CHEM1010-Fall_04-22.ppt

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CHEM1010-Fall_04-22.ppt

  1. 1. Department of Chemistry CHEM1010 General Chemistry *********************************************** Instructor: Dr. Hong Zhang Foster Hall, Room 221 Tel: 931-6325 Email: hzhang@tntech.edu
  2. 2. CHEM1010/General Chemistry _________________________________________ Chapter 6. (L22)-Chemical Accounting <ul><li>Today’s Outline </li></ul><ul><li>..Review of Avogadro’s number, formula mass, mole, molar mass, and molar volume </li></ul><ul><li>..Introduction to mole and mass relationships in chemical reaction equations </li></ul><ul><li>..Molar relationships in chemical equations </li></ul><ul><li>..Mass relationships in chemical equations </li></ul>
  3. 3. Chapter 6. (L22)-Chemical Accounting <ul><li>Building Your </li></ul><ul><li>Chemical Vocabulary </li></ul><ul><li>NO 3 - : nitrate, an anion </li></ul><ul><li>SO 4 2- : sulfate, an anion </li></ul><ul><li>Both anions are the major anionic components of acid rain (acid precipitation, including acid rain, acid snow, acid fog, etc.) </li></ul>
  4. 4. Chapter 6. (L22)-Chemical Accounting <ul><li>One of the most important numbers in chemistry: Avogadro’s number </li></ul><ul><li>Avogadro’s number: </li></ul><ul><li>The number of atoms in a 12-g sample of carbon-12 is called Avogadro’s number </li></ul><ul><li>Avogadro’s number has been experimentally determined to be 6.0221367 ×10 23 </li></ul><ul><li>But, 6.02 ×10 23 is sufficiently enough for our purpose in general chemistry </li></ul>
  5. 5. Chapter 6. (L22)-Chemical Accounting <ul><li>Counting molecules, the unit of mole (like dozen in chemistry) </li></ul><ul><li>Definition: 1 mole is an amount of substance that contains the same number of elementary units (molecules, or atoms, or ions) as there are atoms in exactly 12 g of carbon-12. </li></ul><ul><li>By the definition of Avogadro’s number, we know that </li></ul><ul><li>1 mole is the amount of substance that contains the same number of elementary units (molecules, or atoms, or ions) exactly as the Avogadro’s number, that is, 6.02 ×10 23 . </li></ul>
  6. 6. Chapter 6. (L22)-Chemical Accounting <ul><li>Formula masses </li></ul><ul><li>Definition: Formula mass of a molecule or ion is the sum of the masses of each of the atoms represented by the formula </li></ul><ul><li>Example: </li></ul><ul><li>Formula mass of O 2 = 16.0u ×2 = 32.0u </li></ul><ul><li>Formula mass of SO 2 = 32.1u + 16.0u×2 = 64.1u </li></ul><ul><li>Formula mass of CO 2 = 12.0u + 16.0u×2 = 44.0u </li></ul>
  7. 7. Chapter 6. (L22)-Chemical Accounting <ul><li>Molar mass </li></ul><ul><li>Definition: The molar mass of a substance is the mass of 1 mole of that substance in the unit of gram. It is numerically equivalent to the atomic mass of the atom or the formula mass of the molecule of concern. </li></ul><ul><li>Examples: </li></ul><ul><li>mass of 1 mole Na = 23.0 g Na </li></ul><ul><li>mass of 1 mole CO 2 = 44.0 g CO 2 </li></ul><ul><li>mass of 1 mole O 2 = 32.0 g O 2 </li></ul><ul><li>mass of 1 mole CO 3 2- = 60.0 g CO 3 2- </li></ul>
