You Try: Give the correct number of significant digits for the following: a cm b. 170 g c sec

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1 Mid-term Review- Chemistry Name January 2012 Kids Have Dropped Over Dead Converting Metrics Metric Conversions: Example: Convert 50.0 grams to kg You Try: If a building has a height of mm, what is its height in kilometers? Significant Digits (Figures) The only problem was determining when the zeros are significant. Remember that FINAL zeros AFTER the decimal are significant and zeros between two SD are significant. Example: 6060 meters grams You Try: Give the correct number of significant digits for the following: a cm b. 170 g c sec Scientific Notation: General formula M x 10 n Where 1 M < 10 and n is a positive or negative whole number. (integer) Example: = 5 x = x 10-3 You Try: Change the following into Scientific Notation: a b c Math and Significant Digits: Add/Subtract: Least number of decimal places Multiply/Divide: Least number of significant digits Example: times 63 You Try: a plus b X 10 7 times 1.3 X 10 3 Density is mass (grams) divided by volume (ml or cm 3 ) You Try: The density of magnesium is 1.74 g/cm 3. What is the mass, in grams, of a piece of magnesium having a volume of cm 3? Dimensional Analysis or the Factor Label method This is the chart we have used all year. You Try: Convert inches to exameters. (1 in = 2.54 cm, 100 cm = 1m 1 exameter = 1 x meters) 1

2 The one conversion factor we have memorized: You Try: A bucket has a capacity of 9.75 Liters, how many cm 3 of water can it hold? Classify the following as heterogeneous mixture, solution, compound or element a. Titanium d. Air b. Sucrose, (C 12 H 22 O 11 ) e. Salt water c. Granite Classify as a Physical or Chemical change. a. Burning Wood d. Growing a Tree b. Dissolving Salt e. Digging a Hole c. Boiling Water Classify as a Physical or Chemical property. a. Density d. Color b. Length e. Freezing Pt. c. Odor f. Flammability NAME the following compounds: a. NH 4 ClO 3 e. P 2 O 3 b. Mg 3 (PO 4 ) 2 f. NaClO 2 c. Fe (OH) 3 g. PbO d. Cu(CN) 2 h. NiCO 3 WRITE the formula for the following compounds: a. Nitrogen Dioxide e. Chromium (III) Sulfate b. Aluminum Oxide f. Sodium Nitrate c. Copper (II) Iodate g. Lead (II) Carbonate d. Strontium Permanganate h. Hydrogen Hydroxide Why do you need a roman numeral in naming some compounds? 2

3 What is the oxidation state of the underlined element? 1. FeS 4. Fe(NO 3 ) 3 2. CoBr 2 5. PbSO 4 3. HgI 2 Avagadro s number is used to calculate the number of molecules or formula units 6.02 X molecules = 1 mole Example: You Try: 9.32 x ions of Li 2 S to grams 35.5 moles of AgCl to formula units 6.85 X molecules I 2 to moles 4.59 X atoms H 2 O to molecules Molarity is a measure of concentration; It is equal to moles of solute divided by liters of solution. MOLES MOLARITY LITERS You Try: What is the molarity of a solution containing 596 grams of NaCl in 5.00 x 10 2 cm 3 of solution? In an experiment you start with 3.00 L of a M NaCl solution. If you boil the water out of the solution, how many grams should you end up with? How many grams are in 50.0 ml of a 3.25 M solution of NaCl? How many moles should you add to a ml volumetric flask to make a 1.5 M NaCl solution? Percentages are found by dividing the part by the whole Example: Find the % of O in Fe 2 O 3 3

