Conceptual Chem
Name KEY KEY KEY
1B Review KEY!
Unit 1 Section B - Looking at Water and Its Contaminants – A Review
Physical Properties
1.
Name two physical properties would allow you to distinguish between liquid
water and rubbing alcohol. Odor, boiling point, freezing point, density
Density
2.
A graduated cylinder has a mass of 125 g. When a sample of an unknown liquid
is placed in the cylinder, its new mass is 155 g. The volume of the liquid is
25 mL. What is the density of the liquid?
155 – 125 = 30. g of liquid
3.
D = m/v
D = 30.g/25 mL = 1.2 g/mL
If the liquid in question 2 is insoluble in water, will it sink or float in the water?
How do you know? Sink. It has a higher density.
4. A block has measurements of 6.00 cm, 17.0 cm, and 5.20 cm. The density of the
block is 1.85 g/cm3. What is the mass of the block?
V = L x W x H = 6.00 cm x 17.0 cm x 5.20 cm = 530. cm3
D = m/v so… 1.85 g/cm3 = m/ 530 cm3
so… m = 981 g
Classification of Matter
5.
What does the symbol (aq) following the formula for a compound mean? Would
this substance be an element, a compound, a solution or a heterogeneous mixture?
Aqueous (definition): mixed with water. This substance would be a solution.
6.
Classify the following substances as homogeneous or heterogeneous.
Homo a.
Cl2
Hetero e.
oil and water
Homo b.
potassium
Homo f.
air
Homo c.
KCl(aq)
Hetero g.
sedimentary rock
Homo d.
KNO3
Homo h.
a solution
7.
Classify the following substances as pure substances or mixtures.
pure a.
Cl2
mix
e.
oil and water
pure b.
potassium
mix
f.
air
mix
KCl(aq)
mix
g.
sedimentary rock
KNO3
mix
h.
a solution
c.
pure d.
8.
9.
Classify the following substances as an element, compound, homogeneous
mixture or heterogeneous mixture.
element
a.
Cl2
hetero mix
e.
oil and water
element
b.
potassium
homo mix
f.
air
homo mix
c.
KCl(aq)
hetero mix
g.
sedimentary rock
compound
d.
KNO3
homo mix
h.
a solution
Carbon tetrachloride, CCl4 is a liquid that can be used in dry cleaning. When
5.0 g of bromine is added to 75 g of clear colorless CCl4, the mixture has a
reddish brown color. Over time, no settling out is observed. When the mixture is
filtered, no residue is observed on the filter paper. When a light beam is directed
at the mixture, its path through the mixture is not visible. Is the mixture a
solution, colloid or suspension? Explain your answer. It is not an element and
it is not a compound: it is a mixture. Since light doesn’t pass through the
mixture, it shows the Tyndall effect (so it is not a solution). Since it doesn’t
settle, it is not a suspension. The mixture is a colloid.
Symbols, Formulas and Equations
10.
Give the symbol for each element present in each molecule of Al2(SO4)3 and tell
how many of atoms of each element are present.
Al – 2 atoms
S – 3 atoms
O – 12 atoms
Electrical Charges, Protons, Electrons, Atoms and Ions
11.
Classify the following as anions, cations, or electrically neutral atoms.
a.
Rb+1 cation
c.
Se–2 anion
b.
CrO4–2 anion
d.
Sn neutral
12.
13.
14.
Give the symbol and electrical charge for each of the following ions or atoms.
Au+3
a.
gold
He
b.
F-1
c.
79
protons
76 electrons
Helium
2
protons
2 electrons
fluorine
9
protons
10 electrons
For each of the atoms or ions, identify the number of protons and electrons.
a.
P–3
15
protons
18
electrons
b.
Zn
30
protons
30
electrons
c.
Ba+2
56
protons
54
electrons
Give the symbol and charge for each of the following ions:
Ca+2 a.
calcium atom that lost 2 electrons
N-3
b.
nitrogen atom that gained 3 electrons
15.
Were electrons gained or lost in order to form Be+1? Also explain what is wrong
with the first part of this question. One electron was lost. This isn’t correct
because Beryllium should lose 2 electrons according to the periodic table.
16.
Complete the following table.
Cation Anion Formula
Mg 2+ O2–
MgO
Name
Magnesium oxide
Al3+
Cl–
AlCl3
Aluminum chloride
Mg2+
PO4–3
Mg3(PO4)2
Magnesium phosphate
NH4+
CO32–
(NH4)2CO3
Ammonium carbonate
Fe+3
SO3-2
Fe2(SO3)3
Iron(III) sulfite
Ca+2
Cl-1
CaCl2
Calcium chloride
Cu+2
NO3-1
Cu(NO3)2
Copper (II) nitrate
Al+3
OH-1
Al(OH)3
Aluminum hydroxide