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Homework 2 due today- in class Homework 3 posted. Due Wednesday 7 Feb Fong Lab book return

This is the homework assignment for Chemistry class focusing on significant figure calculations. The topics covered include adding/subtracting, multiplying/dividing, and combinations of both operations. Additionally, the big picture of chemistry and naming inorganic compounds is introduced.

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Homework 2 due today- in class Homework 3 posted. Due Wednesday 7 Feb Fong Lab book return

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  1. Homework 2 due today- in class Homework 3 posted. Due Wednesday 7 Feb Fong Lab book return

  2. Calculations done to correct sig fig Adding/subtracting The decimal count of the least precise value determines the calculation’s decimal count…. 3.1 3.001 + 0.1 + 0.01 =_____ 16 14.5- 0.100 + 2 = _____

  3. 1.00+50.1+ 0.100= • 51.200 • 51 • 51.2 • 51.20

  4. 400 + 2.0 -1.999 +0.03= ? • 400 • 400.03 • 400.0 • 400.031

  5. Calculations done to correct sig fig (cont.) Multiplying/dividing The value with the lowest sig fig count dictates the calculation’s sig fig count 9 11*0.9=_____ 5.1000*0.211 1.0 (10.1/2.000) =______ 5.0*0.99876

  6. Calculations done to correct sig fig (continued) Combos of Multiplying/dividing with adding/subtracting Do +/- first to correct count; then x and / to lowest sig fig count 3.1 3.001 + 0.1 + 0.01 = _______ 1.5000*2.00 = 1.0 3.00

  7. One more mixed operation example: U-Do-It 9.0 9.0 + 0.10 + 0.001 = 1.5000*2.00 = 3.0 3.00

  8. What is the correct value to report for the product: (5.000 + 3.0)/1.9999? • 4 • 4.0000 • 4.0 • 4.000

  9. What is the correct value for the mixed calculation: 10.00 - (3.0*2.000/1) • 4.0 • 4 • 4.000 • 4.00

  10. Had enough ??

  11. Finally, we’re done with the stinking bit with numbers for a while…. NOW…(WAIT FOR IT)… TIME FOR CHEMISTRY!

  12. Chemistry…the big picture

  13. Chemistry:Yes or No ? IN-CLASS DEMOS Chemistry: Yes or No ? • No • No • No • Yes • Yes • Cutting up paper • Hammering salt • Ice melting • Burning paper • Sodium in water

  14. Chemical change=> you can’t go home again.

  15. The BIG PICTURE behind what makes Chemistry has two parts (sect. 2.2 ) Part 1 R. Boyle (1627-1691) Everything is composed of elements. Elements cannot be changed to other elements chemically

  16. Boyle’s elements: 1805 …elements defined by mass • All atoms of a given element weigh the same. • Atoms of different elements are distinguished by differences in their weight.

  17. Initial Shape of Periodic Table Arranging Boyle’s Elements 1869

  18. Modern Periodic Table 2016

  19. J. Dalton (1766-1844) (section 2.2) Part 2 Elements combine in whole-numbered ratios of `atoms’ to form compounds. Compounds react by reorganizing how the atomsare combined (bound) together.

  20. Elements defined `operationally’ (the experimentalist’s definition): An element cannot be made to lose weight by any possible chemical process. Lab looking for elements in 1780 A scale is always present

  21. The Big Picture parts 1 and 2 in Pictures Chemistry is ~ about the scrambling of elemental combinations from one form to another.

  22. The demos written as reactions: Burning paper: C12H20O10 + 12O2 12CO2 + 10H2O Sodium in water: 2Nao + 2H2O(l)  2NaOH(aq) + H2(g) Explosion can happen 2H2+O2 2H2O ignited by initial reaction heat…a reaction begetting another reaction.

  23. Even Bigger (Hotter) Reactions… Thermite Reaction Fe2O3 + 2Al  2Fe + Al2O3 https://www.youtube.com/watch?v=CWMATrOatRw

  24. Example of a Typical Organic Reaction Sequence N-methylphenyl-2-propan-2-amine Street name: Crystal meth

  25. Naming Inorganic compounds: in-class practicing metals Non-metals Transition metals Lanthanides Actinides

  26. Extension of Stock naming system to Oxyanions Many elements react with O to form stable, negatively charged `oxyanions’ Examples: ClO- ClO2- Hypochlorite Chlorite ClO3- ClO4- Chlorate perchloric Cl- chloride SO32- SO42- Sulfite sulfate S2O32- S4O62- Thiosulfate tetrathionate S2- sulfide

  27. Common Oxyanions: names, formulas, charges (List found at Course website under Laboratory)

  28. Oxyanions (OXY) are treated and named just like NM M +NM M + OXY Na+ + Cl- Na+ + ClO3- NaCl NaClO3 Sodium chloride Sodium chlorate TM +NM TM + OXY Fe3+ + Cl- Fe3+ + ClO3- FeCl3 Fe(ClO3)3 Iron(III) chlorate Iron(III) chloride

  29. In-class Board practice with OXYANIONS

  30. What is the correct name for S2F4? • Sulfur fluoride • Sulfur(II) fluoride • Disulfur tetrafluoride • Sulfur tetrafluoride

  31. What is the correct name for Ca3As2 • Tricalcium diarsenide • Calcium arsenide • Calcium (III) Arsenic(II) • Calcium arsenic

  32. What is the correct name for ZnO? • Zinc(II) oxide • Zinc monoxide • Zinc oxide • Monozinc monoxide

  33. What is the correct formula for Copper(II) Acetate? • Cu(C2H3O2) • Cu2(C2H3O2) • Cu(C2H3O2)2 • Cu(C3H2O3)

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