1. Chapter 3 Test Review -Two short answer and one word problem for each concept - Test will take while. Start Monday and finish by Wednesday. - Homework for all of chapter one is due before break of else all days will be minimal.
Test Monday 11/24/-11/26

2. Topic 1: Atomic Masses and Mass Spectrometry
Atoms don’t always retain the same weight
Mass of an atom is determined as Protons + Neutrons
With a specific element, protons do not change but neutrons can change
This is called an isotope
*Topic 1 Question
There are three isotopes for neon. How many protons, electrons, and neutrons a
20Ne, 21Ne, and 22Nere there for each isotope?

3. Topic 1: Atomic Masses and Mass Spectrometry
*Topic 1 Question: Element E occurs in two isotopes. 15% of all atoms of E have a relative atomic mass of and the rest a relative atomic mass of What is the average relative atomic mass for the element E? What element might E be? Draw a mass spec for element E

4. Topic 2: Molar Mass One mole of anything is 6.02X1023
A mole is defined as the amount of atoms in 12 grams of Carbon
*Topic 2 Question:
1) How many grams are in 1 mole of aluminum?
II) Based on this, what do you think is the most common isotope of aluminum?
III) What is the molar mass of ammonium phosphite?

5. Topic 2: Molar Mass
*Topic 2 Question: How many atoms are in 6.4 micrograms of Au?

6. Topic 3) Percent Composition
Percent composition is calculated by finding the percent of each atom in a compound.
*Topic 3 Question
1) What is the percent composition of each atom in ammonium dihydrogen phosphate?
II) On an AP test 2 years ago, the test asked for “decimal notation.” Answer the above question in decimal notation. Don’t let the wording trick you.

7. Topic 4: Empirical and Molecular Formulas
Empirical formula is a formula in lowest terms. While molecular formula is “real” formula.
*Topic IV Questions
I) What is the empirical and molecular formula of water?
II) What is the empirical and molecular formula of hydrogen peroxide?
III) What is the empirical and molecular formula of glucose?

8. Topic 4: Determine Empirical and Molecular Formulas for a Compound
This is how you determine empirical and molecular formulas. You will be given the percent composition to determine the empirical formula and the atomic mass IF they want you to determine the molecular formula
Step 1) Turn mass percent into grams. Hence you now have a 100 gram sample
Step II) Calculate the amount of moles of each type of element in the 100 gram sample
Step III) Divide of the total amount of moles by the lowest number of moles determined
Step IV) Make sure each number is a whole number (you may have to multiple by 2. This is now the EMPIRICAL FORMULA for the compound.
Step V) To find molecular formula, divide the GIVEN molar mass of the molecular formula but the molar mass of the empirical formula (you must calculate)
Step VI) Multiple the empirical formula by the number found in the step above. Remember this must be a whole number.

9. Topic 4: Determine Empirical and Molecular Formulas for a Compound
*Topic 4 Question Caffeine has an elemental analysis of 49.48% carbon, 5.190% hydrogen, 16.47% oxygen, and 28.85% nitrogen. It has a molar mass of g/mol. What is the molecular formula of caffeine?

10. Topic 5: Chemical Equations
Write the chemical equations from the words. Include whether each substance is a solid (s), liquid (l), gas (g) or a dissolved salt in water which means aqueous (aq)
Reactants  Products
After you write out the equation, make sure each side is balanced

11. Topic 5: Chemical Equations
*Topic 5 Question Calcium hydroxide aqueous solution reacts with phosphoric acid to yield calcium phosphate precipitate and water. Determine the balanced equation.

12. Topic 6: Reaction Stoichiometry
Balance both sides of the equation
Know how to do mole ratios between products and reactants
*Topic 6 Question
What is the mole ratio of hydrogen gas to oxygen gas?
What is the mole ratio of hydrogen gas to water?
What is the mole ratio of oxygen gas to water?

13. Topic 6: Reaction Stoichiometry
CaCO3+2HCl->CaCl2+H2O+CO2
*Topic 6 Questions
1) 5.00 grams of calcium carbonate in excess hydrochloric acid produces how much carbon dioxide?
II) How many moles of hydrochloric acid is needed to produce 3.45X1012 molecules of calcium chloride?
III) How many moles of calcium carbonate was asses if 12 grams of water was formed?

14. Topic 7: Limiting Reactants and Percent Yields
*Topic 7 question
How many grams of NH3 can be produced (theoretically) from the reaction of 5.0 g of nitrogen gas and 5.0g of hydrogen gas?
Note: you must first determine the limiting reagent?

15. Topic 7: Limiting Reactants and Percent Yields
*Topic 7 question
If 8.52 g are actually formed, what is the percent yield of NH3?