Make your own free website on Tripod.com

<>

MOLE AND PERCENT WORKSHEET

<>

1. How many pennies are in a mole of pennies? How many thousand-dollar bills (k-notes!) is that mole of pennies equal to?

<>

2. NO2 is the molecular formula for nitrous dioxide (also known as nitrogen dioxide). List the information available to you from this formula?.

<>

3. C2H2 is the molecular formula for ethylyne (A.K.A. acetylene). (a) How many atoms are in one molecule? (b) Which atoms make up acetylene? (c) How many moles of atoms are in one molecule of acetylene? (d) How many molecules are in 5.3 moles of acetylene? (e) How many atoms are in a mole of acetylene?

<>

4. Calculate the molar mass of a mole of the following materials: (a) Al (b) Ra (c) Co (d) CO (e) CO2 (f) HCl (g) Na2CO3 (h) Ca(NO3)2 (i) (NH4)3(PO4) (j) H2O (k) Epsom salts - Mg(SO4)7H2O (m) blue vitriol - Cu(SO4)5H2O ?

<>

5. Calculate the number of moles in: (a) 2.3 # of carbon (b) 0.014 g of Tin (c) a 5 Oz silver bracelet (d) a pound of table salt (e) a 350 kg cast iron engine block (f) a gal. of water (8.3 #) (g) a ton of sand (SiO2) (h) 6.2 grams of blue vitriol (i) a pound of Epsom salts ?

<>

6. Calculate the number of atoms in: (a) 100 g of Argon (b) 1.21 kg aluminum foil (c) a 28 # lead brick (d) the E7 kg of water in an olympic swimming pool (e) 7 kg of hydrogen gas (f) a tonne of calcium nitrate ?

<>

7. What is the percentage composition of oxygen in each of the following materials: (a) CO (b) CO2 (c) (NO3)- (d) isopropyl alcohol C3H8O (e) calcium nitrate (f) blue vitriol - Cu(SO4)5H2O ?

<>

8. What is the percentage composition of phosphate in each of the following materials: (a) phosphoric acid (b) sodium carbonate (c) ammonium phosphate (d) calcium phosphate ?

<>

9. What is the percentage composition of sulfate in each of the following materials: (a) sulfuric acid (b) sodium sulfate (c) Epsom salts ( d) aluminum sulfate ?

ANSWERS TO MOL AND PERCENT PROBLEMS

1a. 6.023 E23 pennies

1b. 6.023 E18 k-Notes

2a. Covalent

 

 

 

 

 

2b. Elements in it (N and O)

2c. Number of atoms of each element

 

 

 

 

 

3a. 4

3b. C & H

3c. 6.64 E-24

3d. 3.1922 E24

3e. 2.4092 E24

 

 

 

 

 

4a. 27.0

4b. 226.0

4c. 58.9

4d. 28.0

4e. 44.0

 

 

 

 

 

4f. 36.5

4g. 106.0

4h. 164.1

4i. 149.0

4j. 18.0

 

 

 

 

 

4k. 246.4

4m. 249.6

5a. 86.9

5b. 1.18 E-4

5c. 1.31

 

 

 

 

 

5d. 7.75

5e. 6.27 E3

5f. 210

5g. 1.51 E4

5h. 0.0248

 

 

 

 

 

5i. 1.84

6a. 1.51 E24

6b. 2.69 E25

6c. 3.69 E25

6d. 1.00 E33

 

 

 

 

 

6e. 4.22E27

6f. 3.30 E28

7a. 57.1%

7b. 72.7%

7c. 77.4%

 

 

 

 

 

7d. 26.7%

7e. 58.5%

7f. 57.7%

8a. 96.9%

8b. 0%

 

 

 

 

 

8c. 63.8%

8d. 61.2%

9a. 98.0%

9b. 67.6%

9c. 39.0%

 

 

 

 

 

9d. 84.2%

 

 

 

 

 

 

 

 

 

Back to the beginning of Mols, Percents, and Stoichiometry.


<>

STP GAS AND MASS STOICHIOMETRY PROBLEMS (PRELIMINARY TO GAS LAW)

All of the problems below are stoichiometry problems with at least one equation participant as a gas at STP. (a) Write and balance the chemical equation. (2) Do the math in DA style using 1 mole gas at STP = 22.4 liters as a factor. In the following problems ALL GASES ARE AT STP. Click here for a general idea of how to do the problems in this set.

<>

1. How many moles of nitrogen gas is needed to react with 44.8 liters of hydrogen gas to produce ammonia gas?

<>

2. How many liters of ammonia are produced when 89.6 liters of hydrogen are used in the above reaction?

<>

3. Ten grams of calcium carbonate was produced when carbon dioxide was added to lime water (calcium hydroxide in solution). What volume of carbon dioxide at STP was needed?

