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CHM2045L: Final Exam (Pre-Lab Quizzes Compiled)
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SOME QUESTIONS WITH GRAPHS ARE NOT INCLUDED BC IT DEPENDS ON THE GRAPH GIVEN. The questions not included are listed here: 2 questions from Density, 2 questions from Stoichiometry,
Terms in this set (51)
Melanie obtains a value of 3.238 g/mL for the density of her unknown solution. The actual density of the solution is 1.048 g/mL.
What is the % error of Melanie's measurement? Express your response to two digits after the decimal.
a. 210.43
b. 354.93
c. 208.97
d. 204.678
(experimental-actual)/actual*100%
(3.238-1.048)/1.048*100%=208.97
A student obtains the following data:
Mass of empty, dry graduated cylinder: 28.926 g
Volume added of NaCl solution: 3.795 mL
Mass of graduated cylinder + NaCl solution: 46.856 g
What is the density of the solution? Express your answer to 3 digits after the decimal.
a. 4.3
b. 4.725
c. 4.624
d. 4.301
(46.856-28.926)/3.795=4.725
d=m/v
Jason measures three values of density for his unknown. The values he obtains are:
1.524 g/mL
1.149 g/mL
1.705 g/mL
What is the average of his three measurements? Express your response to three digits after the decimal.
a. 1.63
b. 1.45
c. 1.57
d. 1.70
(1.524+1.149+1.705)/3=1.459
A student is told the theoretical mass % water in her sample is 65.806 %.
She obtains an experimental value of 46.172 % when she performs the lab activity.
What is her % error?
Report your answer to three digits after the decimal.
a. 32.654
b. 76.923
c. 29.836
d. 32.451
(65.806-46.172)/65.806*100%=29.836
Sam records the mass of his evaporating dish as 6.158 g.
He records the mass of the evaporating dish and the sample of hydrate as 17.096 g.
After heating the sample in the evaporating dish to constant weight, the mass of them combined is 11.327 g.
How many moles of water were removed from the sample by the heating process?
Report your answer with three digits after the decimal.
a. 0.321
b. 0.320
c. 0.333
d. 0.322
hydrate=17.096-6.158=10.938,
after heating(dehydrate)=11.327-6.158=5.169, water=10.938-5.169=5.769, mole=5.769/18=0.320
An anhydrous (water removed) salt has a formula mass of 246.263 g/mol. If the hydrated version of the salt has 8 mol of water associated with it, what is the mass % of water in the hydrated salt?
Report your answer to three digits after the decimal.
a. 37.2
b. 36.020
c. 36.919
d. 43.3
water=8*18.02=144.16
hydrate=144.16+246.263=390.423 mass %=144.16/390.423*100%=36.92
A student heats a sample of hydrate once, and the mass of the sample and the evaporating dish is 16.324 g. After a second heating cycle, the mass of the sample and the dish is 15 g. The student stops the heat/cool/weigh cycle after the second time.
If the original mass of the evaporating dish and the hydrate was 28.169 g, and the mass of the evaporating dish alone was 1.937 g, what is the mass of water removed from the sample by heating?
Provide your response to three digits after the decimal.
a. 13.2
b. 13.333
c. 13.169
d. 13.954
28.169-15=13.169
George determines the mass of his evaporating dish to be 9.317 g. He adds a solid sample to the evaporating dish, and the mass of them combined is 18.063 g. What must be the mass of his solid sample? Express your response to three digits after the decimal.
a. 8.743
b. 8.744
c. 8.745
d. 8.746
18.063-9.317=8.746
A titration is performed as follows:
16.328 mL of Fe2+ solution of unknown concentration is charged into a 100 mL beaker.
45 mL of deionized water is added
the solution is titrated with 0.538 M Ce4+ solution
the equivalence point is reached after 4.829 mL of Ce4+ solution is added
What is the concentration of the Fe2+ solution? Report your response to three digits after the decimal.
a. 0.155
b. 0.142
c. 0.159
d. 0.1311
Fe2+ and Ce4+ react 1:1
M
V(Fe2+) = M
V(Ce4+)
M
16.328=0.538
4.829
M=0.159
A solution of citric acid of unknown concentration, prepared in deionized water, is titrated with standardized sodium hydroxide solution, also in deionized water. A few drops of phenolphthalein is added to visualize the pH change. Phenolphthalein changes color from colorless to pink between pH of 7 - 9.
What is the titrant in this titration?
What is the analyte in this titration?
titrant: sodium hydroxide
analyte: citric acid
What is the equation of a line, in slope-intercept form, that connects the following two data points?
