280 ❯ STEP 4. Review the Knowledge You Need to Score High
(a) Complete the Lewis structure below for glycine. If resonance is possible, you only need
to show one resonance form.H H O
H N C C O
H H(b) Determine the formal charge for each non-hydrogen atom.❯ Answers and Explanations
Note that, while organic chemistry is not an AP topic, all the materials in these questions
depend on basic AP chemistry knowledge, which is why this chapter can be valuable.
(a) 2 C 6 H 14 + 19 O 2 → 12 CO 2 + 14 H 2 O
Give yourself 2 points for the answer shown above or for the coefficients 1, 9/2,
6, and 7. Give yourself 1 point if you have one or more, but not all, of the elements
balanced.
(b) (-487 kJ/10.0 g hexane)(86.17 g hexane/mol hexane) = - 4.20 = 103 kJ/mol
Give yourself 2 points for the above set-up and correct answer (this requires a
negative sign in the answer). If the set-up is partially correct, give yourself 1 point.
(c) The ideal gas equation should be rearranged to the form P = nRT/V.Moles = n =
(5.00 g C H)1 mol CH
86.17 g C H12 mol CO(^614) 12 mol C H
614
614
2
614
= 0.3481 mol CO 2
This answer has an extra significant figure. The mole ratio should match the one
given in your balanced equation. You will not be penalized again for an incorrectly
balanced equation.
R = 0.08206 L atm mol-^1 K -^1 (This value is in your test booklet.)
V = 20.0 L
T = 27 °C + 273 = 300 K (In this case, there is no penalty if you forget to use the
Kelvin temperature.)
P = nRT
V
(^) = (0.3481 mol CO)(0.08206 L atmm⋅⋅ol−−⋅K)(300.K)
(20.0 L)
2
11
= 0.429 atm
Give yourself 2 points for the correct set-up and answer. Give yourself 1 point if
you did everything correctly, except the mole ratio or the Kelvin conversion.
(d) You may need to redraw one or more of your answers to match the answers shown
below.
Give yourself 1 point for each correct answer, with a 4-point maximum. There are
no bonus points for additional answers.