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Unit 2: Nomenclature and Formula Writing
VT Field of Knowledge Standard
7.12 Students understand forces and motion, the properties and composition of matter, and energy
sources and transformations.
Field of Knowledge
Evidence
aaa. Observe and measure
characteristic properties of, and
chemical reactions between, one
substance and another to
distinguish between them; explain
the structure of matter using the
periodic properties of elements.
bbb. Demonstrate an understanding of
the atomic structure of matter in
relationship to the periodic table,
bonding, elements and
compounds;
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Basic Concepts
1.
2.
3.
4.
5.
Chemistry is the study of matter. Matter is
divided into pure (elements and
compounds) and impure (mixtures)
substances.
Physical and chemical properties allow us
to identify matter as elements, compounds,
ions, or mixtures.
Elements, compounds, and ions can be
represented using a standard system of
nomenclature.
Atoms are the smallest pieces of an
element; ions are atoms that carry an
electrical charge.
6.02 X 1023 particles (“Avogadro’s
Number”) is called a “mole”.
Assignment
Read sec 4.1-4.2 (Elements/symbols)
Pg 113, #1-8, 12,14
Read 4.4, skim 4.5-4.6,Read 4.7(atom basics)
Pg. 114, #19, 20 ,39, 41
Read 4.8 (periodic table)
Pg. 116, #43-51 odd
Read 5.1 – 5.5 (Ions/compounds/nomenclature) Lots here, but important!!
Pg 158. #1-9 odd, 20, 27,29
Read 5.5 – 5.10 (again – a lot, but… !!!) (binary ionic problems)
Pg 160 #37-44 a-d for each
Pg160 #46-50 a-d for each (binary practice, both types)
Pg 161 #59-64 a-d for each (polyatomic compounds)
Pg161 #65-68 (acids)
Pg 162# 69-76 (Lots and lots of practice!!)
Page 164 – 165 (ionic compounds chart)
Fill in tables 5.A and 5.B (not in the book!)
Read 9.2 – 9.4(molar mass, mole conversions)
Pg. 276 #19 – 24, but only a – e of each
Read 9.5 – 9.8 (% composition, emp formulas)
Pg. 280 #71 – 74
Read 7.2, 7.3(ppts)
Pg. 214 #11,12,17, 18 a-d for each (ppts)
Packet pg 2-3(review)
Packet page 6(Molar mass, conversions)
Packet pg 7-8(percent mass)
Practice test (packet 9-11)
Due
Nomenclature Practice
1.
2.
In which group do the following substances belong? Your choices are 1) metallic element, 2) non-metallic
element, 3) compound, 4) heterogeneous mixture, and 5) homogeneous mixture.
a. beach sand
b. silicon dioxide
c.
aluminum foil
d. ginger ale
e.
air
f. copper(II) sulfate
g.
quartz
h. granite
i.
NaCl solution
j. milk
Give the formula or name of the following:
a. calcium nitrate
b. lead(IV) carbonate
c.
ammonium hydroxide
d. zinc oxide
e.
copper(I) sulfite
f. copper(II) sulfite
g. NaBr
h. KI
i. MgO
j. BaCl2
k. N2O
l. N2O4
m. PCl3
n. P4O10
5.
A cheetah is able to run at a speed of 60 miles/hour. Use dimensional analysis only to answer this question:
how many meters can a cheetah run in 30 seconds?
6.
Write the names of the following compounds.
a. Na3PO4
b. (NH4) 2CO3
c.
d. Al2O3
MgS
2
7.
Write the correct formula for the following compounds.
a. copper(II) carbonate
b. silver nitrate
c.
magnesium phosphate
d. ammonium chloride
8.
Two clear solutions are mixed in a test tube, and a white precipitate forms. The first solution is barium iodide.
The second solution is potassium phosphate. KI is soluble in water. Write the formula of the precipitate. [You
will need to use your solubility rules.]
9.
Suppose that every milliliter of seawater contains 35 mg of NaCl. How many grams of sodium chloride are in
10.0 gallons of seawater? Express your answer in scientific notation.
