1 Name: Date: Period: Project Description: In this project, you will be ...

Chemical Changes on a Molecular LevelLet’s look at the chemical reaction of magnesium and oxygen.http://www.youtube.com/watch?v=m2i9jLPXprQDescribe what magnesium ribbon looks like:Describe what oxygen looks like:Describe what magnesium oxide (MgO) looks like:Let’s look at the chemical equation for the reaction:2 Mg (s) + O 2 (g) ----> 2 MgO(s)On a molecular level, chemical changes occur when….3

Homework4

Mostly Cloudy Mini-Lab1.) Put on googles.2.) Label 1 plastic cup “water” and 1 plastic cup “limewater.”3.) Measure out 5 mL of water and pour it into the cup labeled “water.”4.) Measure out 5 mL of limewater and pour it into the cup labeled “limewater.”5.) Add 5 mL of carbonated water into each cup. Observe what happens.Fill out this data table:MaterialsWater + carbonated waterObservationsLimewater + carbonated waterJournal: In which cup did you think a chemical reaction occurred? What evidence supports your conclusion?7

HomeworkStoichiometry Reflection #2Please type up your answers using size 12, Times New Roman, double-spaced font. You should be thorough andcomplete in answering all of these questions. Please email me your answers when you are done.1.) What experiments or reactions did you like doing today in class? Why?2.) What are some ways to tell if a chemical reaction or change has happened?3.) What lessons did you learn from the “Mostly Cloudly Mini-Lab?” Which chemicals had a reaction? Which chemicalsdid not? How do you know?4.) Look at the following pictures and explain how you know a chemical reaction occurred for each picture:Picture #1: Picture #2:

STEP 3: EVIDENCE FOR CHEMICAL REACTIONS (EXO & ENDOTHERMIC REACTIONS)Journal: We’ve already learned a couple of ways to identify whether a chemical reaction has occurred or not. What aresome signs that show us whether a chemical reaction has occurred or not?One more way to see whether a chemical reaction has occurred or not is from ________________________________***NOTE: every chemical reaction needs some energy to get started. We call this energy the ____________________.Picture APicture BThere are 2 types of reactions:Some reactions __________________________ while others ______________________________________________.1.2.9

Evidence For Chemical Reactions LabAdapted from http://www.middleschoolscience.com/bag.htmObjective: In this lab, you will be observing a couple of chemical reactions andfinding ways to describe how you know chemical reactions have actuallyoccurred.Materials: sandwich size zip top bag (x3) 2 plastic spoons 2 tbsp calcium chloride (x3) 2 Tbsp. baking soda (x3)1 test tube of water (x3)30 mL of phenolphthalein (x3)Goggles, gloves, lab apronProcedure Bag 1:1. Place 2 tsp of baking soda into the bag.2. Add 30 mL of Phenolphthalein to the bag.3. Massage the bag to mix the contents.4. VERY CAREFULLY - lower the test tube containing 30 mL of water upright into the bag. Do not let any spill out.5. One group member should hold the test tube by squeezing the test tube gently from the outside of the bagwhile another group member squeezes the excess air out and seals the bag.6. Hold the test tube and bag up and slowly spill the water out of the test tube (while the bag is still sealed).Observe the reaction and record what you see and feel happening in the data section.7. Pass the bag around and let all group members look at and feel the contents of the bag.Procedure Bag 2:1. Place 2 tsp of calcium chloride into the bag.2. Add 30 mL of Phenolphthalein to the bag.3. Massage the bag to mix the contents.4. VERY CAREFULLY - lower the test tube containing 30 mL of water upright into the bag. Do not let any spill out.5. One group member should hold the test tube by squeezing the test tube gently from the outside of the bagwhile another group member squeezes the excess air out and seals the bag.6. Hold the test tube and bag up and slowly spill the water out of the test tube (while the bag is still sealed).Observe the reaction and record what you see and feel happening in the data section.7. Pass the bag around and let all group members look at and feel the contents of the bag.Procedure Bag 3:1. Place 2 tsp of baking soda into the bag.2. Place 2 tsp of calcium chloride.3. Add 30 mL of Phenolphthalein .4. Massage the bag to mix the contents.5. VERY CAREFULLY - lower the test tube containing 30 mL of water upright into the bag. Do not let any spill out.6. One group member should hold the test tube by squeezing the test tube gently from the outside of the bagwhile another group member squeezes the excess air out and seals the bag.7. Hold the test tube and bag up and slowly spill the water out of the test tube (while the bag is still sealed).Observe the reaction and record what you see and feel happening in the data section.8. Pass the bag around and let all group members look at and feel the contents of the bag.10

