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Chem A Final Exam Review

Chem A Final Exam Review. In-class problem-solving. Set your totals equal to -1 since this is a -1 ion. Assign the most electronegative atom first. In this problem it is O. O usually has an oxidation state of -2. Since there are 3, total = -6.

norman-riggs
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Chem A Final Exam Review

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  1. Chem A Final Exam Review In-class problem-solving

  2. Set your totals equal to -1 since this is a -1 ion. • Assign the most electronegative atom first. In this problem it is O. O usually has an oxidation state of -2. Since there are 3, total = -6. • Assign H next. H usually has an oxidation state of +1. • S must be +4. (+1) + (+4) + (-6) = -1 1. Determine the oxidation state of S in HSO3-.

  3. Neutralization reaction. • Water and salt (LiF) • LiOH + HF H2O+ LiF 2. What are the products of the reaction between LiOH and HF? What type of reaction is this?

  4. m = mol of solute/kg of water • 0.1 = x/.225 • X = .0225 mol • .0225 mol X 40.00 g/mol = .90g 3. How many grams of NaOH should be added to 225g of water to produce a 0.10msolution?

  5. = 2 unpaired electrons • Electron configuration = 1s22s22p4 • Electron dot = O 4. How many unpaired electrons are in the ground state of oxygen?

  6. a. Atomic radius increases as you move down a family. 5. Which demonstrates the trend for increasing atomic radius?a. Li; Na; K orb. Ba; Sr; Ca

  7. 6. What is the difference between:Boiling/condensationSublimation/depositionMelting/freezing

  8. deposition Solid Liquid Gas condensation freezing melting evaporation sublimation Exothermic processes Endothermic processes

  9. Gas Melting (sl) Boiling (lg) Liquid Solid Heat curve – be able to label!

  10. 1. Be sure to convert so all units are the same. • 2. This is a significant figure problem. When adding or subtracting look at places past decimal. • 5.47g + .042g + 5.39g • =10.90g 7. Add 5.47 g, 4.2 cg and 5.39g

  11. 2 mol X (3 ions/1 mol) x (Avogadro’s #/1 mol) • = 3.6 x 1024ions 8. What is the total number of ions in 2.0 mol Cu(NO3)2?

  12. Reminders: • Write the charges of ions • The sum of the charges must equal 0 for a neutral compound • Magnesium cation = 2+ sulfate anion= 2- • Need one of each • OR • Write charges and use criss-cross rule. Like charges cancel out. Remember to reduce if able • Answer = MgSO4 9. What is the correct formula for magnesium sulfate?

  13. Al2(SO4)3 + 3Ca(OH)2 2Al(OH)3 + 3 CaSO4 10. Write a balanced equation of the reaction between aluminum sulfate and calcium hydroxide.

  14. Empirical formula = simplest whole-number ratio • C2H5 11. What is the empirical formula for C4H10?

  15. Boyle’s Law = P1V1 = P2V2; (765)(5.) = (700.) (x) = 5.5 L 12. A 5.0 L of krypton gas is at a pressure of 765 mmHg. At constant temperature what volume will the gas occupy if the pressure decreases to 700. mmHg?

  16. Answer = 1300g Fe (sig figs) • Balance equation. • Must have a mole:mole ratio • In order to achieve this you must use molar masses to convert to moles • Fe2O3 + 3CO  2 Fe + 3CO2 13. Use the following equation: Fe2O3 + CO Fe + CO2What mass of Fe is formed from 1800g of Fe2O3?

  17. FeSO4 .8H2O • 4 O in iron (II) sulfate • 8 O in water • Add! = 12 O • The dot just means water can be removed – do not multiply! 14. How many oxygen atoms are present in iron (II) sulfate octahydrate

  18. 15. How many liters of H2O (g) at STP will react with one mole of H2S?H2S + O2 H2O + SO2 Balance equation! 2H2S + 3O2 2H2O + 2SO2 Use 22.4 L = 1 mol Answer = 22.4 L

  19. Q = (m)(∆T)(Cp ) • 25000J = (m)(8)(3.42) • m = 914g 16. A sample of ethanol required 25 kJ of energy to be heated from 20.°C to 28°C . How many grams of ethanol were heated? Ethanol Cp = 3.42 J/g .°C.

  20. 17. A weak base is titrated with a known concentration of a strong acid. Sketch the titration curve. Based on equivalence point. Above 7 = strong base/weak acid At 7 = strong base/strong acid Below 7 = weak base/strong acid Graph on next slide

  21. Starting Solution: weak base • Added Standard: strong acid • 14 • 7 • equivalence point (below 7)  • 1 • 10 20 30 40 Titration curve weak base/strong acid

  22. B. Remember atomic radius! Decreases as you go left to right, increases as you go down. All other trends are opposite!!! 18. Choose the series of elements that increases in electronegativity.a. Rb, Cs, Fr b. N, O, F

  23. Sulfur • Atomic # = 16 • Atomic mass = 32 • proton # = Atomic # =16 • Neutron# = Mass # - Atomic # = 16 • Electrons = protons in a neutral atom. Add 2 electrons to make this ion = 18 electrons 19. Calculate p+, n0, and e- in S 2-.