<>

4. When 11.2 liters of hydrogen gas is made by adding zinc to sulfuric acid, what mass of zinc is needed?

<>

5. What volume of ammonia at STP is needed to add to water to produce 11 moles of ammonia water?

<>

6. How many grams of carbonic acid is produced when 55 liters of carbon dioxide is pressed into water?

<>

7. magnesium hydroxide + ammonium sulfate <> magnesium sulfate + water + ammonia

How much (grams) magnesium hydroxide do you need to use in the above reaction to produce 500 liters of ammonia?

<>

8. How much strontium bromide is needed to add to chlorine gas to produce 75 liters of bromine?

<>

9. What mass of ammonium chlorate is needed to decompose to give off 200 liters of oxygen?

<>

10. Your car burns mostly octane, C8H18, as a fuel. How many liters of oxygen is needed to burn a kilogram of octane?

<>

11. copper + sulfuric acid <> copper II sulfate + water + sulfur dioxide

How many moles of copper are needed to produce 1000 L of SO2?

<>

12. What volume of oxygen is needed to burn a pound of magnesium?

<>

13. How many grams of sodium do you have to put into water to make 30 liters of hydrogen at STP?

<>

14. ammonia gas and hydrogen chloride gas combine to make ammonium chloride. What volume of ammonia at STP is needed to react with 47.7 liters of hydrogen chloride at STP?

<>

15. How many liters of oxygen are needed to burn 10 liters of acetylene?

ANSWERS TO STP GAS AND MASS STOICHIOMETRY PROBLEMS

1. 0.667 mol

2. 59.7 L

3. 2.24 L

4. 32.7 g

 

 

 

 

5. 246 L

6. 152 g

7. 651 g

8. 828 g

 

 

 

 

9. 604 g

10. 2.46 kL

11. 44.6 mol

12. 210 L

 

 

 

 

13. 61.6 g

14. 47.7 L

15. 25 L

 

Back to the beginning of Mols, Percents, and Stoichiometry.


<>

PROBLEMS ON CONCENTRATION AND DENSITY

WRITE AND BALANCE THE CHEMICAL EQUATION FOR THOSE PROBLEMS THAT NEED IT. SHOW ALL YOUR WORK. USE W5P OR DA METHOD ACCORDING TO THE ROADMAP.

1. The lead brick on my desk measures 3 by 5 by 11 cm. Lead has a density of 11.34 g/cc. How many lead atoms are in that block?

2. The lab technician at the Planter's Peanut packing factory takes a bag of peanuts, puts water into it to dissolve the salt, and dilutes the solution to one liter. She then takes ten ml of that solution and titrates it against 0.132 M silver nitrate. One bag sample takes 31.5 ml of silver nitrate to endpoint. What mass of salt was in the bag?

3. What is the concentration of sugar (C12H22O11) if twenty grams are dissolved in enough water to make 2 liters?

4. Methyl alcohol (CH3OH) has a density of 0.793 kg/l. What volume of it is needed to add to water to make five liters of 0.25 M solution?

5. Magnesium has a density of 1.741 g/cc. What volume of Mg will burn in 20 liters of oxygen at 2.1 atm and 0C?

6. Uranium metal can be purified from uranium hexafluoride by adding calcium metal. Calcium metal has a density of 1.54 g/cc. Uranium has a density of 18.7 g/cc. What mass of uranium do you get for a Kg of Ca? What volume of uranium do you get for a cubic meter of calcium?

7. What volume of 0.27 M sodium hydroxide is needed to react with 29.5 ml of 0.55 M phosphoric acid?

8. What volume of carbon dioxide is produced at 1 atm and 87 C when 1.6 liters of methyl alcohol burns? What volume of liquid water is produced in this reaction?

9. Seven kilograms of mercury II oxide decomposes into mercury and oxygen. Mercury has a density of 13.6 g/cc/ What volume of mercury is produced?

10. Water and calcium oxide produce calcium hydroxide. How many grams of calcium hydroxide are made if you add 275 liters of water to enough calcium oxide?

11. Gasoline (C7H16) has a density of 0.685 kg/liter. How many liters of oxygen at 37 C and 950 mmHg are needed to burn 15 liters of gasoline?

12. Sodium hydroxide and hydrochloric acid combine to make table salt and water. 14 mL of 0.1 M sodium hydroxide is added to an excess of acid. How many moles of table salt are made? How many grams of salt is that?

13. 50 mL of 0.25 M copper II sulfate evaporates to leave CuSO45H2O. (That is the pentahydrate crystal of copper II sulfate.) What is the mass of this beautiful blue crystal from the solution?

