Chem 1212 Lab Final Exam Study Guide latest updated questions and Answers, Exams of Chemistry

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Chem 1212 Lab Final Exam Study Guide latest updated questions and Answers what must you do before coming to the lab? - CORRECT ANSWER-take the lab quiz, write the chemical alert table in the lab notebook, review the chemicals and their hazards, read the experiment, prepare the lab notebook for the experiment which of the following items of clothing are appropriate to wear in CHEM 1212 lab to protect your skin ? - CORRECT ANSWER-lab apron, t-shirt, scrub pants, jeans which of the following are appropriate to wear in CHEM 1212 Lab to protect your feet? - CORRECT ANSWER-boots, loafers, or tennis shoes/sneakers where is the eye wash station located? - CORRECT ANSWER-mounted on the wall next to the large sink chemical causes dryness, itching, or sensitivity - CORRECT ANSWER-irritant irreversibly destroys living tissue or metal upon contact - CORRECT ANSWER- corrosive may cause harm through ingestion, inhalation, or skin absorption - CORRECT ANSWER-toxic chemical proved to cause cancer - CORRECT ANSWER-carcinogen excess chemicals disposal method - CORRECT ANSWER-appropriate waste container used filter paper disposal method - CORRECT ANSWER-trash can reaction mixture disposal method - CORRECT ANSWER-appropriate waste container cracked or chipped beaker disposal method - CORRECT ANSWER-broken glass box what if a person's hair catches on fire? - CORRECT ANSWER-wrap with fire blanket and stop, drop, and roll what if a chemical spills on your leg? - CORRECT ANSWER-remove affected clothing and rinse with water for 15 minutes what if a chemical gets in your eyes? - CORRECT ANSWER-flush with eye-wash solution for 15 minutes what if a chemical spills on your hand? - CORRECT ANSWER-rinse with water for 15 minutes what should you do if you spill a chemical on your lab bench? - CORRECT ANSWER- clean it up using the spill kit in your lab. can you eat or drink in the lab? - CORRECT ANSWER-no when is it okay to remove your chemical splash proof goggles? - CORRECT ANSWER- when everyone in the lab has put away all chemicals and glassware What is the density of a solid that occupies a volume of 5.89 mL and weighs 5.14 g? - CORRECT ANSWER-density = mass/volume 5.14 g/5.89 mL = 0.873 g/mL sugar disappears when added to hot tea. what describes the relationship between sugar and tea? - CORRECT ANSWER-soluble what will result when water (density = 1.0 g/mL), liquid M (density = 0.65 g/mL, immiscible with H2O), and liquid N (density = 0.80 g/mL, immiscible with M and H2O) are poured into test tube. - CORRECT ANSWER-three layers will form in the test tube. water is the bottom layer, liquid N is middle layer, and liquid M is the top layer. the ability for a gas or solid to dissolve in a liquid - CORRECT ANSWER-solubiliy mass to volume ratio - CORRECT ANSWER-density the ability for two liquids to mix together - CORRECT ANSWER-miscibility A + B → AB represents... - CORRECT ANSWER-combination ABC → AB + C represents.... - CORRECT ANSWER-decomposition AB + C → B + AC represents.... - CORRECT ANSWER-single displacement AB + CD → AD + BC represents... - CORRECT ANSWER-double displacement A + B → A+n + B-m represents... - CORRECT ANSWER-oxidation-reduction amount of product recovered in an experiment - CORRECT ANSWER-actual yield the amount of product produced if the experiment was 100% efficient - CORRECT ANSWER-theoretical yield actual yield over theoretical yield times 100 - CORRECT ANSWER-percent yield equation for the moles of analyte - CORRECT ANSWER-M(titrant) x equiv. pt. vol. titrant x (mol analyte/ mol titrant) = moles analyte predict the conductivity of NH2CH2CH2NH2, a weak base. - CORRECT ANSWER- weak electrolyte predict the conductivity