*****AS PART OF YOUR HOMEWORK, PLEASE EMAIL ME YOUR DATA & OBSERVATIONS SECTION AND THECONCLUSION SECTION.Data & ObservationsFill out the following table for the chemical reaction that you saw happening in each bag.Bag #1What happened withthe color?Werefoam/bubbles/gasproduced?Was there atemperature change?Did it get hotter orcolder or stay thesame?Was this reactionendothermic,exothermic orneither?Bag #2Bag #3ConclusionAnswer the following questions. Please be specific and answer each question completely!1.) In terms of color change, how were the 3 bags similar? How were they different?2.) In terms of foam/bubbles/gas being produced, how were the 3 bags similar? How were they different?3.) In terms of temperature change, how were the 3 bags similar? How were they different?4.) Did a chemical reaction happen in Bag #1? How can you tell?5.) Did a chemical reaction happen in Bag #2? How can you tell?6.) Did a chemical reaction happen in Bag #3? How can you tell?7.) Without opening the bags, how can you tell if a gas was produced or not?8.) The reaction in the 3 rd bag was:2NaHCO 3 + CaCl 2 -----------> CaCO 3 + 2NaCl + H 2 O + CO 2baking soda + calcium chloride calcium carbonateA.) Using this chemical equation, summarize what materials we started off with in this reaction and what materials weended up producing. For example, “We took baking soda (NaHCO 3 ) and mixed it with calcium chloride. They reacted andformed calcium carbonate…..” ---> so finish this sentence….THERE IS MORE ON THE NEXT PAGE – FLIP OVER!11

B.) Using the chemical equation above, what gas was produced in Bag #3?9.) Which reactions in this lab were exothermic? How do you know that they were exothermic?10.) Which reactions in this lab were endothermic? How do you know that they were endothermic?QUESTIONS ON ENERGY GRAPHS FOR CHEMICAL REACTIONSAdapted from http://www.kentchemistry.com/links/Kinetics/PEDiagrams.htm11.) What is activation energy?12.)Given the reaction: A + B --> C. Does the diagram show an endothermic or exothermic reaction? Why or why not?13.) The reaction that forms water is below:2 H 2 (g) + O 2 (g) --> 2 H 2 O(l) + 571.6 kJIn this reaction, one of the products is heat, meaning, heat is released in thisreaction.a.) Is this reaction endothermic or exothermic? Why or why not?b.) Which graph (to the right) is the correct graph to represent the reactionthat forms water? Why did you pick that graph?14.) The diagram below represents a chemical reaction. Use this diagram toanswer the following questions.a.) Is this reaction an endothermic or exothermic reaction? Howdo you know?b.) Which letter represents the activation energy? How do youknow?c.) Using the letters in the diagram (i.e. A, B, C, or D) whatformula would you use to figure out the difference between theenergy of the reactants and the energy of the reactants?d.) Using the letters in the diagram (i.e. A, B, C, or D) whatformula would you use to figure out the amount of activationenergy needed to start the reaction?12

15.) The diagram below represents a chemical reaction. Use the diagram to answer the following questions.a.) How much is the activation energy for this reaction? How did youfind your answer?b.) What is the difference in energy between the reactants and theproducts? How did you find your answer?c.) Is this reaction endothermic or exothermic? How do you know?13

STEP 4: WHAT ARE CHEMICAL EQUATIONS?Journal: When you text, what are some abbreviations you use? What do these abbreviations mean?Chemical Equations are….FormulasWhat do these formulas mean? How many atoms are in each compound?EX:CaCO 3EX:10 CO 2TRY THESE OUT:Formulas1. ) N 2How many molecules(units) are there?Elements/# of atoms per element2.) BaCO 33.) CH 3 COOH4.) H 2 SO 45.) (NO 3 ) 26.) (OH) 37.) (SO 4 ) 38.) Fe 2 (CO 3 ) 39.) (NH 4 ) 3 PO 410.) 2 H 2 O11.) 3 V 2 O 512.) 3 B(OH) 313.) 5 B 2 (SO 4 ) 314.) 2 Be(NO 2 ) 215.) 7 Cu(OH) 214

Structure of an EquationAll chemical reactions follow the same structure.There are 2 main parts:1.2.The general structure is….***NOTE:Dollar Bill Demonstration2 C 3 H 7 OH + 6 O 2 ------> 6 CO 2 + 2 H 2 OReactantsHow many molecules(units) are there?Elements/# of atoms per elementProducts15

Homework1.) What are reactants?2.) What are products?3.) The following chemical reaction is photosynthesis, or the process by which plants make food (sugars). Fill out thetable below based on this chemical reaction.ReactantsHow many molecules(units) are there?Elements/# of atoms per elementProducts16

