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Study guide for Part 1 of Final Exam

Study guide for Part 1 of Final Exam. A 1000 watt iron produces 1000 joules (1 kilojoule) of energy per second. How many kilocalories of energy is generated in one hour? (1 calorie=4.184 joules) 1000 joules|1 cal | kilo |60 sec|60 min= 860 kcal sec |4.184 J| 1000 |1 min |1 hr

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Study guide for Part 1 of Final Exam

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  1. Study guide for Part 1 of Final Exam • A 1000 watt iron produces 1000 joules (1 kilojoule) of energy per second. How many kilocalories of energy is generated in one hour? (1 calorie=4.184 joules) • 1000 joules|1 cal | kilo |60 sec|60 min= 860 kcal sec |4.184 J| 1000 |1 min |1 hr • How many atoms of chlorine is in dinitrogen tetrachloride? • What volume of oil will have the same mass at 51 mL of mercury? (oil density= 0.90 g/mL, mercury density=13.6 g/mL) • 51 mL |13.6 g =693.6 g693.6 g |1 mL = 771mL | mL |0.90g

  2. Know acid names and formulas: Hydrochloric acid, Nitric acid, Nitrous acid, Sulfuric acid, sulfurous acid, Phosphoric acid • Physical change versus chemical change • Physical change is a change from solid to liquid or a liquid to gas. • A chemical change is coming apart or combining with other elements or compounds. Burning, rusting, decomposing, reacting with other compounds are examples.

  3. Precision versus accuracy • If your measurements are close to each other, you have precision. If they match a known or expected value, then you have accuracy. • Know pure element, compound, and mixture. • An element is made of just one kind of atom. O2 is and element even though there are two of them together. • A compound is two or more elements combined. Visually you would see two different atoms (spheres) joined. • A mixture are two or more compounds mixed but not bonded together. Visually, you would see more than one kind of atom or molecule separate from each other. O O O C N N O C

  4. Know charge on polyatomic ions like chlorates, sulfates, carbonates, phosphates • Know a precipitation reaction • NaCl(aq) + AgNO3(aq)  AgCl(s) + NaNO3(aq)

  5. What is produced when alkali metals or alkaline earth metals are placed in water. • Na + H2O  or write • 2Na(s) + 2HOH(l) 2NaOH(aq) + H2(g) • What is difference between total ionic equation and net ionic equation? • Top is total ionic, bottom is net ionic • Na+(aq) + Cl-(aq) + Ag+(aq) + NO3-(aq) AgCl(s) + Na+(aq)+ NO3-(aq) • Cl-(aq) + Ag+(aq) AgCl(s)

  6. Figuring oxidation number of metals combined with non-metals such as 6A, & 7A non-metals. CuS, TiF4, TiO2, MnO4-. • Always start with the oxidation number of the non-metal. Sulfur and oxygen are -2. • Copper is 2+, Ti is 4+ for both, and Mn is +7. • What would neutralize acids? Hydroxides (OH-) or carbonates (CO32-). • Solubility rules. • Sulfates are soluble except for barium and lead. Chlorides, bromides, and fluorides are soluble except for silver, lead, and mercury.

  7. Given moles of one compound in a reaction, give moles of the others. • 2KClO3 2KCl + 3O2 • 0.245 moles O2 |2 mol KClO3 = 0.163 moles KClO3 |3 mol O2 • Discern excess or insufficient quantities in a reaction. • 2Al + 3Cl2 2AlCl3 (57 g Al & 200g of Cl), which reactant has an excess and how much? • 54 g Al |1 mol= 2.1 mol Al |27 g • 200 g Cl|1 mol = 5.6 mol Cl or 2.8 mole Cl2 |35.6 g • 2.1 mol Al | 3 mol Cl2 = 3.15 mol Cl2 | 2 mole Al • 2.8 mol Cl2| 2 mol Al = 1.87 mol Al| 3 mole Cl2 • 2.8 moles of Cl2 can is only enough to react with 1.87 mol Al. Since there are 2.1 moles of Al, there is 0.23 (2.1-1.87) moles of Al in excess. For grams that’s 0.23 mol x 27g/mole = 6.2 grams.

  8. Figure % yield • 12 grams of calcium chloride is reacted with an excess of sodium carbonate to make 9.5 grams of calcium carbonate. What was the % yield? • CaCl2(aq) + Na2CO3(aq) CaCO3(s) + NaCl(aq) • 12 g CaCl2| 1 mol = 0.11 molCaCl2 | 111 g • 9.5 g CaCO3| 1 mol = 0.095 molCaCO3 | 100 g • 0.11 mol CaCl2 should produce 0.11 mole of CaCO3 however, it only produced 0.095 moles. So the fraction of what it did produced over what it should have is 0.095/0.11 = 86% yield. • Equipment to make up a specific molar solution. • Moles per Liter. To find moles we need a balance. To measure liter accurately, we use a buret or a volumetric flask. But to make molar concentratons, a compound is placed in some water and the level brought up to one liter. So a volumetric flask is the best. • Evidence of reactions (heat, precipitate, gas, color change)

  9. Percent mass of one element in a compound • KMnO4, --- What is percent mass of manganese? • K = 39 g/mol, KMnO4 = 158 g/mol. % = 39/158 = 0.25 or 25% • Balance a combustion reaction. • C5H8O3 + O2 CO2 + H2O • Balance carbons with CO2 first, and hydrogen with water. Do O2 last. • Basic dilution problem. • Conc x Vol =Conc x Vol • Concentrated = Diluted • How many mL of 2.5 molar solution of HCl is needed to make up 350 mL of 0.1M HCl? • Concentrated = Diluted • 2.5 M x ?mL = 0.1M x 350 mL • Divide both sides by 2.5M to have mL= 0.1Mx350mL/2.5M • ?mL = 14 mL

  10. Moles of one element in a compound, knowing the compounds mass and formula. • 24 grams Na2SO4, how many moles of sulfur is there? • 24 g Na2SO4| 1 mol = 0.169 molNa2SO4 | 142 g • Since there’s one sulfur in sodium sulfate, then the moles of sulfur is the same as the sodium sulfate. • Knowing energetic light has shorter wavelength and higher frequency. Radio waves, infrared, visible light, ultraviolet, x-rays, gamma rays. Which has the shortest wavelength, which has highest frequency? Gammas rays are the shortest wavelength and the highest freqeuncy.

  11. Heat of formation: page 244, 242 • Bond energies: page 341 for table, page 349 for problem. • Electron configuration page 301, 302

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