14. Chlorine gas is bubbled into 100 mL of 0.25 M potassium bromide solution. This produces potassium chloride and bromine gas. The bromine (which dissolves in water) is taken from the solution and measured at 27 C and 825 mmHg. What is the volume of bromine?

15. 95.0 mL of 0.55 M sulfuric acid is put on an excess of zinc. This produces zinc sulfate and hydrogen. How many grams of zinc sulfate are made?

16. 27.6 mL of a 0.190 M solution of silver nitrate and 15.4 mL of an unknown (but excess) amount of sodium chloride combine to make a white precipitate silver chloride and some dissolved sodium nitrate. (a) How many moles of silver chloride are made? (b) How many grams of silver chloride is that? (c) How many moles of sodium nitrate are made? (d) What is the concentration of sodium nitrate in the final solution?

17. How many grams of potassium permanganate, KMnO4, is needed to make 1.72 liters of 0.29 M solution?

18. By my calculations, a drop of ethyl alcohol, C2H5OH , in an olympic-sized swimming pool produces a 1.20 E-10 M solution of alcohol in water. A drop is a twentieth of a mL. How many molecules of ethyl alcohol are in a drop of the water in the pool?

19. 93.0 mL of 0.150 M magnesium hydroxide is added to 57.0 mL of 0.4 M nitric acid. (Magnesium nitrate and water are formed. What is the concentration of the magnesium nitrate after the reaction?

ANSWERS TO PROBLEMS ON CONCENTRATION AND DENSITY

1. 5.44 E24 atoms

2. 24.3 g

3. 0.0292 M

4. 0.0504 L

 

 

 

 

5. 52.3 ml(cc) Mg

6a. 1.98 kg of U

6b. 1.63 E6 mL

7. 180 mL

 

 

 

 

8a. 1.17 kL CO2

8b. 1.43 L

9. 0.477 L

10. 1.13 E 6 g

 

 

 

 

11. 23.0 kL

12a. 1.4 E-3 mols

12b. 0.0819 g

13. 3.12 g

 

 

 

 

14. 284 mL

15. 8.44 g

16a. 5.24E-3 mol

16b. 0.752 g

 

 

 

 

16c. 5.24E-3 mols

16d. 122 mmolar

17. 78.8 mg

18. 3.61E9 molecules

 

 

 

 

19. 0.152 M

 

 

 

Back to the beginning of Mols, Percents, and Stoichiometry.


<>

PROBLEMS USING COMPLETE ROADMAP

1. How many liters of ammonia at 0 C and 25 atm. are produced when 10 g of hydrogen is combined with nitrogen?

2. How many milliliters of hydrogen at 0 deg C and 1400 mmHg are made if magnesium reacts with 15 mL of 6 M sulfuric acid?

3. How many atoms are in 25 liters of fluorine gas at 2.85 atm and 450 C?

4. Liquid butane (C4H10 has a density of 0.60 g/cc. It burns to make carbon dioxide at 120 C. What volume of carbon dioxide is produced at one atm when 350 liters of liquid butane burns?

5. Isopropyl alcohol, C3H7OH , makes a good fuel for cars. What volume of oxygen at 785 mmHg and 23 C is needed to burn 8.54 E25 molecules of isopropyl alcohol?

6. How many moles of NaCl are in a liter of a 0.15 M NaCl solution? (0.15 M NaCl is physiological saline when sterilized.)

7. How many grams of NaCl must you put into a 50 liter container to make a physiological saline solutionxmol4.htm - 7?

8. Chlorine gas is bubbled into 100 mL of 0.25 M potassium bromide solution. This produces potassium chloride and bromine gas. The bromine dissolves completely in the water. What is the concentration of bromine?

9. 95 mL of 0.55 M sulfuric acid is put on an excess of zinc. This produces zinc sulfate and hydrogen. How many grams of zinc sulfate are made?

10. Methyl alcohol (CH3OH) has a density of 0.793 Kg/L. What volume of it is needed to add to water to make twenty-five liters of 0.15 M solution?

11. Magnesium has a density of 1.741 g/cc. What volume of Mg will burn to produce a kilogram of magnesium oxide?

12. What volume of water vapor is produced at 716 mmHg and 87C when 2.6 liters of methyl alcohol burns?

ANSWERS TO PROBLEMS USING COMPLETE ROADMAP

1. 2.99 L

2. 1.10 E3 mL

3. 1.45 E24 atoms

4. 4.67 E5 L

 

 

 

 

5. 1.50 E4 L

6. 0.15 moles

7. 439 g

8. 0.125 M

 

 

 

 

9. 8.44 g

10. 151 mL

11. 0.346 L

12. 1.29 E5 L