4.) Fill out the following table based on the chemical formula.Formulas How many molecules(units) are there?Elements/# of atoms per element1. ) C 2 H 4 O 22.) Na 2 O3.) Fe(NO 3 ) 24.) Be(NO 2 ) 25.) Ga 2 (SO 3 ) 36.) 2 NaNO 37.) 4 Li 2 SO 48.) 3 Pb(NO 3 ) 29.) 10 Al 2 (SO 4 ) 317

STEP 5: CONSERVATION OF MASSReview- How many molecules and elements do I have?Formulas How many molecules(units) are there?Elements/# of atoms per element1. ) Fe 2 (SO 4 ) 32.) 3 CH 43.) 3 H 2 (SO 4 )Discover Activity with the coins1.) Sort stacks into pennies, nickels, dimes and quarters. Fill out the table below.coins Pennies Nickels Dimes Quarters TOTAL $amount2.) Now mix them together and make 3 random stacks of these coins. Fill out the table below.coins Pennies Nickels Dimes Quarters TOTAL $amount3.) Mix the coins together again and now stack them into 4 random stacks.coins Pennies Nickels Dimes Quarters TOTAL $amountDescribed what happened in this activity. Did the number of pennies, nickels, dimes and quarters change? Did the totalamount of money change? Why or why not?Conservation of MassWhat did you noticehappening in this picture andwith this chemical reaction?The principle of conservation of mass states that in a chemical reaction….18

Balancing Chemical EquationsBecause of the principle of conservation of mass, there must be …..**THEREFORE, a chemical equation MUST be….STEPS TO BALANCING CHEMICAL EQUATIONS…1.) Write the equation2.) Count the atoms3.) Use the coefficients (numbers in front) to balance the atoms4.) Look back and checkPractice1.)19

2.)3.)4.) Methane gas (CH 4 ) reacts with chlorine gas (Cl 2 ) to form chloroform (CHCl 3 ) and hydrochloric acid (HCl). Balance thisequation.5.) Balance the following equation:___Fe + ___ H 2 (SO 4 ) -------> _____Fe 2 (SO 4 ) 3 + ____H 220

HomeworkFor each problem, balance the chemical equation if needed. If the equation is already balanced, you can just write“equation already balanced.”***Hint: Substitute (NO 3 ) with X21

If you want to check your answers or need help on # 7 – check out this video:http://www.khanacademy.org/video/balancing-chemical-equations?playlist=Chemistry7.)_____Al + _____O 2 ------> _____Al 2 O 38.)_____C 2 H 4 + _____O 2 ------> _____CO 2 + _____H 2 O9.)_____C 2 H 4 + _____O 2 ------> _____CO 2 + _____H 2 O10.)_____C 2 H 6 + _____O 2 ------> _____CO 2 + _____H 2 O11.)_____Fe 2 O 3 + _____H 2 SO 4 ------> _____Fe 2 (SO 4 ) 3 + _____H 2 O22

STEP 6: DIMENSIONAL ANALYSIS PART 1How many seconds are in a year? __________________________Dimensional analysis is a method that is used to _______________________________________________________STEPS TO DIMENSIONAL ANALYSISEX #1 : How many seconds are in day?1.) What are you trying to figure out? What units do you want your answer in?2.) What do you know? (Write down any conversion factors you know).3.) Pick a starting factor4.) Solve – make sure you end with the units you are looking for. Cross off/cancel any units. Multiply across the top andmultiple across the bottom. Then divide.5.) Ask yourself if your answer makes senseEX #2 : How many hours are in year?1.) What are you trying to figure out? What units do you want your answer in?2.) What do you know? (Write down any conversion factors you know).23

3.) Pick a starting factor4.) Solve – make sure you end with the units you are looking for. Cross off/cancel any units. Multiply across the top andmultiple across the bottom. Then divide.5.) Ask yourself if your answer makes senseEx #3: If you are going 50 miles per hour, how many feet per second are you traveling?1.) What are you trying to figure out? What units do you want your answer in?2.) What do you know? (Write down any conversion factors you know).3.) Pick a starting factor4.) Solve – make sure you end with the units you are looking for. Cross off/cancel any units. Multiply across the top andmultiple across the bottom. Then divide.5.) Ask yourself if your answer makes sense24

EX #4: How many seconds are in a year?1.) What are you trying to figure out? What units do you want your answer in?2.) What do you know? (Write down any conversion factors you know).3.) Pick a starting factor4.) Solve – make sure you end with the units you are looking for. Cross off/cancel any units. Multiply across the top andmultiple across the bottom. Then divide.5.) Ask yourself if your answer makes senseEX #5 You're throwing a pizza party for 15 and figure each person might eat 4 slices. How much is the pizza going tocost you? You call up the pizza place and learn that each pizza will cost you $14.78 and will be cut into 12 slices. Youtell them you'll call back. Do you have enough money? Here's how you figure it out, step by step.25

