Unit 6 Assignment Packet Name Period A1 Worksheet: Writing and Balancing Chemical Equations 1. Describe the following word equation with a statement or sentence: Iron + Oxygen iron (III) oxide 2. In a chemical equation, what is the purpose of the arrow? 3. How are the symbols (s), (l), (g) and (aq) used in an equation? 4. What is a catalyst and where is it shown in a chemical equation? 5. Describe a Combination Reaction: 6. Describe a Decomposition Reaction: 7. Describe a Single Replacement Reaction: 8. Describe a Double Replacement Reaction: 9. Describe a Combustion Reaction: 10. When a hydrocarbon is a reactant in a combustion reaction, and are the products. 11. An element like magnesium can also react with oxygen. Give an example of a combustion reaction involving an element as one of the reactants. 1
12. Match the generic equations given with their reaction type: a. RS R + S b. R+S- + T+U- R+U- + T+S- c. CxHy +?O 2?CO 2 +?H 2 O d. R + S RS e. T + RS TS + R 13. Write the Law of Conservation of Mass 14. Balance the following equations: Classify reaction type: KNO 3 KNO 2 + O 2 Al + HCl AlCl 3 + H 2 CO + O 2 CO 2 C 4 H 10 + O 2 CO 2 + H 2 O Th(NO 3 ) 4 + K 3 PO 4 Th 3 (PO 4 ) 4 + KNO 3 A2 Worksheet: Writing and Balancing Chemical Equations 15. Balance the following equations: Classify reaction type: H 2 O 2 H 2 O + O 2 Pb(NO 3 ) 2 + NaCl PbCl 2 + NaNO 3 CH 4 + O 2 CO 2 + H 2 O PBr 3 + H 2 O H 3 PO 3 + HBr Na + H 2 O NaOH + H 2 16. Complete each of the following descriptions by writing the balanced chemical equation with chemical formulas and symbols. Refer to the text for help with symbols and formulas. When metallic iron is dropped into a solution of hydrochloric acid, bubbles of hydrogen gas and an iron (II) chloride solution are produced. Lithium metal burns in the presence of oxygen gas to generate solid lithium oxide. Solid calcium carbonate reacts with sulfuric acid (H 2 SO 4 ) to form solid calcium sulfate, carbon dioxide, and water 2
Solid copper (II) chloride will react with a phosphoric acid (H 3 PO 4 ) solution to form copper (II) phosphate and hydrogen chloride, both in solution. Hydrogen peroxide solution will react in the presence of a manganese dioxide catalyst to generate water and oxygen gas. 17. In each of the following reactions, describe the observable evidence that indicates a chemical reaction has occurred. Balance each equation. Also identify each reaction type. Reaction Type C 3 H 8(g) + O 2(g) CO 2(g) + H 2 O (g) + energy Observable Evidence= NaHCO 3(s) + HCl (aq) H 2 O (l) + CO 2(g) + NaCl (aq) Observable Evidence= Pb(NO 3 ) 2(aq) + KI (aq) PbI 2(s) + KNO 3(aq) Observable Evidence= Cu (s) + AgNO 3(aq) Ag (s) + Cu(NO 3 ) 2(aq) Observable Evidence= A3 Worksheet: Balanced Equations and Mole Relationships 1. For each of the following reactions, Balance the equations, then solve the problems: a. How many moles of KClO 3 are needed to produce 0.366 moles of O 2? KClO 3 KCl + O 2 b. How many moles of H 2 O are produced from 9.45 moles of NH 4 NO 3? NH 4 NO 3 N 2 O + H 2 O 3
2. Aluminum sulfate, Al 2 (SO 4 ) 3 is used in fireproofing fabrics and the manufacture of antiperspirants. Al 2 O 3(s) + H 2 SO 4(aq) Al 2 (SO 4 ) 3(aq) + H 2 O (l) a. How many moles of Al 2 (SO 4 ) 3 would be produced if 6 mol of H 2 SO 4 reacted with excess Al 2 O 3? b. How many moles of Al 2 O 3 are required to make 2 mol of H 2 O? 3. Copper (II) nitrate, Cu(NO 3 ) 2, is used to give a dark finish to items made o f copper metal, making them appear antique. Balance the equation below, then complete the following table: Cu(s) + HNO 3 (aq) Cu(NO 3 ) 2 (aq) + H 2 O(l) + NO(g) Equation Cu HNO 3 Cu(NO 3 ) 2 H 2 O NO # of moles Molar Mass Total Mass State of Matter What is the total mass of the reactants? What is the total mass of the products? What law does the comparison of the mass of the reactants and products follow? A4 Worksheet : Stoichiometry Make sure each equation is BALANCED before working on the Stoichiometry problem! 1. Baking Powder consists of a mixture of Baking Soda (sodium bicarbonate, NaHCO3) and some solid acid so that the moistened mixture will react to form CO 2 gas. When sodium dihydrogen phosphate, NaH 2 PO 4, is used in this reaction, the following reaction occurs, NaHCO 3 + NaH 2 PO 4 Na 2 HPO 4 + H 2 O + CO 2 What mass of sodium dihydrogen phosphate (NaH 2 PO 4 ) must be used to completely react with 0.65 mole of baking soda. 4
