Chemistry Themed Materials Sections D.1-D.6

Transcription

1 Chemistry Themed Materials Sections D.1-D.6 Balancing Chemical Equations

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3 Chemistry Themed Materials Sections D.1-D.6 Date In-Class Assignment Homework F 10/2 Go over Quiz; questions on HW (notes pkt p. 7) Demo: Copper and Nitric Acid (atom inventory) pkt p 9-11 M 10/5 Discuss Copper and Nitric Acid pages if needed Discuss D.2 Modeling Matter Balancing Equations pkt p Balancing Equations pkt p 17 Finish Copper and Nitric Acid pages Complete D.2 Modeling Matter #1-3 textbook p pkt p 12 Read/Notes D.3 textbook p pkt p 12 Complete Developing Skills D.4 textbook p #1-4, 6 pkt p 13 Finish pkt p17 Complete pkt p 23 (Word Equations) #1-2 T 10/6 Go over pkt p 17 Go over pkt p 23 #1-2 Finish pkt p 23 Work on pkt p Study for Balancing Quiz! Look at Sections D.1-D.6 textbook p for review W 10/7 Late Start Day QUIZ ON BALANCING CHEMICAL REACTIONS! 3

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5 Chemistry Name: Period: Materials Unit: Sec. D.1 D.6 Objectives Checklist My action plan to help me improve my learning includes: Review labs, notes, packet and activities. Use the calendar to make sure everything is reviewed. Have a family member or friend quiz me orally. Meet with my teacher in the morning/afterschool for extra help. Use the magic calculator online to check your calculation answers to appropriate labs. Complete and review homework problems by reworking them and NOT just looking at them. Use Objective Checklist throughout unit to assess understanding Ask and answer questions during class. Start studying early! (Not just the night before the test.) Re-read or review all assigned sections from the book. Do online practice quizzes available through class website or through internet. Find a study buddy from Chemistry who understands the material and I can work well with. Use Objective Checklist as a study guide Use this checklist as your personal guide to assess your level of readiness for quizzes and the unit test. Circle the descriptor that best describes how you feel about your mastery of each objective. NOTE: IF IT IS NOT A, YOU PROBABLY ARE NOT READY FOR THE QUIZ/TEST!!!!! = I get it? = I need more practice/review! = I need to get help During Unit Before Test (An asterisk indicates an overarching theme from a past unit!) I feel confident that I?!?! 9. understand the Law of Conservation of matter and its implication for our natural resources.?!?! 10. can balance chemical equations given chemical formulas.?!?! 11. can balance chemical equations given chemical names. Check off the study skills you USED to move from? or! to while studying for the test. I have carefully self-assessed my work during this unit and have taken steps to get my questions answered before the quiz/test. Student Signature: Parent Signature: Date: 5

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7 Notes for Section D.1 Take notes below for Section D.1, p in the textbook: Law of Conservation of Matter Demo Write your notes below for the Pb(NO3)2 and KI demo that is done in class: 7

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9 Using Up A Metal A Demonstration PURPOSE: The purpose of this demo is to observe the chemical reaction between nitric acid (HNO3) and copper metal (Cu) and to explain the observed changes using the Law of Conservation of Matter. BACKGROUND INFORMATION: What is the Law of Conservation of Matter? This is the chemical reaction that is taking place. Cu (s) + 4 HNO3 (aq) Cu(NO3)2 (aq) + 2 NO2 (aq) + 2 H2O (l) NOTE: When an ionic substance or acid is aqueous (dissolved in water), it exists in solution as separate ions, NOT as a molecule or formula unit. For example, aqueous nitric acid consists of hydrogen ions (H + ) and nitrate ions (NO3 - ), not as HNO3 "molecules." Substances that exist as a solid, liquid or gas exist as molecules/atoms. PROCEDURE: 1. Your teacher will show you a sample of copper. -RECORD observations of copper in data table. 2. Your teacher will show you a bottle of nitric acid. -RECORD observations of nitric acid in data table. 3. Your teacher will CAREFULLY add just enough nitric acid to the well to cover the copper wire. 4. Observe the reaction for 5 minutes. RECORD all changes observed. Data Table: REACTANTS Record initial observations: Copper: PRODUCTS Record ALL observations: Nitric Acid: 9

10 QUESTIONS: 1. In the space below, rewrite the chemical equation for this reaction and perform an atom inventory. 2. Is this equation balanced? 3. Interpret the chemical equation using words (HINT: NO2 is nitrogen dioxide). 4. Rewrite the chemical equation representing each substance at the particle level eg if it exists as a molecule, represent it as a molecule; if it exists as an ion, represent it as an ion. Keep polyatomic ions (eg nitrate) as a single unit. Use the example.as a guide. HINT: look back at the background information for help in determining if a substance exists as a molecule or an ion. EX: 2 H2 (g) + O2 (g) 2 H2O (g) 10