Homework26

1.) How many nickels are in 10 dimes?DIMENSIONAL ANALYSIS PRACTICE DAY 12.) How many dimes are in 5 dollars?3.) How many quarters are in 10 dollars?4.) How many pennies are in 52 nickels?5.) How many dimes are in 20 quarters?27

For the following problems, use the conversion factors.6.) How many miles will a person run during a 10 kilometer race?Conversions Factors1 hr = 60 min 7 days = 1 week24 hrs = 1 day 264.2 gal = 1 cubic meter1 mi = 5,280 ft 20 drops = 1 mL365 days = 1 year 1 L = 1000 mL0.625 mi = 1.00 km 1 L = 1000 cc7.) The moon is 250,000 miles away. How many feet is it from the earth?8.) A family pool holds 10,000 gallons of water. How many cubic meters is this?9.) The average HTHCV student is in class 330 minutes per day. How many hour per day is this? How many seconds isthis?10.) Pepsi puts 355 ml of pop in a can. How many drops is this? How many cubic meters is this?11.) Change 60 miles/ hour to _____ft/sec (clue: both miles and hour must be change to other units)12.) How many seconds are in a year?28

STEP 7: DIMENSIONAL ANALYSIS PART 2Class Practice1.) Jason Biehl raised 60 goats, and then entered into a series of business transactions. He traded all the goats for sheepat an exchange rate of 5 goats for 7 sheep. Next, he exchanged all the sheep for hogs at a rate of 4 sheep for 2 hogsweighing 250 lbs. each. He sold all the hogs at a market price of $55.00 per 100.0 lbs. How much money did he makefrom the 60 goats?2.) How many miles could you drive for $7.90 if the gas mileage of your car is 14 km/liter of gas and the price is$1.29/gal? (1.61 km/mile, 4 qt/gal, 1.1 qt/L)1. Convert the following.a. 0.044 km to metersb. 0.107 g to centigramsc. 15 cm3 to liters1 km = 1000 m1 m = 10 dm1 m = 100 cm1 m = 1000 mm1 m = 10 6 m1 m = 10 9 nm(for meters, grams, andLiters)d. 7.38 g to kilogramse. 6.7 seconds to milliseconds29

2. Convert 112 nm to km.3. What is 10 Kg/mL in units of g/L?4. How many minutes are there in exactly one week?5. How many seconds are in exactly a 40-hr work week?6. Convert 8 hours to seconds.7. An experiment requires that each student use an 8.5 cm length of magnesium ribbon. How many students can do theexperiment if there is a 570cm length of magnesium ribbon available?8. A 1.00 degree increase on the Celcius scale is equivalent to a 1.80 degree increase on the Fahrenheit scale. If atemperature increases by 48.0 °C, what is the corresponding temperature increase on the Fahrenheit scale?9. A chicken needs to be cooked 20 minutes for each pound it weighs. How long should the chicken be cooked if itweighs 4.5 pounds?10. You have a cube with a density of 4.00 g/mL. How much volume would that cube occupy, if it has a mass of 25 g?11. The speed of light is 3.0 x 10 8 m/s. How far could light travel in 6 minutes?30

STEP 8: MOLES & PARTICLESReview: Balance the following equation and write in a complete sentence what this chemical equation is saying._____ CuO + ____C -----> ____ Cu + ____CO 2Description of what this chemical equation is saying:(HINT: CuO = copper oxide)*Unfortunately, this interpretation contains such small quantities of material, so small that you wouldn’t be able tosee the reaction. Scientists came up with a new counting unit called the MOLE1 MOLE (mol) = particles( )Converting From Moles to ParticlesEX: How many gummy bears are 2 mols of gummi bears?EX: How many M&Ms are 5 mols of M&Ms?EX: How many molecules is 2.12 moles of C 3 H 8 (propane)?Converting From Particles to MolesEX: There are approximately 2.43 x 10 46 molecules of water in the Pacific Ocean. How many moles of water is this?EX: The average American drinks 6,000 sodas a year. How many moles of soda is this?EX: How many moles of magnesium is 3.01 x 10 22 atoms of magnesium?31

HomeworkConverting Particles to Moles and Moles to ParticlesMole-Particle Conversions1. How many moles of magnesium is 3.01 x 10 22 atoms of magnesium?2. How many molecules are there in 4.00 moles of glucose, C 6 H 12 O 6 ?3. How many moles are 1.20 x 10 25 atoms of phosphorous?4. How many atoms are in 0.750 moles of zinc?5. How many molecules are in 0.400 moles of N 2 O 5 ?32

