -9977 kJ/mol.
a. Given 100.0 g of palmitic acid, how much heat is produced when it is combusted?
b. Using the standard heat of formation of H2O (l), how many moles of hydrogen gas are required to react with oxygen
gas to produce the amount of energy calculated in (a). (Hint: stoichiometry between H2O (l) and H2 (g).)
H2(g) + &frac12; O2(g) → H2O (l)
∆Hf&deg; = -285.8 kJ/mol
c. What volume of hydrogen gas is required?
d. How many molecules of hydrogen gas are required?
2. A 3.15 g sample of potassium chloride contains chlorine-35 and chlorine-37. The abundance of Cl-35 is 75.771%. This
sample is reacted with excess aqueous silver nitrate to produce a precipitate with an 85.5% yield.
a. Write the balanced molecular and net ionic reactions.
b. What mass of precipitate is formed?
c. What is the mass of the Cl-35 atoms in the precipitate?
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