11 5. Using your answer from #4 and your data, answer the following questions: a. You observed several color changes during the reaction. Identify the color of each substance in the product side of the equation. b. Where did the copper atoms from the initial piece of copper "go"? c. What elements were in the gas molecules released by the reaction? d. Where did these atoms come from? e. Where did the atoms in the water produced come from? EXTENSION QUESTION: 6. You are probably familiar with the reaction between vinegar and baking soda. Vinegar has the chemical name of acetic acid and baking soda has the chemical name of sodium bicarbonate. Here is the reaction: HC2H3O2 (aq) + NaHCO3 (s) NaC2H3O2 + H2O (l) + CO2 (g) a. Where did the acetate ions (C2H3O2 - ) from the acetic acid go? b. Where did each of the atoms that make up the water come from? 11

12 Section D.2: Modeling Matter Complete Section D.2 textbook p , Modeling Matter #1-3 below: Notes for Section D.3 Write your notes from Section D.3 textbook p : 12

13 Complete Section D.4 textbook p #1-4, 6: Section D.4: Developing Skills 13

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15 Balancing Equations Rules Balancing chemical equations is essential to chemistry. As the law of conservation of matter states, atoms cannot be created or destroyed. Use the following rules to help you with this concept. Rule #1 Always perform an atom inventory (count up the atoms!) Example: H2 + O2 H2O The subscripts are telling you how many of the atoms are in the molecule. In the example H2 tells you that there are 2 hydrogen atoms bonded together. What does O2 mean? If you said 2 atoms of oxygen are bonded together some people would say that you are a chemistry genius and you should be moved to AP Chem, other people would just tell you that you are correct. Finally, this reaction yields H2O. In a molecule of water we have 2 atoms of hydrogen bonded with 1 atom of oxygen. The question that arises is if the equation is balanced? If you said no, you once again are a chemistry genius, if you said yes it is, then you are just a donkey-donk! So how do we balance it? Try counting the atoms. We have 2 atoms of hydrogen on the left and also 2 atoms of oxygen on the left of the equation. On the right of the arrow we have 2 atoms of hydrogen and 1 atom of oxygen. So what is unbalanced? The oxygen! Now in order to balance the equation you change the coefficient, NEVER EVER EVER EVER EVER EVER change the subscripts!! REMEMBER THAT! If you forgot what a coefficient is, it's that big number that comes in front of a molecule in a chemical equation. Look below to find the balanced equation: 2 H2 + O2 2 H2O Recount the atoms. You now have 2 molecules of H2, so to calculate the number of atoms you take the coefficient times the subscript (2 * 2), to get 4 hydrogen atoms. You still have 2 oxygen atoms on the left of the equation. On the right you now have 2 water molecules, each of which has 2 atoms of hydrogen, so once again 2 * 2 gives you 4 total hydrogen atoms. Next, look at the oxygen in water. You have two water molecules, each of which have only 1 oxygen, so (1 * 2) there is a total of 2 oxygen atoms. Low and behold, the equation is now balanced!!!! BOOM! 15

16 Rule #2 Pick an atom that appears only once on each side of the equation. Leave the hydrogen and oxygen atoms until the end to balance. Example: C2H6 + O2 CO2 + H2O In this problem you would balance the carbon atoms first because they appear only once on each side of the equation. Next, balance the hydrogen atoms, then the oxygen atoms. Final balanced equation: 2 C2H6 + 7 O2 4 CO2 + 6 H2O Rule #3 Inventory polyatomic ions as a unit of their own. This is because they never change on either side of the equation. So if you have two of a polyatomic ion on one side of the equation you will need two on the right side of the equation. You will change the number of polyatomic ions by changing the coefficients of course! Example: Fe2O3 + H2SO4 Fe2(SO4)3 + H2O (notice that sulfate is the polyatomic ion, one of them are on the left of the equation and three sulfates are on the right of the equation) Example Balanced: Fe2O3 + 3 H2SO4 Fe2(SO4)3 + 3 H2O Notice how there are 3 sulfate polyatomic ions on the left and on the right. All we had to do was put a coefficient in front of H2SO4 and of course balance the hydrogen atoms. (Notice by balancing the hydrogen atoms, we also balanced the oxygen atoms). Rule #4 All coefficients MUST be whole numbers and in their lowest common factor. You can never have half of a molecule of something! Think about it, can you have half a molecule of water? The answer of course is NO! 16

