CHM2045 Exam 1 Review Questions Fall 2015

Transcription

1 1) Which of the chemical formulas are written correctly? a. Magnesium Dichloride MgCl 2 b. Phosphorus Pentafluoride PF 5 c. Sodium Chloride NaCl 2 d. Potassium Bromide KBr e. Monocarbon Monoxide CO f. Dinitrogen Trioxide N 2O 3 2) Which of the following is false? a) Iron(III) sulfide has three Fe atoms b) HCl is a strong acid c) Z is the atomic number symbol d) NO 3 is nitrogen trioxide 3) Which of the following is closest to the mass of chromium in g Cr 2O 3? a) g b) g c) g d) g 4) Compound X contains the following elemental mass percent: 54.51% C, 9.156% H, and 36.33% O. The molecular weight is g/mol. Which choice is a possible molecular formula for compound X? Bonus: What is the Empirical Formula? a) C 2H 4O b) C 3H 5OH c) C 3H 7COOH d) C 3H 7CHO 5) A g sample of ZnSO 4 xh 2O is dissolved in an aqueous solution of BaCl 2. The pure BaSO 4 precipitate is filtered out of solution, dried, and its mass is determined to be g. What is the value of x in ZnSO 4 xh 2O?

2 6) How many grams of sodium hydroxide are needed to make 250 ml of a M NaOH? 7) Balance the following equation: FeBr 3 + H 2SO 4 Fe 2 (SO 4 ) 3 + HBr 8) Please find the oxidation numbers for each element of the following reaction (rxn) Fe 2O 3 + 3CO 2Fe + 3CO 2 9) Which of the following are redox rxns? a) Na + (aq) + Cl - (aq) NaCl (aq) b) KNO 3 (s) 2 K 2O(s) + 2 N 2(g) + 5 O 2(g) c) CH 4 + 2O 2 CO 2 + 2H 2O

3 10) Given the reaction: 3 H 2S + 2 FeCl 3 = Fe 2S HCl We have 60.0 g of FeCl3 reacts with 42.0 g of H 2S. Which is the limiting reactant. Also, what is the mass of HCl produced and what is the percent yield? 11) Name or write the acids correctly a) HCl b) Hydro Iodic Acid c) HC 2H 3O 2 d) Chlorous Acid e) HBr f) H 2SO 4 12) Name or write the bases correctly a) NaOH b) KOH c) NH 3 d) Ca(OH) 2 13) How many sodium atoms are contained in 1.00mL of M aqueous sodium sulfite?

4 14) In which of the following equations is the acid (proposed acid is underlined) incorrectly labeled? HCl + H 2O Cl - + H 3O + H 2PO H 2O H 3PO 4 + OH - CN - + H 2O HCN + OH - CH 3COOH + H 2O CH 3COO - + H 3O + HCO H 2O H 2CO 3 + OH - 15) If volumes are additive and ml of 0.60 M sodium chloride is mixed with 120 ml of a calcium chloride solution to give a new solution in which [Cl -1 ] is 0.34 M, what is the concentration of the calcium chloride used to make the new solution? 16) A scientist added 70.0 ml of a sodium hydroxide solution to ml of M HCl. The resulting solution was then treated with an excess of aqueous chromium (III) nitrate, resulting in the formation of 3.06 g of precipitate. Determine the concentration of the initial sodium hydroxide solution.

5 17) Aqueous potassium iodide reacts with aqueous copper(ii) nitrate to form a mixture of solid copper(i) iodide, solid iodine, and aqueous potassium nitrate. What volume of a M solution of aqueous potassium iodide will contain enough potassium iodide to react exactly with the copper(ii) nitrate in ml of a M solution of aqueous copper(ii) nitrate? 18) Describe the following terms a) Polyatomic Ion b) Molarity c) Acid d) Base e) Redox Reaction f) Combustion Reaction g) Precipitation Reaction h) Acid-base Reaction

6 19) Select the false statement below (a) Pb 2+ (aq) + 2I (aq) PbI 2(s) is a precipitation reaction but is not a redox reaction (b) CH 4(g) + 2O 2(g) CO 2(g) + 2H 2O(g) is a combustion reaction and a redox reaction (c) Ca(s) + F 2(g) CaF 2(s) is a precipitation reaction and a redox reaction (d) HNO 3(aq) + KOH(aq) H 2O(l) + KNO 3(aq) is an acid-base reaction but is not a redox reaction (e) H 2SO 4(aq) + Ba(OH) 2(aq) 2H 2O(l) + BaSO 4(s) is a precipitation reaction and an acid-base reaction 20) Sweetener saccharin (C 7H 5NO 3S) is sometimes dispensed in tablet form. Ten (10) tablets with a total mass of g were dissolved in water. They were oxidized to convert all the sulfur to sulfate ion, which was precipitated by adding an excess of barium chloride solution. The mass of barium sulfate obtained was g. What is the average mass percent of saccharin in the tablets?

7 GOOD LUCK ON THE EXAM AND GET A GOOD NIGHT SLEEP THE NIGHT BEFORE TEST! -Broward Teaching Center