  24. 20. Is HSO4- acting as an acid or a base in this equation?HSO4- + H2O ↔ SO4-2 + H3O+ HSO4- is the acid because it donates a hydrogen ion (H+)

  25. Multiply each mass by abundance (move decimal 2 places to left) • Add your product – do NOT divide by 3! • Answer = 27 21. What is the atomic average atomic mass of the following isotope?Atomic Mass % Abundance26 66.628 15.730 17.7

  26. 3 half-lives go by • Sample is 300 years old 22. The half-life for candium = 100 years. If 12.5% of a sample remains, how old is the candium sample?

  27. Ksp = [Fe2+][NO3-]2 23. Write the Ksp expression for Iron (II) nitrate (s).

  28. Reminders: • Products – Reactants • If products have more energy than the reactants, the value is positive and the reaction is endothermic. • If the products have less energy than the reactants, the value is negative and the reaction is exothermic. 24. What is the H for the reaction A B? (see diagram on board)

  29. % to mass • Mass to moles • Divide by smallest • Multiply until whole • = Na2SO3 25. A compound is 36.5% sodium, 25.4% sulfur, and 38.1% oxygen. What is the empirical formula? If the molecular mass is 252, what is the molecular formula?

  30. D = mass/volume • L x w x h = volume; then mass object • Mass the object and then use a graduated cylinder to determine water displacement. 26. Describe how you would determine the density of cube of copper 1.0 cm on each side? How would determining density of an irregular object differ?

  31. [H3O] = 10-pH • = 2.0 x 10-6 27. Calculate [H3O+] for a substance with a pH of 5.7.

  32. pH = -log[H3O+] • pH = 4.5 • pH + pOH = 14 • pOH = 9.5 28. What is the pH and pOH of a solution if the [H3O+] is 3.4 x 10 -5M?

  33. “like dissolves like” • Polar solutes dissolve in polar solvents and nonpolar solutes dissolve in nonpolar solvents • Water is a known polar compound • The oils must be non-polar. 29. Mineral oil dissolves in canola oil but does not dissolve in water. What is the reason for this?

  34. Propane – 3 carbons, all single bonds Propene – 3 carbons, 1 double bond 30. Name the following: H HHHHHH-C - C - C-H H-C = C -C-H H HHH

  35. a. = trigonal planar • b.= tetrahedral • c. = trigonal pyramidal • F B F H • F H C H N • H HHH 31 What is the molecular geometry of the following? a. BF3 b. CH4 c. NH3

  36. a. Dissociation factor is 3. the d.f. in b is one and the d.f. in c is 2. in equal amounts, magnesium bromide will have the greater effect. 32. Which has a greater effect on the melting point of ice? a. MgBr2 b. CH2H5OH c. KCl

  37. Carbon dioxide 33. Which molecule is nonpolar?a. CO2 b. NaCl c. NH3

  38. alpha 34. What particle is omitted when Po-210 changes to Pb-206?

  39. 5.90 moles 35. How many moles are in 236 g of NaOH?

  40. Nickel (II) phosphate 36. What is the IUPAC name for Ni3(PO4)2?

  41. 22.99/40.00 X 56g • = 32 g 37. How many grams of Na are in 56 g of NaOH?

  42. Cu(NO3)2 (aq) + Zn (s) Zn(NO3)2(aq) + Cu(s) • OIL RIG • Zn must lose electrons to form ion so it is being oxidized. Cu 2+ is oxidizing agent 38. Consider the following reactants:Cu(NO3)2 (aq) + Zn(s)Predict productsBalance equationWhat is the oxidizing agent?

  43. A couple of extra questions: Do Now • What force holds two different water molecules closely together? • What is the difference between accuracy and precision? • How do you physically separate a mixture like… • Sand & water • Alcohol and water • Who diffuses more quickly H2 or F2?

  44. reaction coordinate for a catalyzed reaction. • What is the normal activation energy? • What is the catalyzed activation energy? • What is the enthalpy of the reaction (ΔH)? • Is this reaction endothermic or exothermic? ________________

  45. Identify which way the reaction will shift in the given scenarios:

  46. Organic Review Alcohols • General formula: R-OH • Ex: CH3CH2-OH Carboxylic Acid • General Formula: R – COOH • Ex:

  47. Ether • General Formula: R- O – R • Ex: Esters • General Formula: R – COO – R • Ex:

  48. Alkanes • CnH2n+2 • Alkenes • CnH2n • Alkynes • CnH2n -2

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