Chemistry Mentor Sample Quiz Packet (S2017)

Chemistry Mentor Quiz Topics:

Lewis Structure, Formal Charge, & Resonance Structures

Organic Nomenclature and Isomers

Gas Laws and Stoichiometry

The following are sample questions similar to the quiz problems you might encounter.

The quiz problems might contain multiple topics such as “limiting reagent with

thermochemistry” or “limiting reagent with gas laws”.

Bring a scientific calculator for the quiz; however, the reference table/formula sheet at the end of

this document will be provided.

Please solve the problems in easy-to-understand steps. Make sure to explain the reasoning

behind each step.

Sample Question One – Lewis Structure, Formal Charge, & Resonance Structures:

Assign formal charges to all the atoms in the following Lewis structure of hydrazoic acid HN3.

Suggest a lower-energy resonance structure for the molecule and explain why it is more stable

than the one shown above.

Sample Question Two – Organic Nomenclature:

Write the condensed or bond-line structures of the following compounds.

a) 2,2-dimethyloctane

b) 1,3-dimethylcyclopentane

c) 1,1-diethylcyclohexane

d) 6-ethyl-5-isopropyl-7-methyloct-1-ene

e) cis-pent-2-ene

Chemistry Mentor Sample Quiz Packet (S2017)

Sample Question Three – Gas Laws:

A sample of an unknown gas with a mass of 3.620 g was made to decompose into 2.172 g of O2

and 1.448 g of S. Before the decomposition, this sample occupied a volume of 1120 mL at 75

cm Hg and 25.0 °C. What is the molecular formula of this gas?

Sample Quiz Solutions Fall 2017

Sample Question One – Lewis Structure, Formal Charge, & Resonance Structures:

Assign formal charges to all the atoms in the following Lewis structure of hydrazoic acid HN3.

Suggest a lower-energy resonance structure for the molecule and explain why it is more stable

than the one shown above.

Solutions:

The second structure shown few number of formal charges and smaller magnitude of formal

charges. However, the overall charge of the molecule is the same (zero).

Sample Quiz Solutions Fall 2017

Sample Question Two – Organic Nomenclature:

Write the condensed or bond-line structures of the following compounds.

a) 2,2-dimethyloctane

b) 1,3-dimethylcyclopentane

c) 1,1-diethylcyclohexane

d) 6-ethyl-5-isopropyl-7-methyloct-1-ene

e) cis-pent-2-ene

Solutions:

Sample Quiz Solutions Fall 2017

Sample Question Three – Gas Laws:

A sample of an unknown gas with a mass of 3.620 g was made to decompose into 2.172 g of O2

and 1.448 g of S. Before the decomposition, this sample occupied a volume of 1120 mL at 75

cm Hg and 25.0 °C. What is the molecular formula of this gas?

Solutions:

Chemistry I Reference Tables and Formula

Chemistry Mentor Quiz Spring 2017

NA = 6.022 × 1023 R = 8.314 J·mol–1·K–1 or R = 0.08206 L·atm·mol–1·K–1

1 atm = 760 mmHg = 760 torr = 1.01325 bar = 1.01325 × 105 Pa = 14.7 psi = 29.92 in Hg

PV = nRT PA = χA PTotal RT

PMd

M

RTu

3rms

A

B

A

B

M

M

d

d

B

A

)(rateeffusion

)(rateeffusion

nRTnbV

V

anP

)( meas2

2

meas

Boltzmann Constant: kB = R/NA 1 D = 3.34 ×10–30 C • m

me = 9.10939 × 10–31kg c = 2.998 × 108 m/sec h = 6.626 × 10–34 J·s

2

2

2

1

111

nnRH

RH = 1.096776 × 107 m–1

E = hν c = νλ En = – (2.18 × 10–18J) 1/n2 (Hydrogen Atom)

Momentum: p = mu m

pmuKE

22

22

(note u = velocity, ν = frequency)

mu

h

p

h

)(rq C106.1(electron) 19q

KEelectron = hν – Ф or if atom or molecule KEelectron = hν – IE (Ionization Energy)

q = CΔT C = heat capacity = m (specific heat)

ΔE = q + w w = – PΔV H = ΔE + PΔV

C = heat capacity = m (specific heat) = n Cm m = sample mass n = moles of sample

Cm = molar heat capacity

)(reactantsf(products)frxn HnHmH

pH = –log[H+] pOH = –log[OH–] pH + pOH = 14.00

Ka × Kb = Kw Kw = 1.0 × 10–14 (at 25°C) ]HA[

]A][H[a

K

][B

]OH][BH[b

K

nRTKK )(cp

Quadratic equation: ax2 + bx + c = 0 a

acbbx

2

42