STEP 9: MOLES & GRAMSReview:1.) How many molecules are there in 4.0 moles of H 2 O 2 ?2.) Change 7.14 x 10 23 molecules to moles**In a lab, it is too difficult to count out 6.02 x 10 23 particles of a substance every time you want to measure out amole. Instead, you can quickly figure out a mole of a substance by finding its molar mass (or how much 1 mole of asubstance weighs).1 MOLE (mol) =Molar Mass =Finding the Molar Mass of Elements & Compounds1.) C2.) Cu3.) CO 24.) Cu 2 CO 3 (OH) 2Converting Moles to Grams1.) How many grams are 2 moles of oxygen?2.) How many grams are 3.5 moles of water?34

3.) How many grams is 2.4 moles of vinegar (CH 3 COOH)?4.) How many grams is 0.6 moles of salt (NaCl)?Converting Grams to Moles1.) How many moles are in 28 grams of CO 2 ?2.) Find the number of moles of argon in 452 g of argon.3.) Find the grams in 1.26 x 10 -4 mol of HC 2 H 3 O 2.35

HOMEWORKMolar MassDo the following practice problems below.36

STEP 10: MOLES & LITERS (FOR GASES ONLY!!)Review:1.) How many moles is 23 grams of H 2 O?2.) How many grams is 2.5 moles of glucose (C 6 H 12 O 6 )?Mole-Volume RelationshipAvogadro’s hypothesis:Reason for this is….1 MOLE (mol) = liters = particlesWhat this means is….***NOTE: This conversion only applies to gases at standard temperature and pressure(STP) which is…Moles to Volume Conversion1.) Determine the volume, in liters, of 0.60 mol of SO 2 gas at STP.2.) What is the volume of 3.20 x 10 -3 moles of CO 2 at STP.38

3.) At STP, what volume does 0.355 moles of C 2 H 6 occupy or take up?Volume to Moles Conversion1.) How many moles does 44.8 L of Hydrogen gas at STP represent?2.) A sample of oxygen gas occupies 6.2 L at STP. How many moles does that represent?3.) How many moles of neon would occupy 450 mL at STP? (1000 mL = 1 L)39

HomeworkMoles to VolumeComplete the following problems below:40

Mole-Volume Conversions1. Determine the volume, in liters, occupied by 0.030 moles of a gas at STP.2. How many moles of argon atoms are present in 11.2 L of argon gas at STP?3. What is the volume of 0.05 mol of neon gas at STP?4. What is the volume of 1.2 moles of water vapor at STP?41

STEP 11: MIXED MOLE PROBLEMS & MOLE ROAD MAPMixed Mole ProblemsGiven unit Moles Desired unit1. How many oxygen molecules are in 3.36 L of oxygen gas at STP?2. Find the mass in grams of 2.00 x 10 23 molecules of F 2 . 12.624 g3. Determine the volume in liters occupied by 14 g of nitrogen gas at STP.4. Find the mass, in grams, of 1.00 x 10 23 molecules of N 2.42

5. How many particles are there in 1.43 g of a molecular compound with a grammolecular mass of 233 g?4. Aspartame is an artificial sweetener that is 160 times sweeter than sucrose (table sugar) when dissolved in water. Itis marketed by G.D. Searle as Nutra Sweet. The molecular formula of aspartame is C 14 H 18 N 2 O 5 .a) Calculate the gram-formula-mass (molar mass) of aspartame.b) How many moles of molecules are in 10 g of aspartame?c) What is the mass in grams of 1.56 moles of aspartame?d) How many molecules are in 5 mg of aspartame?e) How many atoms of nitrogen are in 1.2 grams of aspartame?43

STEP 12: STOICHIOMETRY PART 1Chemical equations and molar masses are useful to know when trying to figure out the amount of materials you need toproduce something. We will use stoichiometry, which is the study of the relationship between materials in a chemicalequation, to help us figure out the amounts of materials we need or the amount we will receive in a chemical reaction.For example, below is a chemical reaction or recipe that I use to make sandwiches2 breads + 1 cheese + 1 tomato + 3 pickles ---> 1 sandwichUSE DIMENSIONAL ANALYSIS TO ANSWER THESE QUESTIONS1.) If I want to make 1 sandwich, how many pickles do I need? _________________Conversion unit:Solve:2.) If I want to make 3 sandwiches, how many pieces of bread do I need? ____________Conversion unit:Solve:3.) If I have 3 tomatoes, how many sandwiches can I make? ____________Conversion unit:Solve:4.) If I have 9 pieces of bread, how many sandwiches can I make? ____________Conversion unit:Solve:44