4 You Try: Determine the % of carbon in Al 2 (CO 3 ) 3. Empirical Formula is the lowest whole number mole ratio. Example: What is the Empirical formula of a compound that is 81.9 % Ta and 18.1 % O? You Try: What is the Empirical formula of a compound that is 43.5 % Phosphorus and 56.5 % Oxygen? The molecular formula is a multiple of the empirical. Example: What is the molecular formula of a compound if the empirical formula is N 2 O 3 and the molecular mass is g/mol? You Try: What is the molecular formula of the compound if the empirical formula is NO 2 and the molecular mass is 92.0 g/mol? Hydrates are similar. They include a mole ratio between a compound and water. Example: A gram sample of hydrated Lanthanum Carbonate is heated and the water is driven off. The dry sample has a mass of grams. What is the formula of the hydrate between La 2 (CO 3 ) 3 and H 2 O? You Try: A hydrate contains 90.7 % SrC 2 O 4 and 9.30 % H 2 O. What is its formula? You Try: What is the percentage of water in Mo 2 P 5 * 3 H 2 O? Balance the following equations: 1. (NH 4 ) 2 SO 4 + NaOH NH 3 + H 2 O + Na 2 SO 4 2. Ba(CN) 2 + H 2 SO 4 BaSO 4 + HCN 3. Pb(NO 3 ) 2 PbO + NO 2 + O 2 Give the type of reaction: 1. Al 2 (CO 3 ) 3 Al 2 O 3 + CO 2 2. HgS + Ca 3 (PO 4 ) 2 Hg 3 (PO 4 ) 2 + CaS 3. I 2 + Cl 2 ICl 3 4

5 4. MgI 2 + O 2 I 2 + MgO 5. Cl 2 + LiH LiCl + H 2 Write the formulas, state the type of reaction, predict the products, and balance. Don t forget to use the activity series and the solubility rules. If there is no reaction, write NO RXN. 1. Chlorine + Calcium Bromide 2. Copper (I) Sulfate + Lead (II) Nitrate 3. C 5 H 10 + O 2 4. Oxygen + Barium 5. Strontium Hydroxide Stoichiometry: Convert to moles, use the mole ratio, Convert to the unit asked for in the problem. Example: How many grams of Copper are required to react with 45.0 grams of Silver Nitrate? Cu + 2 AgNO > Cu(NO 3 ) Ag Example: When 20.0 liters of Calcium Hydroxide reacts, how many moles of Ammonia, NH 3, are produced? (NH 4 ) 2 SO 4 + Ca(OH) > CaSO NH H 2 O You Try: Excess chlorine reacts with 92.5 liters of I 2. Calculate the grams of ICl 3 produced. I Cl > 2 ICl 3 You Try: A student reacts 2.50 grams of KI with 5.30 grams of Pb(NO 3 ) 2 2 KI + Pb(NO 3 ) > PbI KNO 3 What are the maximum number of grams of PbI 2 that can be produced? You Try: How many liters of CO 2 can be produced from 35.5 liters of C 5 H 11 OH? 2 C 5 H 11 OH + 15 O 2 10 CO H 2 O 5

6 Old Review Quizzes Mid-term Review- Quiz one Name Form A January 12, The circumference of the earth is meters at the equator. A. Put it in scientific notation (in meters) showing 4 significant digits. B. Convert this measurement to kilometers. C. Convert it to miles. (1 mile = 1609 meters) 2. NAME the following compounds: A. NH 4 Cl C. Ni(NO 3 ) 3 B. Al 2 (SO 4 ) 3 D. CuO 3. WRITE the formula for the following compounds: A. iron (III) phosphate C. diphosphorous trioxide Sulfate = SO 4-2 Hydroxide = OH -1 Nitrate = NO 3-1 Carbonate = CO 3-2 Phosphate = PO 4-3 Ammonium = NH 4 +1 B. lithium carbonate D. calcium hydroxide grams of CCl 4 to atoms (molar mass = 154 g/mol) Mid-term Review- Quiz two Name Form A January 16, Find the % of Oxygen in Pb(S 2 O 3 ) 2 6. Find the empirical for a compound that contains 66.0 % Ca and 34.0 % P. 7. Give the type of reaction, predict the products and balance the reactions: A. Cl 2 + Li 2 O B. NaNO 3 + Mg(IO 3 ) 2 C. C 5 H 12 + O 2 8. How many grams of Na are needed to produce 86.9 g of NaCl? 2 Na + Cl 2 2 NaCl 9. Convert Liters of H 2 gas at STP to moles. 6