17 Balancing Chemical Equations Balance the equations below: 1) N2 + H2 NH3 2) KClO3 KCl + O2 3) NaCl + F2 NaF + Cl2 4) H2 + O2 H2O 5) Pb(OH)2 + HCl H2O + PbCl2 6) AlBr3 + K2SO4 KBr + Al2(SO4)3 7) CH4 + O2 CO2 + H2O 8) C3H8 + O2 CO2 + H2O 9) C8H18 + O2 CO2 + H2O 10) FeCl3 + NaOH Fe(OH)3 + NaCl 11) P + O2 P2O5 12) Na + H2O NaOH + H2 13) Ag2O Ag + O2 14) S8 + O2 SO3 15) CO2 + H2O C6H12O6 + O2 16) K + MgBr KBr + Mg 17) HCl + CaCO3 CaCl2 + H2O + CO2 18) HNO3 + NaHCO3 NaNO3 + H2O + CO2 19) H2O + O2 H2O2 20) NaBr + CaF2 NaF + CaBr2 21) H2SO4 + NaNO2 HNO2 + Na2SO4 17

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19 Balancing Equations Worksheet Balance the equations below: 1) Na3PO4 + KOH NaOH + K3PO4 2) MgF2 + Li2CO3 MgCO3 + LiF 3) P4 + O2 P2O3 4) RbNO3 + BeF2 Be(NO3)2 + RbF 5) AgNO3 + Cu Cu(NO3)2 + Ag 6) CF4 + Br2 CBr4 + F2 7) HCN + CuSO4 H2SO4 + Cu(CN)2 8) GaF3 + Cs CsF + Ga 9) BaS + PtF2 BaF2 + PtS 10) N2 + H2 NH3 11) NaF + Br2 NaBr + F2 12) Pb(OH)2 + HCl H2O + PbCl2 13) AlBr3 + K2SO4 KBr + Al2(SO4)3 14) C3H8 + O2 CO2 + H2O 15) Na3PO4 + CaCl2 NaCl + Ca3(PO4)2 16) K + Cl2 KCl 17) Al + HCl H2 + AlCl3 18) N2 + F2 NF3 19) SO2 + Li2Se SSe2 + Li2O 20) NH3+ H2SO4 (NH4)2SO4 19

20 Balancing Equations Worksheet - Answers Note to students: You may leave blank spaces when balancing equations these will be interpreted as 1. 20

21 Balancing Equations Race Balance the equations below: 1) C3H8 + O2 CO2 + H2O 2) Al + Fe3N2 AlN + Fe 3) Na + Cl2 NaCl 4) H2O2 H2O + O2 5) C6H12O6 + O2 H2O + CO2 6) H2O + CO2 C7H8 + O2 7) NaClO3 NaCl + O2 8) (NH4)3PO4 + Pb(NO3)4 Pb3(PO4)4 + NH4NO3 9) BF3 + Li2SO3 B2(SO3)3 + LiF 10) C7H17 + O2 CO2 + H2O 11) CaCO3 + H3PO4 Ca3(PO4)2 + H2CO3 12) Ag2S Ag + S8 13) KBr + Fe(OH)3 KOH + FeBr3 14) KNO3 + H2CO3 K2CO3 + HNO3 15) Pb(OH)4 + Cu2O PbO2 + CuOH 16) Cr(NO2)2 + (NH4)2SO4 CrSO4 + NH4NO2 17) KOH + Co3(PO4)2 K3PO4 + Co(OH)2 18) Sn(NO2)4 + Pt3N4 Sn3N4 + Pt(NO2)4 19) B2Br6 + HNO3 B(NO3)3 + HBr 20) ZnS + AlP Zn3P2 + Al2S3 21

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23 Word Equations Write the word equations below as chemical equations and balance: 1) Zinc and lead (II) nitrate react to form zinc nitrate and lead. 2) Aluminum bromide and chlorine gas react to form aluminum chloride and bromine gas. 3) Sodium phosphate and calcium chloride react to form calcium phosphate and sodium chloride. 4) Potassium metal and chlorine gas combine to form potassium chloride. 5) Aluminum and hydrochloric acid (HCl) react to form aluminum chloride and hydrogen gas. 6) Calcium hydroxide and phosphoric acid (H3PO4) react to form calcium phosphate and water. 7) Copper and sulfuric acid (H2SO4) react to form copper (II) sulfate, water and sulfur dioxide. 8) Hydrogen gas and nitrogen monoxide (NO) react to form water and nitrogen gas. (Yes, the chemical formula for nitrogen monoxide is NO) 23

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