of H3BO3, a weak acid - CORRECT ANSWER-weak electrolyte Is H2SO4 a strong or weak acid? - CORRECT ANSWER-strong acid/strong electrolyte Is BaSO4 a strong/weak/nonelectrolyte? - CORRECT ANSWER-nonelectrolyte pressure equation - CORRECT ANSWER-P(total) = PO2 + PH2O ideal gas law - CORRECT ANSWER-PV=nRT What is the Molarity of the Ba(OH)2 solution if a 12.50 mL aliquot of the Ba(OH)2 solution required 15.20 mL of a 0.108 M H2SO4 solution to reach the equivalence point? - CORRECT ANSWER-15.2 mL x 0.108 M x (1/1000) = 0.00164 0.00164 x (1/15.20) x 1000 mL = 0.131 M In this experiment, you will be using and measuring various chemical species by a variety of units. Which units of measure is used for the temperature of water? - CORRECT ANSWER-Kelvin In this experiment, you will be using and measuring various chemical species by a variety of units. Which units of measure is used for the volume of O2(g)? - CORRECT ANSWER-mililiters In this experiment, you will be using the gas constant, R. Which unit is NOT found in R? - CORRECT ANSWER-Molarity dilution equation - CORRECT ANSWER-Conc(stock) x Vol(stock) = Conc(dilute) x Vol(dilute) absorbance equation - CORRECT ANSWER-slope x concentration ppm equation - CORRECT ANSWER-ppm = mg of solute/L of solution A calibration plot of absorbance vs. concentration (ppm) was obtained with standard known Red 40 dye solutions. The slope of the best-fit straight line of the plot is 0.038 ppm- 1 The absorbance of the dilute unknown sports drink was 0.64 What is the concentration of thisdilute unknown sports drink? - CORRECT ANSWER- 16.8 ppm An 10.0 mL aliquot of a 125 ppm stock Red 40 dye solution was diluted to a final volume of 25.0 mL with deionized water. What is the concentration of the dilute Red 40 dye solution (in ppm)? - CORRECT ANSWER-50 ppm A 75.0 mg sample of Red 40 dye was dissolved and diluted to a final volume of 1.25 L with deionized water. What is the concentration of the Red 40 dye solution in ppm? parts per million (ppm) refers to 1 mg of solute in 1.0 L of solution (mg/L) - CORRECT ANSWER-60 ppm Ozzie wanted to do another experiment with a stronger H2O2 solution to check the accuracy of the experiment by calculating the theoretical volume of O2(g) it would produce. Then he could compare his experimental volume of O2(g) to the theoretical volume of O2(g). He used 5.20 mL of 2.21 M H2O2 and the partial pressure of O2 was 0.9341 atm and the temperature was 298.35 K. What volume of O2(g) could he theoretically produce (in mL)? - CORRECT ANSWER-150 mL An unknown compound Z dissolves completely in water, yet does not dissociates into ions. Which conductivity classification do you predict for Z? - CORRECT ANSWER- nonelecrolyte An unknown compound Y dissolves completely in water and partially dissociates into ions. Which conductivity classification do you predict for Y? - CORRECT ANSWER- weak electrolyte An unknown compound X dissolves completely in water and dissociates completely into ions. Which conductivity classification do you predict for X? - CORRECT ANSWER- strong electrolyte in experiment 3, what color/state was Cu? - CORRECT ANSWER-reddish copper/solid in experiment 3, what color/state was CuSO4? - CORRECT ANSWER-bright blue/aqueous solution in experiment 3, what color/state was Cu(OH)2? - CORRECT ANSWER-dark blue/solid in experiment 3, what color/state was Cu(O)? - CORRECT ANSWER-black(dark brown)/solid Which statement best explains what happens to the percent yield if the crystals (product) were washed with hot water? - CORRECT ANSWER-The actual yield will decrease since part of the product will dissolve and not be recovered as a solid.Since actual yield is in the numerator, the percent yield will also decrease. Nick and Kel reacted 2.80 g of NiCl2· 6 H2O with 7.00 mL of 4.00 M C2H8N2. They recovered 