UNIT 9 Stoichiometry
FORMULA MASS Atomic Mass Unit (u): unit of mass for measuring atoms. (1 u = 1/12 th the mass of a carbon 12 atom)
FORMULA MASS
FORMULA MASS Example 2: Find the mass of one molecule of Acetic acid (HC 2 H 3 O 2 ).
FORMULA MASS Example 3: Find the formula mass of on molecule of magnesium phosphate.
FORMULA MASS Example 4: Find the mass of one molecule of copper (II) sulfate pentahydrate.
PERCENT COMPOSITION
PERCENT COMPOSITION Example 2: What is the percent composition by mass of magnesium in Mg 3 (PO 4 ) 2?
PERCENT COMPOSITION Example 3: What is the percent by mass of water present in 1.0 mol of MgCl 2 6H 2 O
PERCENT COMPOSITION Example 4: A student obtained the following data to determine the percent by mass of water in a hydrate. Mass of empty crucible + cover.15.5 g Mass of crucible + cover + hydrated salt.18.3 g Mass of crucible + cover + anhydrous salt..17.8 g Calculate the percent by mass of the water in the hydrated salt.
EMPIRICAL & MOLECULAR FORMULAS Formula that gives the simplest whole number ratio of atoms of elements in a compound Complete formula of a molecule NOT reduced
EMPIRICAL & MOLECULAR FORMULAS Example 1: Circle the empirical formulas in the list below; put an X over the molecular formulas. C 2 H 4 HCl CH 4 NO 2 C 3 H 9 C 5 H 9 PCl 4 P 2 O 4 C 6 H 12 O 6 C 12 H 22 O 11
EMPIRICAL & MOLECULAR FORMULAS Example 1: Circle the empirical formulas in the list below; put an X over the molecular formulas. C 2 H 4 HCl CH 4 NO 2 C 3 H 9 C 5 H 9 PCl 4 P 2 O 4 C 6 H 12 O 6 C 12 H 22 O 11
EMPIRICAL & MOLECULAR FORMULAS Example 2: For the following, give the empirical formula. N 2 O 4 C 6 H 12 O 6 C 4 H 8 O 2 C 3 H 9 C 5 H 20 C 2 H 4
EMPIRICAL & MOLECULAR FORMULAS Example 2: For the following, give the empirical formula. N 2 O 4 C 6 H 12 O 6 C 4 H 8 O 2 C 3 H 9 C 5 H 20 C 2 H 4
EMPIRICAL & MOLECULAR FORMULAS Example 3: A compound has the empirical formula of NO2. If the molecular mass of this compound is 138.0 g/mol, what is the molecular formula of the compound?
EMPIRICAL & MOLECULAR FORMULAS Example 4: A compound has a molar mass of 120 g/mol and an empirical formula of CH 2 O. What is the molecular formula of this compound?
THE MOLE Reflect: What do the terms dozen, gross, and ream have in common?
THE MOLE Mole: Amount of substance Stands for a number = 6.02 x 10 23 (just as a dozen = 12, a gross = 144, etc) The mole allows us to compare numbers of particles (which may have different masses)
THE MOLE A mole of donuts = 6.02 x 10 23 donuts A mole of baseballs = 6.02 x 10 23 baseballs A mole of jelly beans = 6.02 x 10 23 jelly beans
TED TALK: HOW BIG IS A MOLE? http://www.wimp.com/howbig/
THE MOLE
THE MOLE
THE MOLE
THE MOLE
MOLE MOLE Reflect: If it takes 2 pieces of bread, 1 piece of cheese, 1 piece of ham, and 3 pieces of lettuce to make one sandwich 2 Bread + 1 Cheese + 1 Ham + 3 Lettuce 1 Sandwich How many sandwiches could I make with 4 pieces of bread? How many pieces of cheese would I need to use up 6 slices of bread?
MOLE MOLE
MOLE TO MOLE Practice Problem 1: In the following equation, how many moles of HCl are needed to react with 2.3 moles of Zn? 2HCl + Zn --------> ZnCl 2 + H 2
MOLE TO MOLE Practice Problem 2: In the following equation, how many moles of oxygen are needed to burn 0.52 moles of magnesium? 2 Mg + O 2 -----------> 2 MgO
MOLE TO MOLE Practice Problem 3: How many moles of Al(NO 3 ) 3 will be produced when 0.75 mole of AgNO 3 reacts according to the following equation: AgNO 3 + Al --------------> Al(NO 3 ) 3 + Ag
MOLE CONVERSIONS: 1 - STEP Reflect: How many seconds are in 2 minutes? What did you need to solve that problem?
MOLE CONVERSIONS: 1 STEP
MOLE CONVERSIONS: 1 - STEP The Mole 1 mole = Gram Formula Mass 1 mole = 6.02 x 10 23 1 mole = 22.4 Liters of a gas The mole establishes the relationship between the gram and atomic mass unit.
MOLE CONVERSIONS: 1 - STEP Directions: Complete each of the following mole conversions showing your work and labeling ALL numbers! Example 1: If you have 11.2 g of NaCl, how many moles do you have?
MOLE CONVERSIONS: 1 - STEP Example 2: How many grams are in 2.50 moles of NaCl?
MOLE CONVERSIONS:1 - STEP Example 3: How many molecules in 2 moles of water? Example 4: How many moles are in 1.81 x 10 24 formula units of zinc nitrate?
MOLE CONVERSIONS: 1 - STEP Example 5: How liters are in 4 moles of carbon dioxide gas? Example 6: How many moles are in 56 liters of ammonia gas?
MOLE CONVERSIONS: 1 - STEP Avogadro s Law: Equal volumes of a gas will contain the same number of particles. 1 mole of any gas = 22.4 Liters (molar volume)
MOLE CONVERSIONS: 2 - STEP Reflect: Look at the mole map in your notes. If I want to find out how many atoms are in a ten gram piece of copper wire, how many steps must I take?
MOLE CONVERSIONS: 2 STEP Example 1: How many grams are in 7.2 x 10 22 atoms of Ca?
MOLE CONVERSIONS: 2 STEP Example 2: How many sucrose molecules in 250 grams of sucrose? (Sucrose = C 12 H 22 O 11 )
MOLE CONVERSIONS: 2 STEP Example 3: What is the volume of 4.00 x 10 24 molecules of methane (CH 4 )?
MOLE CONVERSIONS: 2 STEP Example 4: What is the mass of 64.5 liters of oxygen gas?
MOLE CALCULATIONS: 2 STEP Example 5: How many grams are in 13 L of carbon dioxide?
MOLE CALCULATIONS: 2 STEP Example 6: What is the volume, in liters, of 35.6 g of NH 3?