Example #1: Now, try with a real chemical reaction.EX: Hydrogen reacts with oxygen to give us water.____H 2 (g) + ____O 2 (g) ------> ____H 2 O(l)1.) First, ALWAYS make sure the equation is balanced. If it isn’t, please balance it. (Otherwise, the rest of your answerswill be incorrect.2.) In this reaction, if I have 1 molecule of O 2 , how many molecules of H 2 do I have? _________How many molecules of water (H 2 O) do I have? _____________3.) In this reaction, if I have 2 moles of H 2 , how many moles of O 2 do I have? __________How many moles of water (H 2 O) do I have? __________4.) If I want to make 6 moles of H 2 O, how many moles of H 2 do I need? __________How many moles of O 2 do I need? ____________5.) Oftentimes in a lab setting, you will have to convert from moles to grams because the only way to measure outmoles is to weigh them with a balance. Using the chemical equation or recipe, I want you to convert the moles intograms.H 2 :O 2 :H 2 O:6.) If I want to form 200 grams of H 2 O, how many moles of H 2 do I need? How many grams of H 2 is that?7.) If I want to form 200 grams of H 2 O, how many moles of O 2 do I need? How many grams of O 2 is that?45

Example #2The chemical reaction for producing pure copper (refining copper) is below. CuO = copper oxide2 CuO (s) + C(s) -----> 2 Cu(s) + CO 2 (g)___moles ___moles ___moles ___moles1.) Is this reaction balanced? How do you know?2.) Write down the amount of moles you see for each reactant and product under the equation.3.) A refiner needs to convert 955.0 g of CuO to pure Cu. What mass of C is needed for this reaction?***Remember, you need to convert to moles in order to use the chemical equation or the recipe!HOMEWORK Complete the problems below on a SEPARATE piece of paper!46

STEP 13: STOICHIOMETRY PART 21.) Balance the chemical equation 2.) convert to moles to use the recipe 3.) convert back to the unitsthat you need1. Given the unbalanced decomposition reaction of baking soda:NaHCO 3 (s) + heat ===> Na 2 CO 3 (s) + CO 2 (g) + H 2 O (g)NaHCO 3 = baking soda/sodium bicarbonateNa 2 CO 3 = sodium carbonateHow many grams of sodium carbonate (Na 2 CO 3 ) are produced by the decomposition of 42.0 grams of baking soda?What volumes of carbon dioxide and water are produced at STP?2. The catalytic decomposition of hydrogen peroxide (H 2 O 2 ) is:H 2 O 2 (aq) ===> H 2 O (l) + O 2 (g)Balance the reaction. How many moles of water and oxygen are produced by the decomposition of 68.0 grams ofhydrogen peroxide? How many molecules (particles) of water are produced? How many grams of oxygen areformed?3. If 156.0 grams of potassium metal reacts with water, then how many grams of potassium hydroxide are formed?What volume of hydrogen gas, in liters, is formed at STP ? Be sure to balance the reaction first.K (s) + H 2 O (l) KOH (aq) + H 2(g)47

4. Determine the number of moles of carbon dioxide gas, water, and sodium chloride formed by the reaction of 42.0grams of sodium bicarbonate (baking soda/NaHCO 3 ) reacting with excess hydrochloric acid. The reaction is:NaHCO 3 (s) + HCl (aq) ===> CO 2 (g) + H 2 O (l) + NaCl (aq)5. The unbalanced decomposition reaction of butane gas in excess oxygen produces carbon dioxide gas and watervapor: C 4 H 10 (l) + O 2 (g) ===> CO 2 (g) + H 2 O (l). Starting with 11.6 grams of butane, how many grams ofcarbon dioxide gas are formed at STP? What is the volume of the water vapor product?6. The burning of solid sulfur in air produces sulfur dioxide gas.S + O 2 SO 2Balance the reaction. How many moles and molecules (particles) of sulfur dioxide does the burning of 3 moles ofsulfur form? Calculate the volume of sulfur dioxide produced at STP.48

7. The Haber reaction produces ammonia, an important nitrogenous compound needed to make plant fertilizers. Theunbalanced reaction is: N 2 (g) + H 2 (g) ===> NH 3 (g) + heat. Is the reaction exothermic or endothermic ? If170.0 grams of ammonia (NH 3 ) are produced, then how many grams of nitrogen gas are needed? How manymolecules of hydrogen gas are needed?8. The unbalanced single displacement reaction between sodium metal and water is quite violent:Na (s) + H 2 O (l) ===> NaOH (aq) + H 2 (g) + heat + lightIf 44.8 liters of hydrogen gas are formed at STP, then how many grams of sodium and water are needed?9. Given the reaction: H 2 (g) + O 2 (g) ===> H 2 O (g) . How many moles of oxygen gas are needed to produce 11.2liters of water vapor at STP ? How many molecules of hydrogen gas are needed?49

