Ch. 8 Stoichiometry

Title and Highlight Right Side – NOTES ONLY TN Ch 8.1 Date Topic: EQ: Book Questions: Write Question out (left side of red line) and answer it (Highlight answer) based on from what you read. Notes: Write out the notes from my website. You may use different color pens. Use Bullets or Number notes. Space out your notes so you can add any additional into during lecture. NO HIGHLIGTING, UNDERLINING, etc WE WILL DO OUR FOCUS NOTES TOGETHER Summary: Write 2-3 sentences (end of notes) from what you learned from reading, notes, and/or lecture.

Title and Highlight LEFT Side – PICTURES, PRACTICE PROBLEMS, ETC TN Ch 8.1 DRAW ANY PICTURES, FIGURES, AND WRITE OUT ANY PRACTICE PROBLEMS/QUESTIONS. WE WILL ANSWER THEM TOGETHER. LEAVE SPACES SO WE CAN ANSWER QUES.

Ch. 8.1-8.3 Topic: Stoichiometry EQ: What is a mole ratio and how is it used in conversions? READ Ch 8.1-8.3 (pg. 249-253) Write Questions & Answer Questions #1, 2a, 3 (notes side) Highlight answer

Stoichiometry refers to the numerical relationship between chemical quantities in a balanced chemical equation.

What are the “mole ratios” in this equation? Interpreting Chemical Equations The first thing that must be done is to ______________ the equation! ___N2 (g) + ___H2 (g)  ___NH3 (g) What are the “mole ratios” in this equation? Here are the kinds of information you can get from the equation: ____ mole N2 + ____ moles H2  ____ moles NH3 ____ molecules N2 + ____ molecules H2  ____ molecules NH3 balance 1 3 2 MOLE RATIOS!! 1 3 2 2 1 3

Stoichiometry Conversion Chart Don’t draw – you already have a copy Stoichiometry Conversion Chart Mass A Mass B Molar Mass Molar Mass Avogadro’s # Avogadro’s # Particles A Mole A Mole Ratio Mole B Particles B Count them Count them Count them Molar Volume Molar Volume Count them mole a mole b Atoms/Ions in A Volume A Volume Ratio Volume B Atoms/Ions in B

Mole to Mole Conversions The conversion factor is the mole ratio. The mole ratio comes from the _________________ of the balanced chemical equation. Step 1: Write down the known (A) and unknown (B). Step 2: Set up a mole ratio to change from moles A to moles B coefficients

Practice Problems: N2 (g) + 3H2 (g)  2NH3 (g) Left side - Leave about 5 spaces between each problem Practice Problems: N2 (g) + 3H2 (g)  2NH3 (g) How many moles of ammonia can be made from 7 moles of nitrogen reacting with an excess of hydrogen? How many moles of hydrogen are required to completely react with 8 moles of nitrogen to produce ammonia? How many moles of hydrogen are needed to react with an excess of nitrogen to make 10 moles of ammonia?

Ch. 8.4 Topic: Mole to Mass Conversion EQ: How are mole ratios used in mole-mass conversions? READ Ch 8.4 (pg. 253-257) Write Questions & Answer Questions #4 (notes side) Highlight answer

Practice Problem: CaH2 (s) + 2H2O (l)  Ca(OH)2 (aq)+ 2H2 (g) Left side - Leave about 5 spaces between each problem Practice Problem: CaH2 (s) + 2H2O (l)  Ca(OH)2 (aq)+ 2H2 (g) What mass of calcium hydroxide will be produced from the reaction of 2.50 mol of calcium hydride with excess water? (another product is hydrogen gas) 2. What mass of water is needed?

Mass-Mass Conversion Problems Mass-Mass: (mass A to moles A to moles B to mass B) Step 1: Write down the known (A) and unknown (B). Step 2: Convert from mass A to moles A Step 3: Convert from moles A to moles B using a mole ratio. Step 4: Convert from moles B to mass B.

Left side - Leave about 5 spaces between each problem Practice Problem: 3. How many grams of ammonia can be made from reacting 39.0 grams of nitrogen with an excess of hydrogen? N2 (g) + 3H2 (g)  2NH3 (g)

Ch. 8.5 Topic: Limiting and Excess Reactants EQ: What is the difference between L.R. and E.R.? ***BONUS QUESTION ON EXAM*** READ Ch 8.5 (pg. 257-260) Write Questions & Answer Questions #7 (notes side) Highlight answer

Limiting Reagent (or Limiting Reactant) The limiting reagent is a REACTANT that _________ _____ first. Once the limiting reagent runs out, the rxn stops!! The reactant that is in abundance (reactant that you have too much of) is called the ___________ reagent. runs out excess

To summarize: • Limiting reactant (or limiting reagent)—the reactant that is completely consumed in a chemical reaction. You run out of this reactant first and it stops the rxn. Once you determine LR, that chemical starts every calculation especially THEORETICAL YIELD of product • Excess Reactant— the reactant you have too much of and have leftovers not being used in the rxn.

Practice Problem #1 2Na(s) + Cl2(g)  2 NaCl(s) Left side - Leave about 10 spaces between each problem Practice Problem #1 2Na(s) + Cl2(g)  2 NaCl(s) Know: 53.2 g Na and 65.8 g Cl2 Find: limiting reactant & theoretical yield of NaCl

Cu2O(s) + C(s)  2 Cu(s) + CO(g) Left side - Leave about 10 spaces between each problem Practice Problem #2 Cu2O(s) + C(s)  2 Cu(s) + CO(g) Given: 11.5 g Cu2O and 114.5 g C Find: limiting reactant & theoretical yield of Cu

Ch. 8.6 Topic: Percent Yield EQ: How do you calculate % yield from actual and theoretical yields? READ Ch 8.6 (pg. 260-264) Write Questions & Answer Questions #8 - 9 (notes side) Highlight answer

Percent Yield You can calculate this amount using stoichiometry! Percent Yield is a ratio that tells us how ________________ a chemical reaction is. The higher the % yield, the more efficient the reaction is. (How good is your data!!) Actual Yield Theoretical Yield The ___________ yield is the amount you experimentally get when you perform the reaction in a lab. (Your result) The _______________ yield is the amount you are ideally supposed to get if everything goes perfectly. (No errors in lab - what you should have got). You can calculate this amount using stoichiometry! efficient % Yield = x 100 actual theoretical

Actual Yield and Percent Yield The Percent yield is always less than 100%. Why??? Errors happen. Some of the product does not form.

b. Given: actual yield 86.4 g NaCl (PRODUCT) Find: percent yield Left side - Leave about 10 spaces between each problem Practice Problem #1 USE INFO FROM CH 8.5 TN!! a. Example: 2Na(s) + Cl2(g)  2 NaCl(s) Given (grams): 53.2 g Na and 65.8 g Cl2 Find: limiting reactant and theoretical yield of NaCl. b. Given: actual yield 86.4 g NaCl (PRODUCT) Find: percent yield

Find: limiting reactant and theoretical yield of Cu Left side - Leave about 10 spaces between each problem Practice Problem #1 USE INFO FROM CH 8.5 TN!! a. Example 8.6: Cu2O(s) + C(s)  2 Cu(s) + CO(g) Given (grams): 11.5 g Cu2O and 114.5 g C Find: limiting reactant and theoretical yield of Cu b. Given: actual yield 87.4 g Cu Find: percent yield