CHEMISTRY 121
Review Problems
1. Fill in the blanks with the correct symbols for the elements.
An atom having a half-filled 2p subshell.
An atom having a total of 6 electrons in its n = 3 principal quantum shell.
An atom that has a tendency to form a +2 cation with the same electron configuration
as Ar (at. #18).
The element that forms a monocation that is isoelectronic with Kr
The period 2 element with only one electron is its 2p subshell
The element that forms a dianion that is isoelectronic with Ne
2.
A 1.500 g sample of toluene, C7H8, was combusted in a 10.5 kg bomb calorimeter with a
heat capacity of 45.06 kJ/oC.This combustion caused the temperature of the calorimeter
to rise from 25.00 oC to 26.43 oC.
a.
What was the amount of heat transferred due to this reaction?
b.
How much heat would be transferred if 3.745 g of toluene were reacted?
3.
A compound was known to be composed of C, H, and O only. When a 5.23 mg sample of
this compound was combusted, 7.66 mg of CO2 and 3.14 mg of H2O were obtained.
What is the percentage of oxygen in this compound?
4.
A white powder used in paints, enamels, and ceramics, has the following percentage
composition: Ba 69.6 %; C 6.09 %; O 24.3 %.
a.
Calculate the empirical formula of this compound.
b.
If the molar mass of the compound were 593 g/mol, what would the molecular
formula be for this compound?
5.
In a certain experiment, 29.52 mL of 1.21 M HI were added to 35.00 mL of 0.951 M
KOH in a simple (coffee cup) calorimeter. Prior to addition of the HI, the temperature of
the solutions was 23.50 oC. After the solutions were mixed, the temperature in the
calorimeter rose to 30.40 oC.
a. Determine the heat transfer (q) experienced by the calorimeter for this reaction.
b. Determine the ΔHrxn per mole of HI.
c. Identify whether this reaction is endothermic or exothermic and explain your reasoning.
6.
Calculate ΔH for the reaction
N2O3(g) ÷ NO(g) + NO2(g)
given the following information
7.
N2(g) + 3/2 O2(g) ÷ N2O3(g)
ΔH = 83.7 kJ
N2(g) + O2(g) ÷ 2 NO(g)
ΔH = 180.4 kJ
1/2 N2(g) + O2(g) ÷ NO2(g)
ΔH = 33.2 kJ
Fill in the table for the following covalent compounds.
Molecule
CO32PCl3
XeCl4
CCl4
3-Dimensional
Picture of the Shape
of the Molecule and
Lewis Structure Name of that Shape
Polar/Nonpolar
Hybridization of
Central Atom
8.
The anticancer drug cisplatin, Pt(NH3)2Cl2, can be produced as shown below.
K2PtCl4 + 2 NH3 ÷ Pt(NH3)2Cl2 + 2 KCl
A student started a reaction with 50.0 g K2PtCl4 and 2.50 g NH3.
a. What was the limiting reactant?
b. What was the theoretical yield, in grams, of cisplatin?
c. How many grams of the reactant in excess remained when the reaction was complete?
9.
Fill in the blank for the missing name or formula.
NAME
FORMULA
carbonate ion
sodium nitrate
tetraphosphorushexaoxide
ammonium chloride
copper (II) sulfate
H2SO4
AlCl3
OH1HCl
CO2
10.
The lab has a nitric acid (HNO3) solution with a density of 1.41 g/mL. The mass percent
of this solution is 65.0 % nitric acid. Clearly explain how you would prepare 500. mL of
a 3.25 M nitric acid solution using the solution available in the lab (described above).
11.
If 10.0 mL of 0.0975 M CaI2 solution are combined with an excess amount of an aqueous
solution of AgNO3. . .
a. How many moles of AgNO3 react?
b. How many grams of AgI will be formed?
12.
Bromine reacts violently with potassium as shown in the equation below,
2 Na(s) + Br2(l) → 2 NaBr(s)
a.
How many grams of Br2 would be needed to prepare 10.00 g NaBr?
b.
How many mL of Br2 would be needed to prepare 10.00 g NaBr? The density of
Br2 is 3.12 g/mL.
c.
How many molecules of Br2 are there in the mass of Br2 calculated in part a)?
13.
You have a sample of H3PO4 of unknown concentration. If it takes 35.46 mL of 0.100 M
Ca(OH)2 to neutralize 20.00 mL of the H3PO4 (to reach the titration endpoint) what is
the molarity of the unknown H3PO4?
14.
What would the density of ammonia gas (NH3) be if it were at a pressure of 696 mm Hg
and a temperature of 387 K?
15. i) Fill in the table for the following covalent compounds:
Molecule
BeCl2
NH3
SbCl5
Lewis Structure
Hybridization for
Central Atom
Geometry of The
Hybrid Orbitals
(Electron-Groups)
Angles Between
Atoms
ii) Fill in the blanks. For the molecule
there is a carbon to carbon sigma bond formed by the overlap of a
orbital of one carbon
with a
orbital of the other carbon. The only pi bond in the molecule is formed by the
overlap of a
orbital of carbon and a
orbital of oxygen.