2.40 g of product, [Ni(C2H8N2)3] Cl2.At the end, the filtrate was a dark blue solution. The litmus test on the filtrate solution left the red litmus paper unchanged in color. NiCl2· 6 H2O + 3 C2H8N2 → [Ni(C2H8N2)3]Cl2(s) + 6 H2O Molar Mass of NiCl2· 6 H2O is 237.69 g/mol Molarity of C2H8N2 is 4.00 M Molar Mass of product, [Ni(C2H8N2)3]Cl2(s) is 309.90 g/mol Limiting reagent? Excess reagent? Actual yield? Theoretical yield? - CORRECT ANSWER-C2H8N2 NiCl2 6H2O 2.40 g 2.89 g In experiment 4, what color is expected for the filtration if NiCl2·6 H2O is the limiting reagent? If C2H8N2 is? - CORRECT ANSWER-pink - NiCl2·6 H2O dark violet - C2H8N2 For the procedural error, indicate if the error will affect the actual yield of [Ni(C2H8N2)3]Cl2 product and if it does, will it raise or lower the actual yield: Weighed the product while the product was still wet - CORRECT ANSWER-Raises the actual yield For the procedural error, indicate if the error will affect the actual yield of [Ni(C2H8N2)3]Cl2 product and if it does, will it raise or lower the actual yield: Rinsing the product with 10 mL of acetone instead of 5 mL in step 11 - CORRECT ANSWER-No effect Here is useful information for the questions below.Select your answers from the pull- down menus. C12H7O2NCl2 is abbreviated as DCIP Molar Mass of C6H8O6(s) is 176.14 g/mol What is the mole fraction (Χ) of CH3OH, methanol, in a solution of 8.75 mL of CH3OH and 3.77 g of C6H5COOH, benzoic acid ? Density of methanol is 0.792 g/mL Molar mass of CH3OH is 32.04 g/mol Molar mass of C6H5COOH is 122.12 g/mol Select one: 0.750 0.900 0.875 0.850 0.800 - CORRECT ANSWER-0.875 What is the vapor pressure (in kPa) of CH3OH, methanol, over a solution which is composed of 7.50 mL of methanol and 3.23 g of C6H5COOH, benzoic acid, at 25ºC ? Pº methanol at 25ºC = 16.915 kPa Density of methanol is 0.792 g/mL Molar mass of benzoic acid is 122.12 g/mol Select one: 16.79 kPa 15.20 kPa 13.78 kPa 14.80 kPa - CORRECT ANSWER-14.80 kPa Callie, Gay, & Steve were discussing the results of this experiment in terms of general trends. Which statement below is TRUE ? Select one: a) As the mole fraction of solvent became smaller, the Psolvent was raised as compared to P°solvent. b) As the mole fraction of solvent became smaller, the Psolvent remained relatively the same as P°solvent. c) As the mole fraction of solvent became smaller, the Psolvent was lowered as compared to Pºsolvent - CORRECT ANSWER-c) As the mole fraction of solvent became smaller, the Psolvent was lowered as compared to Pºsolvent What is the vapor pressure (in kPa) of ethanol, CH3CH2OH, over a solution which is composed of 27.50 mL of ethanol and 14.38 g of benzoic acid, C6H5COOH, at 35ºC ?Enter your number with two digits past the decimal. Pºethanol at 35ºC = 13.693 kPa Density of ethanol = 0.789 g/mL, Molar mass of ethanol = 46.07 g/mol Molar mass of benzoic acid = 122.12 g/mol - CORRECT ANSWER-10.95 Raoult's Law works for other units of pressure, such as atm, mmHg, and torr. The only requirement is that both vapor pressures have the same units. Predict the vapor pressure (in torr) of carbon tetrachloride, CCl4, over a solution which is composed of 300.00 g of CCl4 and 123.76 g of I2 at 65ºC. Submit your answer with 1 digit past the decimal. PºCCl4 at 65ºC = 531 torr Molar mass of CCl4 is 153.81 g/mol Molar mass of I2 is 253.8 g/mol - CORRECT ANSWER-424.8 Select the appropriate word that matches the definition below. A solid compound that forms as a result of mixing reagents together in a solution. Select one: a) supernate b) precipitate c) centrifuge d) decantate - CORRECT ANSWER-b) precipitate Select the appropriate word that matches the definition below. The liquid above the solid in a mixture of solid and solution. Select one: a) centrifuge b) precipitate c) supernate d) decantate - CORRECT ANSWER-c) supernate NH3 (aq) and NH4OH (aq) are different ways of writing the chemical formula of the which chemical ? Select one: a) nitric acid b) aqueous ammonia c) monoamide d) ammonium ion - CORRECT ANSWER-b) aqueous ammonia You have two test tubes. One test tube contains Pb+2 (aq) solution and the other test tube contains Cu+2(aq). Predict what will happen when HCl (aq) is added to both test tubes.If a reaction occurs, what is the new chemical fomula? Select one: a) Pb+2 (aq) will remain unchanged. & Cu+2 (aq) will form a white precipitate, Cu2Fe(CN)6 (s). b) Pb+2 (aq) will remain unchanged. & Cu+2 (aq) will form a blue solution, [Cu(NH3)6]+2 (aq). c) Pb+2 (aq) will form a white precipitate, PbCl2 (s). & Cu+2 (aq) will remain unchanged. d) Pb+2 (aq) will form a yellow precipitate, PbCrO4 (s). & Cu+2 (aq) will remain unchanged. - CORRECT ANSWER-c) Pb+2 (aq) will form a white precipitate, PbCl2 (s). & Cu+2 (aq) will remain unchanged. Match the confirmation test with a description of the positive results. a) Confirmation test for Pb+2 : b) Confirmation test for Ag+: - CORRECT ANSWER-a) a yellow precipitate b) a white precipitate Match the confirmation test with a description of the positive results. a) Confirmation test for Cu+2: b) Confirmation test for Bi+3: - CORRECT ANSWER-a) a maroon precipitate b) a black solid You have one test tube which contains a colorless solution that is either Cu+2 (aq) or Pb+2(aq). Select a reagent that will allow you to differentiate between the two chemical species. If the solution is Cu+2, what will happen when the reagent is added?If the solution is Pb+2, what will happen when the reagent is added? Select one: a. K2CrO4If it is Cu+2, a yellow precipitate will form after adding the K2CrO4. If it is Pb+2, the solution turns yellow, but no solid will form after adding the K2CrO4. b. HClIf it is Cu+2, a white precipitate will form after adding the HCl.If it is Pb+2, the solution will remain the same after adding the HCl. c. hot waterIf it is Cu+2, the solution will remain the same after adding the hot water.If it is Pb+2, a white precipitate will form after adding the hot water d. HClIf it is Cu+2, the solution will remain the same after adding the HCl.If it is Pb+2, a white precipitate will fo - CORRECT ANSWER-d. HClIf it is Cu+2, the solution will f) The presence of a light blue decantate in step 1-A. g) A white precipitate did not form in step 2-B. h) A lack of dark blue colored solution after addition of 15 M NH3. i) The white solid did not turn black upon addition of NaOH and SnCl2. - CORRECT ANSWER-g) A white precipitate did not form in step 2-B. Select the step(s) that will compose a rationale for the cation Cu+2 being present in an unknown. Select one or more: a) The white solid turned black upon addition of NaOH and SnCl2. b) The white precipitate from step 1-B dissolved in 6 M NH3 and then reformed when 6 M HNO3 was added. c) A white precipitate formed in step 2-B. d) The formation of a dark blue solution in step 2-B. e) All of the white precipitate from step 1-A dissolved in hot water. f) A white precipitate formed when 6 M HCl was added to the unknown solution in step 1-A. g) Dark blue solution turned to light blue in step 2-D after the addition of CH3COOH and then h) A yellow precipitate formed when K2CrO4 was added in step 1-C. i) A reddish brown precipitate formed after adding K4Fe(CN)6 in step 2-E. - CORRECT ANSWER-d) The formation of a dark blue solution in step 2-B. g) Dark blue solution turned to light blue in step 2-D after the addition of CH3COOH and then i) A reddish brown precipitate formed after adding K4Fe(CN)6 in step 2-E. When 4.51 g of CaCl2 dissolved in 50.00 mL of water in a coffee cup calorimeter, the temperature of the solution rose from 22.6°C to 25.8°C. Specific heat of the