10. The unbalanced synthesis reaction between aluminum metal and oxygen is:Al (s) + O 2 (g) ===> Al 2 O 3 (s).If 6.02 X 10 25 molecules of aluminum oxide are produced, then how many grams of aluminum metal and oxygengas are needed?11. The decomposition of mercury (II) oxide to produce liquid mercury and gaseous oxygen is shown in this unbalancedreaction:HgO (s) + heat ===> Hg (l) + O 2 (g)How many grams of mercury (II) oxide are needed to produce 100.3 grams of liquid mercury ? What volume ofoxygen gas is formed at STP?12. The unbalanced synthesis reaction of hydrogen gas with chlorine gas produces hydrogen chloride gas:H 2 (g) + Cl 2 (g) ===> HCl (g)How many grams of hydrogen gas are needed to produce 146.4 grams of hydrogen chloride gas? What volume ofchlorine gas, at STP, is needed?50

Name: Date: Period:Stoichiometry is the relation between the quantities of that take part in a reaction. In other words, we can usestoichiomety to figure out how much of a product we will produce knowing the amount of reactants we start with.You will be conducting a lab in which you mix sodium hydrogen carbonate, NaHCO 3 , (baking soda) and acetic acid,CH 3 COOH , (vinegar) together and then you will observe the results. You will also predict the amount of carbon dioxide,water and sodium acetate (NaCH 3 COO) produced and will calculate the percent yield based on the amount that youactually recover.Please make sure you take good notes and observations because you will be writing a formal lab report on this lab. Thefollowing is the chemical reaction that will take place:NaHCO 3 (aq) + CH 3 COOH (aq) ----> CO 2 (g) + H 2 O (l) + NaCH 3 COO (aq)Baking soda + vinegar ----> carbon dioxide + water + sodium acetatePRE-LAB QUESTIONS1.) What are the reactants?2.) What are the products?3.) Is the chemical equation balanced or not? Show your work. If it is not balanced, please balance it!4.) What do you think the purpose of completing this lab is? Write your answers in complete sentences.PERCENT YIELD QUESTIONS5.) If we mixed 25 grams of sodium bromide (NaBr) with a large amount of potassium chloride (KCl), what will ourtheoretical yield of sodium chloride (NaCl) be (meaning – how many grams of sodium chloride are we supposed to getfrom this reaction?)The reaction is:NaBr + KCl ------> NaCl + KBr51

6.) If our actual yield was 13 grams of sodium chloride, what would our percent yield for this reaction be?Formula for percent yield is:Example: I expected to get 30 grams; I ended up getting 25 grams.7.) Is the answer in #6 reasonable? If so, explain why you think this was a reasonable answer.8.) What are some factors that might cause the percent yield to be lower than 100%? Make sure you discuss specificexamples of how this might happen.IntroductionIn this lab, you will need to do a reaction where baking soda will react with an excess of vinegar. By doing this, you will(hopefully!) ensure that you will get 100% actual yield for the reaction.For our reaction, we will need to use 0.05 moles of baking soda, which we will call by its chemical name, sodiumhydrogen carbonate (NaHCO 3 ) for the rest of this lab. If we use much more than 0.05 moles of baking soda, the reactionwill be too large and we will rest having some of the reaction products pour over the side of the flask when we mix itwith the vinegar (which we call acetic acid – CH 3 COOH).In the space below, use dimensional analysis to calculate the amount of sodium hydrogen carbonate we will need forthis lab:FOR THIS LAB, WE WILL USE ______________GRAMS OF SODIUM HYDROGEN CARBONATE52

Using stoichiometry, how many moles and grams of sodium acetate do we expect to get? Show your calculations below.Using stoichiometry, how many moles and liters of CO 2 do we expect to get? Show your calculations below.Materials_____grams of baking soda (how much did you calculate you would need in the introduction?)150 mL of vinegar1 cupA 500 mL flaskStirring rod30 ml of waterHot plateGraduated cylinderMethodsIn this section, you will now carry out the reaction that was discussed at the beginning of this lab.1.) Observe 3 physical properties of vinegar and baking soda. Write down your observations in the Data & Observationsection of this lab.2.) In a cup, measure out the weight of sodium hydrogen carbonate that you calculated you would need in theintroduction section of this lab. Don’t forget to tare (zero) the weight of the cup. Make sure the amount that you use isas close as possible to the amount that you calculated. Write the exact amount of sodium hydrogen carbonate that youused here:Amount of sodium hydrogen carbonate that you actually used: _____________________grams3.) Add 30 mL of water to the cup containing the sodium hydrogen carbonate. Stir the solution until most or all of it isdissolved (if a little won’t dissolve, that’s okay).4.) Weigh a 500 mL flask. You will need the weight of an empty flask at the end of the lab.Weight of empty 500 mL flask: __________________ grams5.) Add the sodium hydrogen carbonate solution to the empty 500 mL flask.6.) In a graduated cylinder, measure out 150 mL of acetic acid (aka vinegar) and slowly add it to the sodium hydrogencarbonate solution. You will observe the formation of bubbles when the acetic acid is added to the sodium hydrogen53

