? CHE 145 B5z1 Lab Exam I Name_____________________ Direction: Answer the questions and show your work in the space provided. 1. Convert the following numbers to standard exponential form: a) 0. 00352 _____3. 52×10-3__ __ b) 0. 01847 _____1. 847×10-2____ c) 7,604 ________7. 604x103__ _ d) 536. 2 x 105 ____5. 362×107 _______ 2. How many significant figures are there in the following: a) 0. 10849 ________5_________ b) 0. 864 _______3_______ c) 6024 _________4________ d) 35. 9 x 105 ______3________ 3.
Add or subtract as indicated. Express to the proper number of significant figures. a) 15. 20 + 0. 015 + 6. 321 = __21. 54__ b) 6. 42 + 4. 41 – 44 = ___-33___ c) 600 – 107. 6 = _____492___ d) 75. 2 + 175 – 75. 03 = __175___ 4. Multiply or Divide the following problems. Round to the correct number of significant figures. a) (64. 69)(8. 08) = ______523 ___ b) 0. 7406/0. 144 = ____5. 14_____ c) (354. 43)(4. 596) = ___ _77. 12____ d) 345. 67/9. 01 = _____38. 4_____ Page 2 5. Write the names of the chemicals shown by their formulas/or the ormulas from the given names. a) BaCl2 ____barium chloride_____ b) KMnO4 __potasium permanganate c) H2SO4 ____sulphuric acid______ d) H2O ______hydrogen oxide____ e) AgNO3 ____silver nitrate______ f) Sodium bicarbonate ______Na2CO3____ g) Nitric acid _________HNO3________ h) Hydrochloric acid _________HCl_______ i) Potassium dichromate _______K2CrO4____ j) Sodium hydroxide __________NaOH____ 6. Complete the following conversion factors or problems: a) 1 cm3. = __1___ mL. 1 kg. = _1000___ g. 10 cm. = __100__ mm. ) Convert 6. 54 ft to centimeters: 199. 339 c) Convert 100. 02 milligrams to pounds: (Use scientific notation for your final answer). 2. 205 x 10-4 7. Write a balanced chemical equation to represent each of the following reactions: a. The decomposition, by heating, of solid mercury(II) nitrate to produce pure liquid mercury, nitrogen dioxide gas, and oxygen gas. 2MgNO3 –> 2 Mg + 2N02 + O2 b. The reaction of aqueous sodium hydroxide with aqueous hydrochloric acid (hydrogen chloride) to produce water, and aqueous sodium chloride.
NaOH + HCl –> H2O + NaCl 8. Calculate the molecular weight of LiC2H3O2. 65. 985 g/mol 9. Calculate the mass of 0. 625 moles of LiC2H3O2. 41. 24g 10. In an experiment to test how well methyl alcohol works as an antifreeze, a technician collected a sample of 170. 50 mL of this liquid. Its density is 0. 810 g/mL. How many grams of methyl alcohol were taken? 138. 11g 11. A sample of substance X weighs 115. 9 g. Initially at a temperature of 23. 5 oC, its temperature rises to 58. 6 oC. If substance X is found to have a heat capacity of 0. 15 cal/g oC, how much heat was absorbed by the substance? 8746. 39 12. Balance the following equations by inspection. Mark the correct coefficient in the space provided. NOTE: While we normally do not write coefficients which equal one in a chemical equation, for the purpose of this exam, please do so. a. __2_ Mg + _1 _ O2 ? __2_ MgO b. __3_ CaBr2 + __2_ H3PO4 ? __1_ Ca3(PO4)2 + __6_ HBr c. _1__ Al(OH)3 + _3__ HNO3 ? _1__ Al(NO3)3 + _3__ H2O d. _2__ C4H10 + _13__ O2 ? __8_ CO2 + _10__ H2O e. _2__ Al + __6 _ HCl ? __2__ AlCl3 + __3__ H2
