Chemical Quantities Homework. cincochem.pbworks.com. Name Academic Chemistry

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1 Unit 6 Periodic Table Name Academic Chemistry Chemical Quantities Homework DATE ASSIGNMENT On-Time LATE Somewhere, something incredible is waiting to be known. Carl Sagan 20 cincochem.pbworks.com Chemical Quantities cincochem.pbworks.com

2 WARMUP Unit 6 Day 1 Resources Common Polyatomic Ions List Day 2 Day 3 20 Name Common Polyatomic Ions Name Ion acetate C 2 H 3 O 2 or CH3 COO hypochlorite ClO ammonium + NH 4 nitrate NO 3 carbonate 2 CO 3 nitrite NO 2 chlorate ClO 3 perchlorate ClO 4 chlorite ClO 2 permanganate MnO 4 chromate 2 CrO 4 phosphate 3 PO 4 cyanide CN phosphite 3 PO 3 dichromate 2 Cr 2 O 7 silicate 2 SiO 3 hydrogen carbonate HCO 3 sulfate 2 SO 4 hydroxide OH sulfite 2 SO 3 How to key scientific notation into a TI calculator: Day 4 Type in 6.02 x : Should display: How to key molar mass into a TI calculator in ONE STEP!: Day 5 Example: Na 2 SO 4 Mole conversion chart Day 6 Mass Grams Molar Mass MOLES Representative Particles Atoms, Molecules, Formula Units Roman Numerals for Transition Metals = I 2 = II 3 = III 4 = IV 5 = V 6 = VI 2 cincochem.pbworks.com Chemical Quantities Chemical Quantities cincochem.pbworks.com 19

3 Warmups Day 7 Molar Mass Homework 6.1 Find the molar mass of the compound. Round average atomic mass to the hundredths place. Show units. Day 8 1. NaCl 2. Ca(OH) 2 Na = Ca = Cl = O = NaCl = H = Ca(OH) 2 = Day 9 3. Fe 2 O 3 4. Ammonium phosphate Day Al 2 (SO 4 ) 3 6. Dinitrogen trioxide Day 11 Day An alien visits earth. He brings with him an unknown substance. He says, I believe this substance is like an Earthly compound; it is either like nitrogen dioxide or nitrogen trioxide. I m not sure which. All I know is that its molar mass is g. Which compound did the alien bring with him? Show your work to receive credit. 18 cincochem.pbworks.com Chemical Quantities Chemical Quantities cincochem.pbworks.com 3

4 Homework 6.2 Conversions - Mass Complete the following conversions using dimensional analysis. Show work! 1. Convert mol of calcium cyanide, Ca(CN) 2, to mass. Mixed Questions Extra Practice 3. Many teenage females are anemic (they don t have enough iron in their blood). The FDA recommends that teenage girls consume at least x atoms of iron daily. How many grams is this? 2. How many grams are in 0.50 mol of copper (II) sulfate? One steak contains grams of iron. If Sasha eats one steak per day (and no other iron), will she get enough iron? 4. Find the molar mass of calcium sulfite. 3. Convert 30 g of silicon dihydride to moles. 5. What is the mass of 1.94 mol of dinitrogen pentoxide? 6. How many moles are in 205 g of carbon tetrachloride? 4. How many moles are in 100 grams of potassium sulfide? 7. How many moles are in 7.21 x formula units of barium chloride 4 cincochem.pbworks.com Chemical Quantities Chemical Quantities cincochem.pbworks.com 17

5 Extra Practice Mixed Questions Conversions - Mass Homework Your mom asks you to put away the leftovers after dinner. You ask her, What should I use? She replies, Use 3.5 moles of aluminum foil, of course! How many atoms of aluminum foil should you use? 5. Your grandfather has to take 5 grams of aspirin (C 8 H 8 O 4 ) daily for his arthritis. How many moles of aspirin should he take? 6. You go to the pawn shop to buy your girlfriend some jewelry. The clerk offers to sell you a necklace that has 5 grams of gold in it for $300. How many moles of gold are in the necklace? 2. Nicki Minaj plans to throw the wildest New Year s Eve concert ever, and in doing so plans to have a huge bubbling cauldron, so she asks you, her manager, to make it happen. To maintain bubbling for the entirety of her 38 minute concert you will need moles of dry ice, or frozen carbon dioxide. How many grams of dry ice do you need? 7. You are conducting a lab experiment to evaluate the reaction between calcium hydroxide and hydrochloric acid. Your teacher has told you how much of each reactant to use (in moles). You must convert to mass before you can start. Complete the table. Packages of dry ice come in increments of 500 grams. How many packages do you need to purchase? Name of Compound calcium hydroxide hydrochloric acid Formula of Compound Molar Mass Moles Needed Mass Needed 2.0 mol 4.0 mol 16 cincochem.pbworks.com Chemical Quantities Chemical Quantities cincochem.pbworks.com 5