10. Name 'em.
a. Al2S3
b. CS2
c. CoCl2 · 6H2O
d.
SnCO3
e. BF3
f. SiF4
g.
KMnO4
h. N2O4
i. (NH4) 2S
11. Write the formulas for the following acids:
a. hydrobromic acid
b. chloric acid
d.
phosphoric acid
e. hydrosulfuric acid
g.
perchloric acid
h. acetic acid
c. nitric acid
f. hydrocyanic acid
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j. NH3
Mole Conversions, Percent Composition, and Finding Formulas
Key things to remember:
1.
2.
3.
4.
1 mole=Avogadro’s # = 6.022 x 1023 = really big number
1 mole of any substance weighs its molar mass in grams
When in doubt, ALWAYS change to moles.
When confused, use dimensional analysis to get to a desired unit.
To find molar mass
1. Find or use a correct molecular formula.
2. Use atomic weight of each substance to determine molar mass.
Example:
Fe2O3
Fe = 55.85 g O = 16.00 g
There are 2 iron atoms and 3 oxygen atoms. Therefore:
55.85(2) + (16.00)3 = 159.7 g/mol
To convert to moles, given grams
1. Find the molar mass of the substance
2. Use dimensional analysis to find moles
Example
How many moles is 247.3 g of iron (III) oxide?
The molar mass of Fe2O3 = 159.7 g/mol (from previous example)
247.3 g * 1 mol = 1.549 moles
159.7 g
* notice that the units cancel to get moles
To convert to grams, given moles
1. Find the molar mass of the substance
2. Use dimensional analysis to find the grams
Example
How many grams is 5.032 moles of Fe2O3?
Fe2O3 = 159.7 g/mol
5.032 mol * 159.7 g = 803.61 g Fe2O3
1 mol
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To figure out number of molecules or atoms
1. Convert to moles of the substance
2. Multiply moles times Avogadro’s number
Example:
How many molecules of iron (III) oxide are in the last problem?
5.0322 moles * 6.022 * 1023 = 3.029 x 1024 molecules Fe2O3
To convert to atoms
1. Same as above, but use ratio of atoms to molecules first
2. Then multiply moles times Avogadro’s number
3. When in doubt, dimensional analysis!
How many moles of O atoms in 5.032 moles of Fe2O3?
5.032 moles Fe2O3 *
3O
* 6.022 *1023
1 Fe2O3
1 mole
= 9.091 * 1024 atoms O
To find percent composition of a compound
1. Find molar mass of the compound
2. Find mass of each constituent of the compound using atomic mass and number of atoms of
each.
3. Divide constituent mass by molar mass and multiply by 100 (% = part/whole * 100)
4. The check is to be sure percents add to 100%
What is the % composition of Fe2O3?
Fe2O3 = 159.7 g/mol
2 Fe atoms 3 O atoms
2 Fe = 55.847 * 2 = 111.694 g / 159.7 g * 100 = 69.94 %
3 O = 16.00 * 3 = 48.00 g / 159.7 g * 100 = 30.06 %
Check: 69.94 + 30.06 = 100
To find the formula of a compound, given percent
1.
2.
3.
4.
5.
Assume that there is 100 g of the compound. Therefore 100% of it = 100 g
Change percents to g
Change grams to moles
Find the ratios of the moles, in whole numbers. (Do this by dividing all moles by the smallest # of moles)
Put whole numbers into the molecular formula.
69.94 % Fe = 69.94 g Fe * 1 mole = 1.252 moles
55.847 g
30.06 % O = 30.06 g O *1 mole = 1.879 moles
16.00 g
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1.252 to 1.879 = 1 to 1.5
to get to whole numbers, double
them both, so that there are 2 Fe to
3O
Moles, Molecules, and Grams Worksheet
1)
How many molecules are there in 24 grams of FeF3?
2)
How many grams are there in 7.4 x 1023 molecules of AgNO3?
3)
How many molecules are there in 122 grams of Cu(NO 3)2?
4)
How many grams are there in 9.4 x 1025 molecules of H2?
5)
How many molecules are there in 2.3 grams of NH4SO2?