solution is equal to the specific heat of water = 4.18 J/gºC Density of the solution is equal to the density of water = 1.00 g/mL What is qsolution? What is qreaction ? What is ΔHrxn in kJ/mol of CaCl2 - CORRECT ANSWER-qsolution = (+)729 J qreaction = (-)729 J ΔHrxn = (-) 17.9 kJ/mol In a certain reaction, a solid chemical dissolved in water. The temperature of the water sample dropped from 27.3°C to 22.4°C. Select all the statements that are true about this experiment. Select one or more: a) qsurroundings is a (+) value. b) Heat was gained by the surroundings. c) The reaction is endothermic. d) The water is defined as the surroundings. e) qsystem is a (-) value. f) The water is defined as the system. g) Heat was gained by the system. h) The reaction is exothermic. - CORRECT ANSWER-c) The reaction is endothermic. d) The water is defined as the surroundings. g) Heat was gained by the system. A coffee cup calorimeter contained 50.0 mL of a 1.33 M KOH solution at an initial temperature of 22.8 ºC. A student quickly add 50.0 mL of 1.17 M HNO3 to the calorimeter. The maximum temperature reached during the neutralization reaction was 28.6ºC. Determine the ΔHrxn for this neutralization reaction in kJ/mol of HNO3. (assume specific heat of solution is the same as specific heat of water = 4.18 J/gºC) (assume density of both KOH and HNO3 are the same as water = 1.00 g/mL) (if negative value, be sure to type in a minus sign.) HINT: You will need to first find qsolution. - CORRECT ANSWER--41.4 If an error caused the final temperature to be larger, how does this affect the calculation of the heat of solution (qsolution)? Select one: a) The larger Tfinal would produce a larger ΔT, which would result in a smaller q. b) The larger Tfinal would produce a larger ΔT, which would result in a larger q. c) The larger Tfinal would produce a smaller ΔT, which would result in a smaller q. d) The larger Tfinal would produce a smaller ΔT, which would result in a larger q. - CORRECT ANSWER-b) The larger Tfinal would produce a larger ΔT, which would result in a larger q. For the following error, select the answer that correctly describes how it will affect the value of the final temperature of the water/solution in the calorimeter: As the aluminum rods were added, the calorimeter was knocked over and some of the water was spliled. The aluminum rods were still covered, but the total volume of water was less. Select one: a) Decreases the value of final Temperature b) Increases the value of final Temperature c) No affect - CORRECT ANSWER-b) Increases the value of final Temperature Select all that apply to an exothermic reaction. Select one or more: a) The reaction absorbs heat from the surroundings. b) Adding heat (hot water bath) will cause the equilibrium to shift towards products. c) Removing heat (cold water bath) will cause the equilibrium to shift toward products. d) The reaction releases heat to the surroundings. e) Heat is a reactant. - CORRECT ANSWER-c) Removing heat (cold water bath) will cause the equilibrium to shift toward products. d) The reaction releases heat to the surroundings. Consider the benzoic acid dissociation reaction below which is at equilibrium. C6H5COOH (aq) + H2O(ℓ) ⇋ C6H5COO- (aq) + H3O+(aq) b) Increasing the overall total pressure of the equilibrium system. - CORRECT ANSWER-a) will shift the equilibrium toward the products b) will shift the equilibrium toward the reactants A 2.50 mL aliquot of a 0.10 M HCl solution is diluted to a final volume of 25.00 mL. What is the molarity of this first dilution solution? Then a second dilution was made by taking 8.00 mL of the first dilution and diluting it to 50.00 mL. What is the molarity of this second dilution? Select one: a) 1st Dilution = 0.100 M; 2nd Dilution = 4.00 x 10-3 M b) 1st Dilution = 0.0100 M; 2nd