2. Calcium cyanide powder is used by beekeepers to destroy a colony of diseased bees. This powder must be stored in a closed container, since moist air decomposes it, according to the equation: Ca(CN) 2 + H 2 O Ca(OH) 2 + HCN Determine the number of moles of water needed to liberate 94.5g of HCN gas. 3. Stannous flouride is a common toothpaste additive as a source of flourideion for retarding tooth decay. It may be manufactured from tin and dry hydrogen flouride gas: Sn + HF SnF 2 + H 2 If 31.4g of SnF 2 are to be produced what mass of hydrogen gas will be liberated? 4. Fools gold is pyrite ore, and it contains beautiful crystals of FeS 2. This is also a source of iron metal, and so is somewhat valuable although it isn t gold. How many grams of this ore must be used to obtain 255 kg of pure iron? FeS 2 Fe + S 8 5. How many moles of oxygen are required to produce 242 grams of MgO, magnesium oxide? Mg + O 2 MgO 6. Welders use the reaction of Acetylene (C 2 H 2 ) and Oxygen (O 2 ) to provide energy for their welds. The equation for the reaction is: C 2 H 2 + O 2 CO 2 + H 2 O What volume of Oxygen (O 2 ) will be required to burn 52 grams of Acetylene (C 2 H 2 )? A5 Worksheet : Stoichiometry 7. Silicon Carbide is one of the hardest substances known to man. It is used extensively in sharpening stones and other tools. Silicon Carbide (SiC) is made by the following reaction. SiO 2 + C SiC + CO What mass of carbon C is required to produce 5.0 grams of Silicon Carbide? 5
8. The odorous compound Dimethyl Mercapitan (C 2 H 6 S) is burned to Sulfur Dioxide (SO 2 ). C 2 H 6 S + O 2 CO 2 + H 2 O + SO 2 What volume of Sulfur Dioxide (SO 2 ) is produced by each 1.000 kg of Dimethyl Mercapitan (C 2 H 6 S) burned? 9. An astronaut on the moon missions consumes 1.000 kg units of carbohydrates (C 6 H 12 O 6 ) per day. These react in his body as follows: C 6 H 12 O 6 + O 2 CO 2 + H 2 O How many grams of Oxygen are required to sustain the astronaut each day? Use the following equation to solve the next three stoichiometry problems (10-12): Li 3 N + H 2 O NH 3 + LiOH 10. What mass of water is needed to react with 7.30 x 10 24 formula units of Li 3 N? 11. When 13.3 ml of NH 3 are produced how many formula units of LiOH are also produced? 12. When 4.0 x 10 12 molecules of water are used, how many grams of NH 3 are produced? A6: Worksheet: Limiting Reagent Percent Yield 1. What is a Limiting Reagent? 2. What is an Excess Reagent? 3. When solving for an amount of a product formed by stoichiometry, which reagent should be used? 4. What is Actual Yield? 5. What is Theoretical Yield? 6
6. What is Percent Yield? Identify and use the limiting reagent in a reaction to calculate the maximum amount of product(s) produced and the amount of excess reagent. 7. Aluminum (Al) reacts with bromine (Br 2 ) in a combination reaction to form Aluminum bromide (AlBr 3 ). a. Write the balanced equation for this reaction. b. Identify the limiting reagent and calculate how many grams of product can be made from 2.2 x 10 24 atoms of aluminum reacting with 500 grams of bromine? 8. C 3 H 7 O completely combusts. (remember: H 2 O and CO 2?) a. Write the balanced equation for this reaction. b. If 87 Liters of oxygen reacts with 87 grams of C 3 H 7 O find the limiting reagent. Then calculate the volume of carbon dioxide that can be produced (assume STP)? c. How many moles of excess reagent are left over, unused? Calculate the theoretical yield, actual yield, or percent yield given appropriate information. 9. Silicon dioxide reacts with carbon to produce silicon carbide (SiC) and carbon monoxide. a. Write the balanced equation for this reaction. b. If 75 grams of silicon dioxide is heated with excess of carbon, 31.9 grams of silicon carbide is produced. What is the percent yield of this reaction? 7
10. A solution of rubidium carbonate reacts with aqueous magnesium sulfate in a double replacement reaction. Magnesium carbonate is not soluble. a. Write the balanced equation for this reaction. b. If the reaction proceeds with an 87% yield, how many grams of precipitate are collected when 12 grams of magnesium sulfate reacts with excess rubidium carbonate? c. How many formula units of rubidium carbonate are consumed when the reaction from part b. proceeds? Calculate the % yield from experimental data after identifying the limiting reagent. 11. Write the complete balanced equation for the single replacement reaction between a solution of copper (II) sulfate, CuSO 4 and the element aluminum, Al. You dissolve 25.0 grams of copper (II) sulfate, then react it with 5.0 grams of aluminum. Upon collecting the copper produced, you dry it and determine the collected copper s mass to be 9.0 grams. a. Show your work, and also explain how you know which reactant was the limiting reagent and which was in excess. b. Show your work for calculating the % yield of this experiment. c. How many grams of copper (II) sulfate went unreacted? 8