Download Writing Formulas Worksheet 1. sodium nitrate 16. aluminum sulfide

UNIT 7 - CHEMICAL FORMULAS
Writing Formulas Worksheet
1. sodium nitrate
16. aluminum sulfide
2. iron (III) sulfate
17. strontium hydroxide
3. copper (I) phosphate
18. cesium carbonate
4. nickel (II) oxide
19. silicon dioxide
Duncan
5. potassium bromide
20. zinc chlorate
6. barium acetate
21. iron (II) phosphide
7. magnesium chromate
22. calcium nitride
8. silver sulfite
23. sodium bicarbonate
9. copper (II) chloride
24. ammonium dichromate
10. dinitrogen tetroxide
25. potassium iodide
11. rubidium sulfate
26. lead (II) acetate
12. beryllium nitrate
27. ammonium sulfide
13. phosphorus trichloride
28. silver carbonate
14. magnesium fluoride
29. ammonium phosphate
15. lead (II) bromide
30. nickel (II) iodide
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Naming Compounds Worksheet
1. NaCl
14. Ba3(PO4)2
2. Al2O3
15. Ni(ClO)2
3. CuSO4
16. ZnCr2O7
4. MgCl2
17. LiOH
5. (NH4)3PO4
18. AgHCO3
6. Pb(NO3)2
19. Fe(C2H3O2)3
7. K2CO3
20. CO2
8. NO2
21. Cu2CrO4
9. SrSO3
22. Al(OH)3
10. RbNO2
23. N2O
11. FeBr2
24. AgClO2
12. P2O5
25. CaI2
13. Cu(ClO3)2
26. SO2
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UNIT 7 - CHEMICAL FORMULAS
OXIDATION NUMBERS WORKSHEET
1.)
HCl
Cl:
11.)
H2SO3
2.)
KNO3
12.)
H2SO4
3.)
Fe(OH)3
*13.)
BaO2
4.)
Mg3N2
N:
14.)
KMnO4
5.)
KClO3
Cl:
*15.)
LiH
6.)
Al(NO3)3
16.)
MnO2
7.)
S8
17.)
OF2
8.)
Li2CO3
18.)
SO3
9.)
PbO2
19.)
NH3
10.)
NaHSO4
20.)
Na
N:
Fe:
N:
S:
C:
Pb:
S:
S:
S:
O:
Mn:
H:
Mn:
O:
S:
N:
Na:
Percent Composition Worksheet
Determine the percent composition of each of the following compounds.
1. KMnO4
K=
Mn =
O=
Duncan
2. HCl
3. Mg(NO3)2
H=
Mg =
Cl =
N=
O=
4. (NH4)3PO4
N=
H=
P=
5. Al2(SO4)3
Al =
S=
O=
O=
Solve the following problems.
6. How many grams of oxygen can be produced from the decomposition of 100. g of KClO3?
7. How much iron can be recovered from 25.0 g of Fe2O3?
8. How much silver can be recovered from 125 g of Ag2S?
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UNIT 7 - CHEMICAL FORMULAS
Empirical Formulas Worksheet
Find the empirical formula for each of the following substances. The percent composition is given.
1. 88.8 % copper & 11.2 % oxygen
2. 10.04 % carbon, 0.84 % hydrogen, & 89.12 % chlorine
3. 42.50 % chromium & 57.50 % chlorine
Duncan
4. 38.67 % potassium, 13.85 % nitrogen, & 47.48 % oxygen
*5. 72.40 % iron & 27.60 % oxygen
Part 2 – Determine the empirical formula of the following compounds using the given data.
6. Find the empirical formula for sodium sulfite. Sodium sulfite contains 36.5 % sodium,
25.4 % sulfur, and 38.1 % oxygen.
7. What is the empirical formula for a compound which contains 53.73 % iron and 46.27 %
sulfur?
8. What is the empirical formula of a compound if the percentage composition is:
aluminum 15.77 %, sulfur 28.11 %, and oxygen 56.12 %?
9. If 8.87 grams of phosphorus react with 11.43 grams of oxygen, what is the empirical
formula of the compound formed?
10. Phosgene, a poisonous gas used during World War I, contains 12.1 % C, 16.2 % O, and
71.7% Cl. What is the empirical formula for phosgene?
Molecular Formulas Worksheet
Solve the following problems.
1. A compound is found to be 40.0 % carbon, 6.7 % hydrogen, and 53.5 % oxygen. Its molecular mass is 60.
grams per mole. What is its molecular formula?
2. A compound is 64.9 % carbon, 13.5 % hydrogen, and 21.6 % oxygen. Its molecular mass is 74 grams per
mole. What is its molecular formula?
3. A compound is 54.5 % carbon, 9.1 % hydrogen, and 36.4 % oxygen. Its molecular mass is 88 grams per
mole. What is its molecular formula?
4. If the molecular mass of an oxide of nitrogen is 108. What is the molecular formula of a compound that
contains 4.02 grams of nitrogen and 11.48 grams of oxygen?
5. There are two different oxides of phosphorus. Both oxides can exist in different forms depending on the
temperature and pressure. Calculate the empirical and molecular formulas from the following data:
(A) P: 56.4 %, O: 43.7 %, molecular mass = 220
(B) P: 43.6 %, O: 56.4 %, molecular mass = 284
6. Nicotine is a compound that contains 74.0 % carbon, 8.7 % hydrogen, and 17.3 % nitrogen. If the molecular
mass is 162, what is the molecular formula?
