Stoichiometry Study Guide

“The quantity of matter is the measure of the same, arising from its density and bulk conjointly.”

Einstein, Principia, page 1

Unit Test: Week of 4/6/14

Essential Questions:

  • How much does an atom weigh?
  • How do you figure out a substances empirical formula?
  • How do I figure out how much reactant I need?
  • How do I figure out how much product I get?
  • What is a limiting reagent?
  • What is always conserved in a chemical reaction?

Vocabulary: Must know vocabulary!

anhydrous salt / formula mass / molecule
atom / formula unit / molecular formula
atomic mass / gram formula mass / molecular mass
Avogadro’s number / gram molecular mass / percent composition
dimensional analysis / hydrate / representative particles
compound / hydrated salt / STP
element / ion / volume
empirical formula / molar mass / percent yield
actual yield / gram formula mass / significant figures
experimental yield / Law of Conservation of Mass / mass calculation
balanced equation / mass / skeleton equation
chemical reaction / molar mass / theoretical yield
conserve / molar volume @ STP / evaporating dish
constant mass / mole ratio / mole

Formulas:

Avogadro ’s number (NA) = 6.02 x 1023

1 mole = 6.02 x 1023

1 mole of gas = 22.4 L of gas at STP (Standard Temperature and Pressure)

1 mole of substance = mass calculated from periodic table

Textbook Connections:

Chapter 10 / Chemical Quantities / pages 286-319
Chapter 12 / Stoichiometry / pages 352-383

If you need additional practice problems, complete the problems that show the answer in Appendix E so that you can check your answers. If you do problems that do not have an answer in Appendix E, see Mrs. Culbertson to check your answers.

Extension Activities:Choose 2of the following questions, complete, and turn in the day of the unit test (or before if you finished early for 2 extra credit points). Your grade will be reduced one letter grade each day it is late. Be sure to identify the number of the question you are answering. You cannot use a homework pass for this assignment. Please neatly list your answers.

  1. Inside the airbag is a gas generator containing a mixture of NaN3, KNO3, and SiO2. When the car undergoes a head-on collision, a series of three chemical reactions inside the gas generator produce gas (N2) to fill the airbag and convert NaN3, which is highly toxic (The maximum concentration of NaN3allowed in the workplace is 0.2 mg/m3air.), to harmless glass. Visit the following website and answer the questions below.
  2. Write and balance the 3 reactions that occur when an airbag is deployed.
  3. How many grams of sodium azide is required to inflate an airbag to 67 L at STP (assume this requires 67L of the gas)?
  4. Based on the amount of sodium azide required from 1b, what mass sodium is produced?
  5. How many grams of potassium nitrate are needed to completely react with the sodium? (use balanced equation form #13).
  6. Use at least 15 words from the list of vocabulary on the front of this page in a comprehensive essay. Each word must be used in the proper context and used in a manner to explain Stoichiometric concepts. Underline the words that you use (words that are not underlined will not be graded).
  7. **This option counts as two activities** Hydrogen, nitrogen, oxygen, fluorine, chlorine, and all of the noble gases are in the gaseous state at 25°C.
  8. Choose one gas from the list above.
  9. What volume does 1 mole of your gas occupy at STP?
  10. Build a cardboard or paper box that could hold exactly 1M of your element at STP.
  11. Decorate the box. Be sure to include the calculation from 3b, facts about your gas, and calculations for deriving the box’s dimensions.
  12. Sodium carbonate is one of two key ingredients in making thousand year old eggs, a Chinese delicacy. The sodium carbonate breaks down the egg white into simpler, tastier molecules such as ammonia, fatty acids and hydrogen sulfide.
  13. What is the molar mass of sodium carbonate?
  14. One recipe calls for 100 grams of sodium carbonate. How many moles of sodium carbonate does this represent?
  15. How many grams of sodium are present in 100 grams of the compound?
  16. Every month a water quality analysis is performed. The table below lists the results for May 2006. Quantities are recorded as micrograms (ug) or milligrams (mg) in a liter of drinking water. Use the table below to answer the following questions.

Water Supply Trace Materials
Aluminum / <15.0 / ug/l / Fluoride / < 0.02 / ug/l
Ammonia / <0.01 / mg/l / Iron / 11.6 / ug/l
Antimony / <1.0 / ug/l / Lead / <1.2 / ug/l
Arsenic / <1.0 / ug/l / Magnesium / 504 / ug/l
Barium 7.1 / 7.1 / ug/l / Manganese / 4.7 / ug/l
Beryllium / <0.3 / ug/l / Mercury / 0.01 / ug/l
Bromide / 9.5 / ug/l / Nickel / <5.0 / ug/l
Cadmium / 0.5 / ug/l / Nitrate / 0.005 / mg/l
Calcium / 2070 / ug/l / Potassium / 478 / ug/l
Chloride / 7.8 / mg/l / Silica (SiO2) / 2180 / ug/l
Cyanide / <0.01 / ug/l / Sodium / 4.9 / mg/l
  1. How many atoms of arsenic are present in one liter of water?
  2. How many moles of silicon dioxide (sand) are present in one liter of water?
  3. Are there more moles of potassium or manganese per liter?