6 Homework 6.3 Conversions - Particles Complete the following conversions using dimensional analysis. Show work! 1. How many moles are in 1.50 x molecules of nitrogen trihydride? Molecular Formula Homework Elaidic acid is the primary trans fatty acid present in partially hydrogenated oils used in food production. Calculate the molecular formula for elaidic acid given that it has an empirical formula of C 9 H 17 O 1 and a mass of 282 g/mol. 2. Convert 4.8 moles of calcium carbonate to formula units. 3. How many molecules are in 4.80 x 10 3 mol bromine gas? 4. Strychnine, a deadly poison, has a mass of 334 amu and a percentage composition of 75.42% carbon, 6.63% hydrogen, 8.38% nitrogen, and 9.57% oxygen. What is the molecular formula of strychnine? 4. There are moles in 3.73 x formula units of barium chloride. 6 cincochem.pbworks.com Chemical Quantities Chemical Quantities cincochem.pbworks.com 15

7 Homework 6.7 Molecular Formula Conversions - Particles Homework 6.3 Answer the following questions concerning molecular formulae. Use the steps outlined in your notes. 1. Find the molecular formula for a compound with a molar mass of g/mol and an empirical formula of CHO 2. Step 1: 5. Your doctor prescribes you lithium carbonate for your bipolar disorder. Examine the prescription below. Dr. Emilio Avogadro Date Oct 23, 2012 Patient: Kim Estudiante : Take 5 mol Lithium Carbonate Once daily at bedtime Signature E. Avogadro How many formula units of lithium carbonate will you ingest each day? Step 2: Step 3: 6. The same pawn shop clerk from HW 6.2 says, Okay, you don t like that necklace? How about these earrings? They have 1.00 x atoms of gold in them! How many moles of gold is this? 2. Find the molecular formula for a compound with 46.68% nitrogen and 53.32% oxygen and a molar mass of g/mol. 7. A cold pack uses an endothermic reaction to cool its surroundings. Inside a cold pack are 5.33 x formula units of ammonium nitrate. How many moles of ammonium nitrate are in a cold pack? 14 cincochem.pbworks.com Chemical Quantities Chemical Quantities cincochem.pbworks.com 7

8 Homework 6.4 Conversions - Mixed Complete the following conversions using dimensional analysis. Show work! 1. Convert 3.33 x atoms of sodium to grams. Empirical Formula Homework Sodium sulfite is a meat preservative and sodium sulfate is a laxative. Your grandmother gives you a side of beef for your birthday and you d like to keep it from rotting. You ve found a sample of a compound of sodium that contains 36.5 grams of sodium, 25.4 grams of sulfur, and 38.1 grams of oxygen. Do you have a laxative or the meat preservative you so desperately need? 2. There are moles in 187 g aluminum. 3. How many grams are in 40 moles of ammonium chloride? 4. As lead arson investigator with the Houston Fire Department you find a small sample of the accelerant (fuel) that caused a fire that took the lives of 11 people in an urban apartment complex. You run the sample through a mass spectrometer and find that it contains 37.5% carbon, 12.5% hydrogen, and 50.0% oxygen, by mass. Determine the empirical formula of this substance. 4. How many moles are in 333 g tin (II) fluoride? 8 cincochem.pbworks.com Chemical Quantities Chemical Quantities cincochem.pbworks.com 13

9 Homework 6.6 Empirical Formula Conversions Mixed Homework 6.4 Answer the following questions concerning empirical formulae. Use the steps outlined in your notes. 5. Convert 5.00 x molecules hydrogen (H 2 ) to grams. 1. Determine the empirical formula for a compound containing grams potassium and 4.00 grams oxygen. Step 1 Step 2 Step 3 6. In 1970, Nobel Prize winning scientist Linus Pauling recommended taking megadoses of vitamin C to ward off the common cold. He suggested taking up to 2.5 grams per day. How many molecules of vitamin C (C 6 H 8 O 6 ) did he recommend that you should take per day? 2. A compound contains grams of iron and grams of oxygen. Construct the empirical formula. 7. Have you ever tried the energy drink Crunk!!!? It smade by Lil Jon (the rapper) and it is so yummy! It even has 62 grams of amazing sugar (C 12 H 22 O 11 ) per can! That s like molecules of sugar! 12 cincochem.pbworks.com Chemical Quantities Chemical Quantities cincochem.pbworks.com 9

10 Homework 6.5 Percent Composition Percent Composition Homework Write the formula for percent composition below. Use the formula and the information given in subsequent questions to complete this assignment. % composition = x 100% 4. A sample of liquid with a mass of grams was decomposed into its elements and gave grams of carbon, grams of hydrogen, and grams of oxygen. What is the percent composition of this oxygen in this compound? (hint: you don t need to calculate molar mass to solve this problem, just use the formula from question #1) 2. Find the percent composition of hydrogen in each compound: a) Ca(OH) 2 % of H = b) C 2 H 6 % of H = c) Al (C 2 H 3 O 2 ) 3 % of H = 5. A quantitative analysis of grams of an unknown solid found grams of carbon, grams of hydrogen and grams of oxygen. Calculate the percent composition of carbon in this compound. (hint: you don t need to calculate molar mass to solve this problem, just use the formula from question #1) 3. Find the percent composition of each element in these compounds: a) NaCl molar mass = % of Na = 6. What is the percentage of Fe in FeCO3? % of Cl = b) (NH 4 ) 2 S molar mass = % of N = % of H = % of S = 10 cincochem.pbworks.com Chemical Quantities Chemical Quantities cincochem.pbworks.com 11