Dilution = 1.60 x 10-3 M c) 1st Dilution = 0.0100 M; 2nd Dilution = 6.40 x 10-3 M d) 1st Dilution = 0.0400 M; 2nd Dilution = 6.40 x 10-3 M - CORRECT ANSWER-b) 1st Dilution = 0.0100 M; 2nd Dilution = 1.60 x 10-3 M What is the pH of a 0.20 M HCl solution? Select one: 1.61 1.16 0.70 0.91 - CORRECT ANSWER-0.70 What is the pH of a 1.8 x 10-2 M NaOH solution? Select one: 9.98 11.73 11.10 12.26 - CORRECT ANSWER-12.26 write the correct definition or example of the following terms: a) Acidic buffer b) Brønsted-Lowry base c) Buffering capacity - CORRECT ANSWER-a) a mixture of a weak acid and the salt of its conjugate base b) any substance that receives a proton c) the amount of acid or base that can be added before the pH changes by 1 pH unit using the sample data below, answer the questions below. E + D → B + A Rate of reactionAve. Init. RateTRIAL[D] M[E] M (kPa/sec)A0.4000.4005.40 x 10- 3B0.4000.2002.72 x 10-3C0.8000.4001.10 x 10-2 a) What is the reaction order of D ? b) What is the reaction order of E ? - CORRECT ANSWER-a) 1 b) 1 What is the average value of k (rate constant) for the data set below.Previously it was determined that the reaction was 1st order in E and 3rd order in D. Enter your value of k with 3 digits past the decimal. Rate of reaction Ave. Init. Rate TRIAL [D] M [E] M (kPa/sec) A 0.400 0.400 5.40 x 10-3 B 0.400 0.200 2.74 x 10-3 C 0.800 0.400 4.37 x 10-2 - CORRECT ANSWER-0.213 Predict the initial rate (in kPa/sec) for Trial D using the data below.It was previously determined that the reaction is 1st order in D, 3rd order in E, and the average rate constant, k is equal to 0.280 kPa/(sec · M4). Enter your Initial Rate with 3 significant figures. Rate of reaction Ave. Init. Rate TRIAL [D] M [E] M (kPa/sec) A 0.300 0.400 5.40 x 10-3 B 0.300 0.200 6.83 x 10-4 C 0.600 0.400 1.05 x 10-2 D 0.200 0.600 - CORRECT ANSWER-0.0121 Consider the half reactions below and determine the overall reaction. Cu(s) → Cu+2(aq) + 2 e - NO3-(aq) + 4 H+(aq) + 3 e - → NO(g) + 2 H2O a) How many electrons are transferred in the oxidation half-reaction? b) How many electrons are transferred in the reduction half-reaction? c) How many electrons are transferred in the overall reaction? - CORRECT ANSWER- a) 2 b) 3 c) 6 Ferris & Mona used the ORP sensor to titrate a ferrous ammonium sulfate solution, (NH4)2Fe(SO4)2 with KMnO4 titrant. They titrated a 15.00 mL aliquot of the Fe+2 solution with 0.0250 M MnO4- solution and determined that the equivalence point was at 20.2 mL. What is the molarity of the Fe+2 solution? 5 Fe+2(aq) + MnO4-(aq) + 8 H+(aq) → 5 Fe+3(aq) + Mn+2(aq) + 4 H2O Select one: a. 0.0337 M b. 0.673 M c. 0.168 M d. 0.0928 M - CORRECT ANSWER-c. 0.168 M Sully, Fay & Tia worked together on the redox titration of Fe+2 with MnO4- (Part I). Fay & Tia used the equivalence point volume of MnO4- as determined from titration graph. However, Sully used the volume of MnO4- when the solution first turned brown, which was a smaller volume than Fay & Tia's volume. Will Sully's calculations of the molarity of Fe+2 be different than Fay & Tia's calculation? How and why? Select one: a. Sully's M of Fe+2 will be higher than the other two students.Since the volume of MnO4- is in the numerator for the calculation of M of Fe+2, the lower volume of MnO4- results in higher M of Fe+2. b. Sully's M of Fe+2 will be higher than the other two students.Since the volume of MnO4- is in the denominator for the calculation of M of Fe+2, the lower volume of MnO4- results in higher M of Fe+2. c. No difference.It is the same titration, so all 3 students should have the same answer. d. Sully's M - CORRECT ANSWER-d. Sully's M of Fe+2 will be lower than the other two students.Since the volume of MnO4- is in the numerator for the calculation of M of Fe+2, the lower volume of MnO4- results in lower M of Fe+2.