Straight line method for determining the units of the answer:
Given 0.1 mole of a gas at 25 C that occupies a volume of 10 cm3 what is its pressure in atm.
n
P  RT
V
2
3
.1 mole 8.314 J (25  273) K 100 cm 
kg
7 kg m K cm

2.5
10
 2.5 10 7 2


3
2
3
3
 m 
10 cm
K
s cm K m
s m
3

P



kg 1 N 
7 N
 2.5 10 7 2 
 2.5 10
m
s m kg 
m2
2
 s 
But a N/m2 is a Pascal (P).


 1 atm 
P  2.5 107 P
 2.5 102 atm
1.01105 P 

1) Balance the following equations
a) C3H8 + O2  CO2 + H2O
b) Fe2O3 + Al  Fe + Al2O3
c) Na2SO3 + HCL  NaCl + SO2 + H2O
d) Mg3N2 + H2O  Mg(OH)2 + NH3
e) Pb + PbO2 + H2SO4  PbSO4 + H2O
2) Calculate the molecular weight of: H2O (18.01), H2SO4 (94.07), CH4 (16.05), NaBF4.(109.80),
P4O10, BrCl, KMnO4
3) Start with 1.2 kg of reactant in problem 2a above and calculate amount of the first product
produced if the reaction goes to completion. (3.6 kg)
4) A solution is made by mixing A and B. Calculate the various concentrations by filling in the
following table:
A
B
Molarity
molality
mole
% wt
% Vol
Moles/ liter
Moles/ kg
fraction
solution
H2O, 100 cc
H2O, 100. cc
solvent
H2, 0.010 gm
ÇH3CH2OH,
100. cc
density of H2O = 1 gm/cc; CH3CH2OH = 0.789 g/cc.
5.010-2
5.010-2
0.00090
0.010
8.5
17.1
.236
44.1
5) A barometer reads 3 ft of Hg what is the pressure?
(density of Hg is 1.36 x 104 kg/m3. g=9.807 m s-2) (1.24  104 kg/m2 =1.22  105 N/m2)
50
6) Add 10 gm CaCl2 to 1 L of water what is freezing point depression? (Kf 1.86 K mol-1 kg). (0.503 K) N.B. CaCl2 is a strong electrolyte and dissociates completely to yield 3 ions (Ca 2+, Cl-, Cl-) for every mole
of CaCl2.
7) What is freezing point of vodka (50% alcohol by volume) ethanol (CH3CH2OH) has a density
of 0.789 gm/cc). The mixture actually starts to freeze at -29 C. Does this agree with your
calculation? (-31 C not quite right why?)
Do the same calculation for 1% alcohol by volume actual freezing point -0.33 C.
8) Calculate moles in 22.4 l of H2 at 25 C and 5 psig. (P = 1 + 5psi/14.7(psi/atm)=1.34 atm,
1.34atm  22.4l
PV  nRT , n 
 1.22moles
l atm
0.082
298K
K mole

9) Calculate the difference between x3 and (x+1)3 for x=100, 10,000, and 1 x 1012? (Hint do it by
algebra first) (3104, 3108, 31024)

10) How do we know Avogadro's number. (Crystal structure and kinetic theory of gases)
11) What are the units of charge and force?
Ze 2
e2
F


say
and
Lewis
say
?
r2
4 0 r 2
13) The Rydberg constant of 13.6 eV. What is it in cm-1 and J?
c, 2.997925 x 108 m s-1 ; h, 6.6262 x 10-34 J s; e, 1.6022 x 10-19 C (Note that 1 eV = 1.6 022 1019
J Why isthe conversion of eV to J just the charge on the electron? and 1 cm-1 =

h  c 10 2  1.602 1023 J )
21) Why does Gray F  

14) When you shine light on a metal you can sometimes get electron to come off of the metal.
The figure below shows the number of electrons observed as you change the frequency of light.
Can you explain why the number of electrons is 0 for frequencies less then and constant above
? Why when you increase the light intensity does the number of electrons observed increase?
Can you write an equation for the energy of the electrons that are emitted in terms of the energy
of the light? Draw a graph of the kinetic energy of the electrons vs frequency of the incident
light.
14) 1) Succinic acid has two ionizable protons and has a formula of (CH2COOH)2
H 2 A  H +  HA pKA1 = 4.16
HA -  H +  A2 pKA2 = 5.61


What is pH is you have an aqueous solution of 1  10-3 M of succinic acid. (pH = 3.598)
What is the pH if you add enough NaOH to this solution so it has 0.4  10-3 M of Na+. (pH 3.98)
What is the pH if you add more NaOH such that it is not 1.2 10-3 M in Na+? (pH = 5.01)