Chemistry Final Exam Practice Questions
1
Ice is used to cool a glass of warm water. Initially, the glass is filled with 500.mL
of water at 33C. 297g of ice are added to this water. The mixture is then
stirred until thermal equilibrium is reached. Find the final temperature of this
mixture, and the amount of ice remaining (if any).
2
Acetic acid (CH3COOH) is produced in the liquid form by the combination
reaction of gaseous methanol (CH3OH) with carbon monoxide.
Write a balanced equation for this reaction.
Calculate the enthalpy of reaction based on the following standard enthalpies.
CH 3OH : H f ° = -201kJ / mol
a)
b)
CO : H f ° = -110.5kJ / mol
c)
CH 3COOH : H f ° = -484kJ / mol
Estimate the enthalpy of reaction using the following bond energies in kJ/mol.
Compare this value to that value found in (b).
C-H
C -C
C -O
C=O *
CºO
O- H
413
347
358
745
1072
467
*Value for C=O is valid only for the CO2 molecule, but may be used as an
approximation here.
3
a)
b)
c)
4
a)
b)
c)
d)
Write the abbreviated electron configurations for each atom or ion, and indicate if
it diamagnetic or paramagnetic.
N
d)
Sc
Mg
e)
ClXe
f)
C+
Write a molecular orbital diagram for each pair. Indicate the bond order, and if a
bond will form. Also indicate if the molecule is diamagnetic or paramagnetic.
CNNO
NO+
Na2
5
a)
Which one of the following pairs would have a higher ionization energy? Explain.
Kr or Ar
b)
C or F
c)
Na+ or He
6
A 1.25x10-3g sample of a protein is dissolved in water to total volume of 1.00mL.
The osmotic pressure of this solution is measured to be 2.04mmHg. Calculate
the molar mass of this protein.
7
Calculate the mass of ethylene glycol (C2H6O2) mixed in 10.0L of water needed
to produce an antifreeze solution with a freezing point of -20.0C. The freezing
point depression constant for water is 1.86 C-kg/mol.
8
a)
Draw resonance structures for the following molecules.
NO3
b)
O3
c)
N3-
9
Draw resonance structures for each molecule. Use formal charge to predict the
most stable.
N2O (three resonance structures; nitrogen is central atom)
XeO3 (eight resonance structures)
a)
b)
10
a)
Draw Lewis structures for each compound, minimizing formal charge. Then
predict the molecular structure.
POCl3
b)
ClF3
c)
SCl2
d)
PH3
11
Provide the set of quantum numbers corresponding to an electron in a 5d orbital.
12
An electron emission spectral line for Be3+ appears at 253.4nm. If the excited
state was at the n = 5 level, calculate the principle quantum number of the lower
energy level.