grams atomic weight moles 1 mole = 6.02 x 10 23

Transcription

1 Notes Page - balancing chemical equations (WS 4.1) 1) H 2 + O > H 2 O 2) Fe + O > Fe 2 O 3 3) C 3 H 8 + O > CO 2 + H 2 O 4) H 2 O > H 2 O + O 2 5) P 4 + Br > PBr 3 6) Fe 2 S 3 + C -----> Fe + CS 2 Notes Page - converting grams to moles to molecules (WS 4.2) grams atomic weight moles 1 mole = (g/mol) 6.02 x atoms/ molecules moles of is how many grams? grams of is how many moles? moles of is how many atoms? x 1024 molecules of is how many grams? 5. How many molecules are in 87.0 grams of?

2 Stoichiometry - day 1 (WS 4.4) 4 Fe + 3 O 2 ---> 2 Fe 2 O 3 1) How many moles of Fe 2 O 3 can be produced from 6.92 moles of O 2? 2) How many moles of Fe 2 O 3 can be produced from 5.30 grams of O 2? 3) How many grams of Fe are needed to react with 21.5 grams of O 2? Stoichiometry - day 2 The amount of product you can theoretically make during a chemical reaction is called the In a chemical reaction, the reactant which you run out of 1st is called the In a chemical reaction, the reactants which are left-over are called The amount of product you actually make after a chemical reaction is called the The efficiency of the reaction, calculated by taking (actual theoretical x 100) is called the Packet #4 Objectives: (know these for quiz) balance equations (WS 4.1) convert grams --> moles --> molecules (WS 4.2) use stoichiometry (mole shuffle) to calculate amt. of reactants and/or products needed (WS 4.4) use stoichiometry to calculate theoretical yields & limiting reactants (WS 4.5) predict the products of various types of reactions (WS 4.7) -- this includes knowing the 7 diatomic gases and how to write chemical formulas (WS 2.6 & 3.1) the chemical reaction you did in the 'penny lab' (penny lab) the metal we used in the lab "evidence of a chemical change" (see lab) calculate the % composition by mass for formulas (WS 4.6 top half) calculate the empirical formula given % composition (WS 4.6 bottom half) the idea behind the Micro-Rockets demo (how to find proper "fuel : oxygen" ratio) the products which were produced during the lab "baking soda stoichiometry"

3 N2 + 3 H2 ---> 2 NH3 Stoichiometry, In-Class Practice Problems (WS 4.5) 1. How many moles of each reactant & product are indicated by the equation? moles N2: moles H2: moles NH3: 2. How many grams of each reactant & product are indicated by the equation? grams N2: grams H2: grams NH3: 3. You have 56g of N2 and 30g of H2... a. Which ingredient will be the limiting reactant? b. Which reactant will be in excess? c. How much excess reactant will be left over? d. How much NH3 will be produced (theoretical yield)? e. If the amount of H2 doubled, how much NH3 could be produced? C + O2 ---> CO2 1. How many moles of each reactant & product are indicated by the equation? moles C: moles O2: moles CO2: 2. How many grams of each reactant & product are indicated by the equation? grams C: grams O2: grams CO2: 3. You have 96g of C and 96g of O2... a. Which ingredient will be the limiting reactant? b. Which reactant will be in excess? c. How much excess reactant will be left over? d. How much CO2 will be produced (theoretical yield)? e. If the amount of O2 doubled, how much CO2 could be produced? 6 Na + N2 ---> 2 Na3N 1. How many moles of each reactant & product are indicated by the equation? moles Na: moles N2: moles Na3N: 2. How many grams of each reactant & product are indicated by the equation? grams Na: grams N2: grams Na3N: 3. You have 276g of Na and 84g of N2... a. Which ingredient will be the limiting reactant? b. Which reactant will be in excess? c. How much excess reactant will be left over? d. How much Na3N will be produced (theoretical yield)? e. If the amount of N2 doubled, how much Na3N could be produced?

4 Empirical Formula, Example Problems: (WS 4.6.2) #1. An unknown substance is analyzed by a mass spectrometer, and found to be composed of: 44.7 % P rest % O Determine its empirical formula Demo, Dehydration of Sugar. What is the reaction which takes place in this demo? #2. An unknown substance is analyzed by a mass spectrometer, and found to be composed of: 52.2 % C 13.0 % H rest % O Determine its empirical formula

5 In-Class Practice Problems: Types of Reactions Combustion- occurs when a fuel (which contains carbon, hydrogen, and sometimes oxygen) burns. This reaction requires oxygen. The 2 products are always carbon dioxide and water. fuel + O 2 ---> CH 4 + O 2 ---> try this: C 6 H 12 O 6 + O 2 ---> Synthesis (Composition)- occurs when two simple elements combine to form a compound. Al + S ---> H2 + Cl2 ---> K + N2 ---> Decomposition- occurs when a compound splits apart into simple elements. FeCl3 ---> HgS ---> N2O ---> Single Replacement- occurs when a lone metal switches places with a metal in a compound. *** This will only occur if the lone metal is higher on the activitity series than the metal it's trying to replace. Al + FeCl2 ---> Fe + AlCl3 ---> Mg + CrCl3 ---> Cu + H2SO4 ---> Pb(NO 3 ) 4 + Zn ---> Al + Fe 2 O 3 ---> Double Replacement- two metals in a compound switch places. CaCl2 + NaOH ---> Li3PO4 + MgCl2 ---> Li K Ca Na Mg Al Mn Zn Cr Fe Cd Co Ni Sn Pb H Cu Hg Ag Pt Au AlBO3 + NaCN --->

6 Micro-Rockets Notes Page 1. How is the hydrogen gas created? (What is the chemical reaction?) 2. What is the chemical reaction which occurs when the rocket is launched? 3. For optimal results, what is the correct ratio of fuel to oxygen (H 2 : O 2 )? 4. Suppose someone wanted to make a methane (CH 4 ) rocket... What would be the correct reaction & the correct ratio of fuel to oxygen (CH 4 : O 2 )? 5. Suppose someone wanted to make an ethanol (C 2 H 6 O 2 ) rocket... What would be the correct reaction & the correct ratio of fuel to oxygen? 6. Suppose someone wanted to make a gasoline (C 8 H 18 ) rocket... What would be the correct reaction & the correct ratio of fuel to oxygen?