  8. 8. Chapter 6. (L22)-Chemical Accounting <ul><li>Introduction to mole and mass relationships in chemical reaction equations </li></ul><ul><li>The need for mole calculations in chemistry: </li></ul><ul><li>2H 2 + O 2 = 2H 2 O </li></ul><ul><li>? mole ? mole 4 mole </li></ul><ul><li>0.5 mole ? mole </li></ul><ul><li> 2 moles ? mole </li></ul>
  9. 9. Chapter 6. (L22)-Chemical Accounting <ul><li>Introduction to mole and mass relationships in chemical reaction equations </li></ul><ul><li>The need for mass calculations in chemistry: </li></ul><ul><li>2H 2 + O 2 = 2H 2 O </li></ul><ul><li>? g ? g 72 g </li></ul><ul><li>4 g ? g </li></ul><ul><li> 64 g ? g </li></ul>
  10. 10. Chapter 6. (L22)-Chemical Accounting <ul><li>Calculations of quantities of mole and mass in chemical equations: The principle of mole ratio </li></ul><ul><li>Molecule Formula Mass Molar Mass </li></ul><ul><li>H 2 2u 2g </li></ul><ul><li>O 2 32u 32g </li></ul><ul><li>H 2 O 18u 18g </li></ul><ul><li> </li></ul><ul><li>2H 2 + O 2 = 2H 2 O </li></ul><ul><li>2 molecules 1 molecule 2 molecules </li></ul><ul><li>2 moles 1 mole 2 moles </li></ul>
  11. 11. Chapter 6. (L22)-Chemical Accounting <ul><li>Calculations of quantities of mole and mass in chemical equations: The principle of mass ratio </li></ul><ul><li>Molecule Formula Mass Molar Mass </li></ul><ul><li>H 2 2u 2g </li></ul><ul><li>O 2 32u 32g </li></ul><ul><li>H 2 O 18u 18g </li></ul><ul><li> </li></ul><ul><li>2H 2 + O 2 = 2H 2 O </li></ul><ul><li>2 molecules 1 molecule 2 molecules </li></ul><ul><li>2 moles 1 mole 2 moles </li></ul><ul><li>4g 32g 36g </li></ul>
  12. 12. Chapter 6. (L22)-Chemical Accounting <ul><li>Molar relationships in chemical equations </li></ul><ul><li>Calculation example: </li></ul><ul><li>2H 2 + O 2 = 2H 2 O </li></ul><ul><li>2 moles 1 moles 2 moles </li></ul><ul><li>? moles ? mole 1.5 moles </li></ul><ul><li>? mole H 2 = 1.5 mole H 2 O ×2 mole H 2 /2 mole H 2 O </li></ul><ul><li>= 1.5 mole H 2 </li></ul><ul><li>? mole O 2 = 1.5 mole H 2 O ×1 mole O 2 /2 mole H 2 O </li></ul><ul><li>= 0.75 mole O 2 </li></ul>
  13. 13. Chapter 6. (L22)-Chemical Accounting <ul><li>Molar relationships in chemical equations </li></ul><ul><li>Calculation example: </li></ul><ul><li>2H 2 + O 2 = 2H 2 O </li></ul><ul><li>2 moles 1 mole 2 moles </li></ul><ul><li>? moles 2.5 moles ? Moles </li></ul><ul><li>? mole H 2 = 2.5 mole O 2 ×2 mole H 2 /1 mole O 2 </li></ul><ul><li>= 5.0 mole H 2 </li></ul><ul><li>? mole H 2 O= 2.5 mole O 2 ×2 mole H 2 O/1 mole O 2 </li></ul><ul><li>= 5.0 mole H 2 O </li></ul>
  14. 14. Chapter 6. (L22)-Chemical Accounting <ul><li>Mass relationships in chemical equations </li></ul><ul><li>Calculation example: </li></ul><ul><li>2H 2 + O 2 = 2H 2 O </li></ul><ul><li>4.0g 32g 36g </li></ul><ul><li>?g ?g 9.0g </li></ul><ul><li>? g H 2 = 9.0g H 2 O ×4g H 2 /36 g H 2 O </li></ul><ul><li>= 1.0 g H 2 </li></ul><ul><li>? g O 2 = 9.0 H 2 O ×32g O 2 /36g H 2 O </li></ul><ul><li>= 8.0 mole O 2 </li></ul>