6)
How many molecules are there in 200 grams of CCl 4?
7)
How many grams are there in 4.5 x 1022 molecules of Ba(NO2)2?
Name
8)
A karat is a measure of purity of gold for jewelry. 24 k is pure gold, with anything less related to the ratio of
other metals mixed in. For example a 5 karat necklace is 5 parts gold out of 24 total parts. How many moles and
molecules of gold are there in a 4.05 gram earring made from 18 karat gold?
9) Find the mass percent of each constituent for the compound barium nitrate.
10) Determine the formula for a compound that, when decomposed, is 1.00 g of Ba and 0.1117 g of O. (Sample
problem, page 268 in text)
Most scrambled answers (note: sig figs are inconsistent and at times wrong…): 7.82 x 1023 molecules 421 grams 209 grams 1.69 x
1022 molecules
312 grams
3.92 x 1023 molecules
1.28 x 1023 molecules
1.33 x 1023 molecules
1.91 x 1024 molecules
122 grams
1.07 x 1024 molecules
430 grams 195 grams 3.96 x 10 24 molecules
17.1 grams
2.51 grams
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Name
Percentage Mass
1.
2.
Determine the formula and name of the following substances, given their percent compositions and molar
masses.
a. 64% Fe; 36% S; molar mass = 88
b. 41% Cu; 18% N; 41% O; molar mass = 155.5
c. 40% S; 60% O; molar mass = 80
d. 2% H; 33% S; 65% O; molar mass = 98
e.100% O; molar mass = 48
f. 65% Ag; 16% Cr; 19% O; molar mass = 332
A student is attempting to experimentally determine the formula for a compound consisting of the elements
mercury and oxygen. The compound is an orange powder which, when heated, undergoes a "decomposition"
reaction -- it falls apart. Initially, the mercury and the oxygen are joined together by chemical bonds, and heat
causes the bonds to break, and oxygen is thus separated from the mercury. Here is the data collected for the
experiment; you finish it.
mass of test tube
mass of test tube + orange powder
mass of test tube after heating*
14.564 g
14.981 g
14.951 g
*After
heating, the inside of the test tube was coated with a mirror-like, silvery finish, which collected in small
liquid beads eventually.
mass of the orange powder
_______
mass of the mercury in the compound
_______
mass of the oxygen in the compound
_______
% mercury in the compound
_______
% oxygen in the compound
_______
Empirical Formula for the compound
_________
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3.
Use dimensional analysis.
a. If you had 14.54 grams of NaCl, how many moles would you have? (1 step)
b. How many molecules of sulfur dioxide are in 100 grams of the gas? (2 steps)
c. What is the mass of exactly one atom of hydrogen? (2 steps)
d. The formula for anhydrous iron(III) sulfate will tell you how many atoms of oxygen are in every molecule of
the compound. If you had 0.237 moles of iron (III) sulfate, how many atoms of oxygen would you have?
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Practice Nomenclature and Formulas and Moles and Composition Test
Choose the best answer for the following multiple choice questions. 2 pts each.
____ 1. The correct name for K2S is:
a. potassium sulfate
b. dipotassium monosulfide c. potassium sulfide
d. potassium monosulfide
____ 2. In general, it can be said that:
a. non-metals become positive ions
b. non-metals lose electrons to become ions
c. non-metal ions are always negative
d. all of the above
e. none of the above
____ 3. Something that is covalently bonded:
a. Is a metal bonded to metal
b. contains only ions
c. donates electrons
d. is a nonmetal bonded to a nonmetal
____ 4. Iodine forms an ion with a charge of:
a. +1
b. +7
c. –2
d. –1
____ 5. Which of the following is not ionic?
a. NaCl
b. magnesium permanganate
____ 6. In naming, the Roman numeral is used to:
a. Indicate the charge on the metal
c. indicate the charge on the non-metal
c. sulfur tetrafluoride
d. Al2O3
b. indicate how many metal ions are present
d. tell how many electrons are gained
____ 7. What is the percent composition of C in methane, CH 4?
a. 25%
b. 133%
c. 75%
d. 92%
____ 8. There are ____ atoms of nitrogen in 10 g of NH 4NO3?
a. 3.5 b. 1.5 x 1023
c. 7.5 x 1022
d. 1.8
e. 7.7%
e. 2
____ 9. How many moles of carbon dioxide are there in 52.06 g of carbon dioxide?
a. 0.8452
b. 1.183
c. 6.022 x 1023
d. 8.648 x 1023
____ 10. An unknown element X forms compounds with ferricyanide ions which have the following formulas:
X3[Fe(CN) 6] 2 and XFe(CN) 6. Which of the following is a possibility for element X?