carbonate solution. Wait until the bubbling subsides before adding more acetic acid. When all the acetic acid has beenadded, stir for two minutes before moving on to step 6.7.) When the solution is calm again (there may be a few bubbles rising from the bottom of the flask – this is normal),move the flask to a hot plate and heat it to boiling. Be careful that the flask does not boil over because this will causeerrors in your calculations. Put the flask in the hood.8.) When all of the liquid in the solution has boiled away, remove the flask from the hot plate. The power that youobserve inside is the product of the reaction, sodium acetate. Once the flask has had a few minutes to cool down toroom temperature, measure and record its weight.Weight of the flask, after the reaction: _______________9.) When done, rinse out the flask and any other glassware you used. All waste can go down the sink.Data and ObservationsBefore the chemical reaction1. The chemical equation of the reaction between baking soda and vinegar isNaHCO 3 (aq) + CH 3 COOH (aq) ----> CO 2 (g) + H 2 O (l) + CH 3 COONa (aq)Show your calculations for how you found out how many grams of baking soda to use in this lab.Show your calculations for how you found out how many grams of sodium acetate to expect in this lab.Show your calculations for how you found out how many liters of CO 2 to expect from this lab.2. Write down 3 physical properties of baking soda.3. Write down 3 physical properties of vinegar.54

4. What was the mass of the empty 500 mL flask? _________________After the Chemical Reaction5. Write down 3 observations about the chemical reaction after you mixed the baking soda and vinegar.6. What was the weight of the 500-mL flask after the reaction? ______________7. How many grams of sodium acetate were produced? Show your calculations for how you got your answer.8. Using the weight of sodium acetate that you got and the weight of sodium acetate that you were supposed to get,calculate the percent yield for this experiment. Show your calculations below.Results and Discussion1. Why do scientists use stoichiometry? How did it help us in this lab? What did we figure out from using it?2. Did a chemical reaction take place? How do you know? What evidence tells you whether a chemical reactionhappened or not?3. Was your percent yield for sodium acetate 100%? Why or why not?4. Do you think it is common for scientists to get a 100% percent yields for chemical reactions? Why or why not?55

5. If you had to do this lab again, what would you do differently? Explain using specific examples.6. You measured how many grams you actually got for sodium acetate at the end of the chemical reaction. Using yourknowledge of moles and particles, figure out how many molecules (particles) of sodium acetate you actually ended upwith. Show your calculations below.56

Name: Date: Period:An essential part of conducting experiments in chemistry is reporting your results and findings in a formal lab report.You will be writing a lab report to convey everything you did and learned from the chemical reaction of baking soda andvinegar.Use the following outline:Title PageYou must have a title page that includes…ooooThe title of the experiment (please do NOT call it stoichiometry lab report, be more specific about whatchemical reaction/experiment we conducted). Please refer to the “title” section below.Your name and the names of any lab partners.Your instructor's name.The date the report is due.IntroductionThings to include in your introduction:What chemical reaction did we perform in this lab? What are the reactants and products?What was the purpose of doing this lab? What is the purpose of stoichiometry?Summarize how we did the baking soda and vinegar lab.Summarize how you found out how much baking soda to start off with.Summarize how you found out how much sodium acetate you are expected to get.MaterialsList everything needed to complete your experiment. Be as specific as possible.Ex: 20 grams of baking soda (not just baking soda)MethodsDescribe the steps you completed during your investigation. This is your procedure. Be sufficiently detailed that anyonecould read this section and duplicate your experiment. Write it as if you were giving direction for someone else to do thelab. Write your method in paragraph form. You may use the instructions I gave you, but do NOT copy it word for word.You also need to write your methods section in third person (so do NOT use words like “I,” “me,” or “you.”Data & ObservationNumerical data obtained from your procedure usually is presented as a table. Data encompasses what you recordedwhen you conducted the experiment. It's just the facts, not any interpretation of what they mean. You also will includeany calculations that you may have done.Type up all the questions in the data and observations sectionResults & DiscussionDescribe in words what the data means.Type up all the questions in the results and discussion section57