  15. 15. Chapter 6. (L22)-Chemical Accounting <ul><li>Mass relationships in chemical equations </li></ul><ul><li>Calculation example: </li></ul><ul><li>2H 2 + O 2 = 2H 2 O </li></ul><ul><li>4.0g 32g 36g </li></ul><ul><li>?g 4.0g ?g </li></ul><ul><li>? g H 2 = 4.0g O 2 ×4.0g H 2 /32g O 2 </li></ul><ul><li>= 0.5g H 2 </li></ul><ul><li>? g H 2 O= 4.0g O 2 ×36g H 2 O/32g O 2 </li></ul><ul><li>= 4.5g H 2 O </li></ul>
  16. 16. Chapter 6. (L22)-Chemical Accounting <ul><li>Mass relationships in chemical equations </li></ul><ul><li>Calculation example: </li></ul><ul><li>C + O 2 = CO 2 </li></ul><ul><li>12.0g 32g 44g </li></ul><ul><li>10.0g ?g ?g </li></ul><ul><li>? g O 2 = 10.0g C ×32g O 2 /12g C </li></ul><ul><li>= 26.7g O 2 </li></ul><ul><li>? g CO 2 = 10.0g C ×44g CO 2 /12g C </li></ul><ul><li> = 36.7g CO 2 </li></ul>
  17. 17. Chapter 6. (L22)-Chemical Accounting <ul><li>Mass relationships in chemical equations </li></ul><ul><li>Calculation example: </li></ul><ul><li>Molar mass of NaN 3 : 65 g </li></ul><ul><li>Molar mass of N 2 : 28 g </li></ul><ul><li>2NaN 3 = 2Na + 3N 2 </li></ul><ul><li>130.0g 46.0g 84.0g </li></ul><ul><li>60.0g ?g </li></ul><ul><li>? g N 2 = 60.0g NaN 3 ×84g N 2 /130g NaN 3 </li></ul><ul><li>= 38.8g N 2 </li></ul>
  18. 18. Chapter 6. (L22)-Chemical Accounting <ul><li> Quiz Time </li></ul><ul><li>How many grams of water can be produced out of 8 g H 2 gas from the reaction: </li></ul><ul><li>2H 2 + O 2 = 2H 2 O </li></ul><ul><li>(a) 8.0 g H 2 O; </li></ul><ul><li>(b) 18.0 g H 2 O; </li></ul><ul><li>(c) 72.0 g H 2 O; </li></ul><ul><li>(d) 36.0 g H 2 O. </li></ul>
  19. 19. Chapter 6. (L22)-Chemical Accounting <ul><li> Quiz Time </li></ul><ul><li>How many moles of water can be produced out of 8 moles of CH 4 gas from the reaction: </li></ul><ul><li>CH 4 + 2O 2 = 2H 2 O + CO 2 </li></ul><ul><li>(a) 8.0 mole H 2 O; </li></ul><ul><li>(b) 32.0 mole H 2 O; </li></ul><ul><li>(c) 4.0 mole H 2 O; </li></ul><ul><li>(d) 16.0 mole H 2 O. </li></ul>
  20. 20. Chapter 6. (L22)-Chemical Accounting <ul><li> Quiz Time </li></ul><ul><li>How many grams of water can be produced out of 8 g of CH 4 gas from the reaction: </li></ul><ul><li>CH 4 + 2O 2 = 2H 2 O + CO 2 </li></ul><ul><li>(a) 8.0 g H 2 O; </li></ul><ul><li>(b) 32.0 g H 2 O; </li></ul><ul><li>(c) 16.0 g H 2 O; </li></ul><ul><li>(d) 18.0 g H 2 O. </li></ul>
  21. 21. Chapter 6. (L22)-Chemical Accounting <ul><li> Quiz Time </li></ul><ul><li>How many grams of ammonia can be produced out of 20.0 g of N 2 from the reaction: </li></ul><ul><li>3H 2 + N 2 = 2NH 3 </li></ul><ul><li>(a) 29.4 g N 2 ; </li></ul><ul><li>(b) 14.9 g N 2 ; </li></ul><ul><li>(c) 24.3 g N 2 ; </li></ul><ul><li>(d) 29.1 g N 2 . </li></ul>
  22. 22. Chapter 6. (L22)-Chemical Accounting <ul><li> Quiz Time </li></ul><ul><li>How many moles or grams of N 2 gas would be needed, respectively, to produce 1.25 moles of NH 3 from the reaction: </li></ul><ul><li>3H 2 + N 2 = 2NH 3 </li></ul><ul><li>(a) 0.625 mole or 6.5 g N 2 ; </li></ul><ul><li>(b) 1.0 mole or 1.0 g N 2 ; </li></ul><ul><li>(c) 0.625 mole or 1.75 g N 2 ; </li></ul><ul><li>(d) 0.625 mole or 17.5 g N 2 . </li></ul>

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