a. copper
b. lead
c. sodium
d. iron
11. Write the names of all the following compounds, the type of compound it is, and determine the molar mass.
Don’t forget units! (1 pt each, 18 total)
Formula
a. H3PO4
Name
b.
Sulfur dioxide
Molar mass
c. Al2S3
d.
Iron (II) sulfate
e. ZnCr2O7
f.
Hydrobromic acid
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Ionic/covalent/acid?
12. Write the formula or give the name for the following: (2 pts each)
a. sulfurous acid
b. CBr4
c. lead (IV) sulfate
d. copper (I) sulfite penta hydrate
e. dinitrogen tetroxide
f. Li(OH)2
g. sulfurous acid
h. H3P
For the rest of the problems, show all work.
13. Consider allicin, C6H10OS2, the chemical responsible for the small of garlic:
a. What is the molar mass of allicin (2 pts):
b. What is the mass percent of the carbon in allicin? (4 pts)
c. If a clove of garlic contains 0.0013 grams of allicin, how many moles is this? (4 pts)
d. How many atoms of sulfur are there in part c? (4 pts)
14. If a penny weighs 2.50 grams, and is 2.5% copper, how many moles of copper are in one penny?
(Find grams Cu first.) 6 pts
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15. 1.384 moles of Ba(OH)2 weighs how much, in grams? 4 pts
16. A compound analyzed by mass spectrometer is determined to have 40.0% carbon, 6.7% H, and 53.3% oxygen.
The molecular mass of the compound is 180 g/mol. What are the empirical and molecular formulas for the
compound? 6 pts
17. An unlabeled bottle is left out on the lab table. The last lab only used barium nitrate, silver nitrate, and iron (II)
nitrate, so the unknown solution must be one of these. Devise an experiment that could identify the cation that is
contained in the solution. Write out the steps, including any reaction equations that could occur. The bottle contains
only one cation. (10 pts)
Solubility of common ions in water
1. Nitrate salts are soluble.
2. Salts of Na, K, and NH4 ions are soluble.
3. Most halide (Cl, Br, I) salts are soluble. Exceptions: Ag+, Pb2+4.
4. Most sulfate salts are soluble. Except: BaSO4, PbSO4, CaSO4
5. Most hydroxide compounds are insoluble. Soluble hydroxides
include NaOH, KOH, and Ca(OH)2
6. Most sulfide, carbonate, and phosphate salts are insoluble.
Exceptions: Rule 1 and 2 ions
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Solubility Rules for Common Ions in Solution
In many reactions between ions, a precipitate can form. A precipitate is when a solid
forms in solution. A precipitate is an insoluble form of a salt. Precipitates do not always
form when ions interact. The rules listed below can help to determine if a precipitate
forms, and what the formula for the precipitate is.
Usually Soluble
1. All chlorates, nitrates and acetates are soluble.
2. Salts of group I compounds (H+, Na+, Li+, K+, Rb+, Cs+) and ammonium (NH4+) are soluble.
3. Halides (Cl-, Br-, I-) are soluble, except for those of silver, lead (II) and mercury (I) ions.
4. Sulfates are soluble except for those of mercury (I), lead (II), barium, and strontium ions.
5. Nitrites are soluble except for silver nitrite.
Usually insoluble
6. Carbonates, phosphates and oxides are all insoluble except ions in rule 2.
7. Fluorides are insoluble, except for silver, iron (III) and the ions in rule 2.
8. Sulfides and hydroxides (OH-) are insoluble, except for strontium, barium and the ions in rule 2.
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