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UNIT 7 - CHEMICAL FORMULAS
Composition of Hydrates Worksheet
Duncan
1. A hydrated sodium salt containing 39.7 % water is analyzed as follows: Na 16.9 %, C
17.7 %, H 6.67 %, and O 58.8 %. What is the empirical formula of this salt?
2. Nicotine is a compound that contains 74.0 % carbon, 8.7 % hydrogen, and 17.3 %
nitrogen. If the molecular mass is 162, what is the molecular formula?
3. Strontium hydroxide is isolated as a hydrate, which means that a certain number of water
molecules are included in the solid. When 6.85 grams of the hydrate are dried in an oven,
3.13 grams of anhydrous Sr(OH)2 are formed.
4. A 2.5 gram sample of a hydrate of Ca(NO3)2 was heated, and only 1.7 grams of the
anhydrous salt remained. What percentage of water was in the hydrate?
5. A 5.0 gram sample of Cu(NO3) 2 . n H2O is heated, and 3.9 gram sample of the
anhydrous salt remains. What is the value of n?
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UNIT 7 - CHEMICAL FORMULAS
EMPIRICAL FORMULA OF A HYDRATE LAB
Many salts crystallized from water solutions appear to be perfectly dry, yet when heated, they liberate large
quantities of water. The crystals change form, even color, as the water is driven off. Such compounds are called
hydrates. The number of moles of water present per mole of anhydrous salt (salt minus water of crystallization)
is usually a whole number. One example is the hydrate of copper (II) sulfate. Its blue crystals look and feel dry.
Yet each mole of hydrate contains 5 moles of water. Its formula is CuSO4 . 5 H2O. The dot between the CuSO4
and the 5 H2O does NOT mean multiplication. It indicates that 5 water molecules are bound to the other atoms.
The molar mass of CuSO4 . 5 H2O is 249.6 g/mole.
Duncan
In this experiment, you will determine the empirical formula of a hydrate. You will do so by heating the hydrate
to drive off the water. You will measure the mass of the water driven off the hydrate by heating it and you will
measure the mass of the anhydrous salt that remains. By calculating the number of moles of water driven off
and the number of moles of anhydrous salt remaining, you will be able to find the empirical formula of the
hydrate.
Materials
3 - 5.25" glass test tubes
ring stand, wire gauze, iron ring, & burner
hydrated salt
wood splint spatula for transferring solid to test tubes
Procedure
*PUT YOUR GOGGLES & APRON ON NOW!*
1. Obtain and label three dry test tubes #1, #2, and #3. Weigh the test tubes to the nearest 0.01 g. Record
these data on the data table below. Remember to zero the balance each time you use it. Also remember to
use the same balance throughout the experiment.
2. Add 0.5 - 0.8 g of the hydrate to each of the test tubes. Do not pack the crystals.
3. Reweigh the three test tubes and record the masses, again to the nearest 0.01 g.
4. Lay the test tubes on the square wire gauze. Turn the corners of the wire gauze up slightly so the test tubes
do not roll off. You must be able to heat the entire length of the test tube with the burner to drive off all the
water of hydration. Place the wire gauze and the three test tubes on the iron ring and heat the three samples
gently and evenly along their entire lengths.
5. Heat the test tubes by gently waving the burner flame back and forth underneath the wire gauze. Record any
observations you make during the heating process.
6. Heat for approximately 5 minutes. Allow the test tubes to cool before handling. This may take several
minutes. (Remember that the glass is very hot even though it may appear to be cool.)
7. Weigh the three samples and record the data.
8. Reheat the three samples for an additional five minutes, cool, and reweigh until the mass of the anhydrous
salt and test tube is constant. What does “anhydrous” mean?
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UNIT 7 - CHEMICAL FORMULAS
DATA TABLE
Trial 1
Trial 2
Trial 3
1
2
3
4
5
mass of empty test tube (g)
mass of hydrate & test tube (g)
mass after 1st heating (g)
mass after 2nd heating (g)
constant mass of anhydrous salt &
test tube (final mass, g)
6 mass of water driven off (g)
7 # of moles of water
8 molar mass of anhydrous salt
(______________)
9 grams of anhydrous salt (g)
10 moles of anhydrous salt
11 mole ratio of H2O to anhydrous
salt
12 Empirical formula of hydrate experimental
13 Empirical formula of hydrate theoretical
Calculations
Show all calculations necessary to calculate the empirical formula for the hydrated salt. You have to show your
work for only one trial.
Grading
To receive full credit, the data table must be filled in completely and correctly for all three trials. You must
include a sample calculation sheet along with your data table
**CRITERIA IN ORDER TO RECEIVE CREDIT FOR THIS ASSIGNMENT:
* All numbers are clear & legible.
* All numbers are labeled with their correct units.
* Calculations are shown in detail.
* Calculations are shown in a neat and logical order.
* No messy cross-outs or eraser marks.
* Failure to follow these criteria will result in your having to re-submit your lab. It will be considered a late grade
when you re-submit.
THIS LAB IS DUE ON:
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