CHEM120 Week 5 Exam 2 (Units 3 and 4) – With 100% Correct Answers- Download To Score An A+

Document Content and Description Below

CHEM120 Week 5 Exam 2 (Units 3 and 4) – With 100% Correct Answers- Download To Score An A+ Exam 2 Total Points: 60 PART 1: Multiple Choice questions: Q 1-24. (2 point each) 1. Chemical ... reactions (equations) show the following a. Reactants b. Products c. Physical state of each (gas or liquid or solid) d. All of the above 2. The following is true for a mole a. It is also known as Avagadro’s number b. It contains 6.022 * 1023 molecules c. It contains mass equivalent to molecular weight d. All of the above are true 3. In balancing chemical equations, the coefficients are used to a. Show number of moles b. Show volume of each in liters c. Show amount of each in grams d. Show temperature at which the substance is stable 4. 2H2 + O2 2H2O means that a. 2 grams of H2 g and 1 gram of O2 gas combine to form 2 grams of water. b. 2 moles of H2 g and 1 mole of O2 gas combine to form 2 moles of water. c. 2 grams of H2 g and 1 gram of O2 gas combine to form 2 moles of water. d. 2 molecules of H2 g and 1 molecule of O2 gas combine to form 2 molecules of water. 5. 2H2 + O2 2H2O. In this equation, correct method to calculate molecular mass of water is a. 2[2(mass of hydrogen) + mass of oxygen] b. 2(mass of hydrogen gas) + mass of oxygen gas c. 2(mass of hydrogen) + mass of oxygen 1 6. One mole of O2 gas contains number of molecules. a. 32 Grams b. 1 c. 6.02 * 1023 d. None of the above 7. Concentration of a solution is a. Amount of solute dissolved in given amount of solvent b. Amount of solute dissolved in 1 L of solvent c. 1 g of solute dissolved in given amount of solvent d. A mass equivalent to Molecular weight of solute dissolved in given amount of solvent 8. The following is a product of reaction of a nonmetal oxide with water to make acid. a. C6H12O6 b. H2CO3 c. NH4OH d. CO2 9. If CaO reacts with water, the following product will be made. a. Ca b. CaOH c. Ca(OH)2 d. H2Ca 10. The following will be made when KOH reacts with HCl. a. KH b. KCl c. H2O d. B & c are true 11. “The neutralization reaction is a quantitative reaction, where amount of acid needed to neutralize the base can be accurately calculated.” This statement is a. True b. False 12. The pH scale represents the a. acidity of a solution b. whether the acid is strong acid or weak 2 c. amount of salt d. all of the above 13. Buffer solution is a solution a. With constant concentration b. With constant pH c. Of weak base d. All of the above 14. Oxidation is defined as . It occurs on a/an . a. Gain of electron; anode b. Gain of oxygen; anode c. Gain of hydrogen; Cathode d. Gain of electron; Cathode 15. Reduction is defined as . It occurs on a/an . a. Gain of electron; Cathode b. Gain of oxygen; Cathode c. Loss of hydrogen; Anode d. Loss of oxygen; Anode 16. Oxidizing agents cause . During that process they themselves are . a. Oxidation, reduced b. Reduction, oxidized c. Oxidation, oxidized d. Reduction, reduced 17. Reducing agents cause . During that process they themselves are . a. Oxidation, reduced b. Reduction, oxidized c. Oxidation, oxidized d. Reduction, reduced 18. Silver tarnish is an example of a. Oxidation b. Reduction 3 19. Oxygen is a . a. Oxidizing agent b. Reducing agent 20. Photosynthesis combines CO2 and H2O into glucose via a series of reactions. a. Oxidation b. Reduction 21. Cellular Respiration generates CO2 and H2O from glucose via a series of reactions. a. Oxidation b. Reduction 22. The following is true for Boyle’s law. a. At constant temperature, pressure is inversely proportional to volume. b. At constant temperature, pressure is directly proportional to volume. c. At constant pressure, temperature is inversely proportional to volume. d. At constant pressure, temperature is directly proportional to volume. 23. The following is true for Charles’s law. a. At constant temperature, pressure is inversely proportional to volume. b. At constant temperature, pressure is directly proportional to volume. c. At constant pressure, temperature is inversely proportional to volume. d. At constant pressure, temperature is directly proportional to volume. 24. At STP, what would be the molar mass of a gas with density of 2.1g/L? a. 10.6 g/mole b. 47 g/mole c. 0.094 g/mole d. 2.1 g/mole PART 2: Write units and show ALL work. 25. Calculate the molarity of a 250 ml solution containing 420g Aluminum hydroxide (2 points). MW of Al(OH)3 = 78 g/mole Moles of Al(OH)3 = mass/MW = 420 g/ 78 g/mole = 5.38 moles Volume = 250 mL x 1 L /1000 mL = 0.25 L M = moles /Vol in L = 5.38 moles/ 0.25L = 21.54 M 4 26. 0.5 M stock solution of NaCl was diluted to 50 mM solution in 350 ml volume. Calculate the volume needed to make this dilution. (2 points) 0.5 M x 1000 mM/1M = 500 mM C1V1 = C2V2 V1 = C2V2/C1 = (50 mM x 350 mL)/500 mM = 35 mL 27. (a) Complete and balance the reactions given below. (b) Answer the given question (5 points). a. 3 Ba + 2 H3PO4 Ba3(PO4)2 + 3 H2 Metal Acid Salt Hydrogen gas b. Calculate the amount in gram of acid needed to produce 50 g of Salt. MW of salt Ba3(PO4)2 = 601.2 g/mole MW of acid (H3PO4) = 98 g/mole Mass of given  moles of given 50 g salt Moles = mass/ MW = 50g/ 601.92 g/mole = 0.0831 moles of salt (given) moles of given  moles of unknown (USING BALANCED EQUATION) 0.0831 moles of given (salt) x 2 moles acid (unknown)/1 mole salt (given) = 0.166 moles of acid (unknown) moles of unknown  mass of unknown moles of unknown = 0.166 MW of H3PO4 = 98 g/mole Moles = mass /MW Mass = Moles x MW 5 Mass of unknown = moles of unknown x MW of unknown = 0.166 moles x 98 g/moles = 16.28 g 28. Calculate the pressure, in atmospheres, of 9.81 mol CO(g) in a 7.5 L tank at 35 degrees C. (3 points) T = 273 + C = 273 + 35 = 308 K PV = nRT P = nRT/V = (9.81 x 0.082 x 308)/7.5 = 33.03 atm 6 [Show More]

Last updated: 1 year ago

Preview 1 out of 6 pages