(5.0, 1200)
(6.0, -850)
Enter your answer by filling in the following blanks. Enter each of your answers as whole numbers without any rounding.
y=____x + ____
(find m & b)
a. m= 2050 b= 10320
b. m= -2050 b= 21330
c. m= -2050 b= 11450
c. m= 2050 b= 21443
m = -850-1200/(6-5)=-2050
b = 11450 带入点计算
A student performs an experiment where gas is collected over water in an upside down graduated cylinder. If the atmospheric pressure is 734 mmHg and the level of water in the graduated cylinder is 12.9 cm higher than the level of the water exposed to the atmosphere, what is the total pressure of gases inside the graduated cylinder?
Enter your answer numerically in units of mmHg.
a. 734.32
b. 724.51
c. 749.32
d. 781.63
Pg=Patm - pgh = 734-(1000
9.81
0.129*0.0075)=724.509
乘以0.0075因为 1kg/ms-2 = 0.0075 mmHg
A student collects hydrogen gas over water in a graduated cylinder. If the student measures that the total pressure inside the graduated cylinder is 0.921 atm and the experiment was performed at 25 C, what is the pressure of hydrogen gas?
Enter your answer numerically in units of atm. (Vapor pressure of H2O @ 25 C = 0.0313 atm)
a. 0.89
b. 0.43
c. 0.52
d. 0.14
Ptotal = 0.921 = Ph2 + Ph2o
At 25 C, Ph2o=0.0313
Ph2 = 0.921-0.0313=0.8897
A student measures the pressure, volume, and temperature of a gas in the laboratory and records the following data:
P = 0.301 atm, V = 112 mL, T = 300 K
Based on this information, what would be the volume of the gas at STP?
Enter your answer to three significant figures in units of mL.
a. 33.2
b. 30.7
c. 31.4
d. 35.6
STP condition: P= 1atm, T = 273K
P1V1/T1 = P2V2/T2
(0.301
112)/300=(1
V2)/273
V2=30.67
If 0.243 g of Mg are reacted with 10.0 mL of 3 M HCl, how many moles of H2 should be produced theoretically?
Enter your answer numerically in units of moles.
a. 0.1
b. 0.01
c. 0.001
d. 0.0001
Mg + 2HCl = MgCl2 + H2
0.243/24.305=0.01 mole Mg = 0.01 mole H2
If 5.58 moles of gas are produced in an experiment and it is measured that they occupy 112 L at STP, what is the experimental molar volume of the gas?
Enter your answer numerically in units of L/mol.
a. 20.96
b. 21.34
c. 20.07
d. 24.32
STP condition: P= 1atm, T = 273K
PV=nRT, R= 0.082, n= mole
1
V= 5.58
0.082*273=124.914L (112L没有超过124)
112/5.58=20.07
Standard heats of formation for reactants and products in the reaction below are provided.
2 HA(aq) + MX2(aq) → MA2(aq) + 2 HX(l)
SubstanceΔHf° (kj/mol):
HA(aq): -477.823
HX(l): -35.341
MA2(aq): 309.282
MX2(aq): 87.803
What is the standard enthalpy of reaction, in kJ? Report your answer to three digits after the decimal.
a. 1,105.443
b. 1,106. 443
c. 1,107,443
d. 1,109.443
1,106.443
margin of error +/- 0.05
A coffee cup calorimeter is prepared, containing 100.000 g of water (specific heat capacity = 4.184 J/g K) at initial temperature 80.000 C. A salt weighing 7.067 g is quickly added. The salt has a molar mass of 492.452 g/mol. The final temperature of the solution is 24.153 C.
Assume no heat loss to the surroundings. Assume the specific heat capacity of the solution is equal to that of pure water, and that the mass of the solution is equal to the mass of the solid plus the mass of water in the calorimeter.
What is the molar heat of solution for the salt, in kJ/mol?
Report your answer to three digits after the decimal.
a. 1,744.57
b. 1,732.757
c. 1,743.315
d. 1,735.38
1,743.315
1,743.3154 margin of error +/- 1%
A 312 g sample of a metal is heated to 305.448 °C and plunged into 200 g of water at a temperature of 11.594 °C. The final temperature of the water is 76.1 °C. Assuming water has a specific heat capacity of 4.184 J/g °C, what is the specific heat capacity of the metal sample, in J/g °C)? Assume no heat loss to the surroundings.
Report your response to 3 digits after the decimal.
a. 0.7431
b. 0.7543
c. 0.8430
d. 0.7926
0.754
0.7543 margin of error +/- 0.05
Suppose you are investigating the reaction: M(s) + 2 HCl(aq) → MCl2(aq) + H2(g).
You weigh out a 0.263 gram piece of metal and combine it with 70.8 mL of 1.00 M HCl in a coffee-cup calorimeter. If the molar mass of the metal is 57.28 g/mol, and you measure that the reaction absorbed 163 J of heat, what is the enthalpy of this reaction in kJ per mole of limiting reactant?
Enter your answer numerically to three significant figures in units of kJ/mol.
a. 35.5
b. 36.2
c. 37.2
d. 34.3
35.5
35.5005 margin of error +/- 1%
You determine that the specific heat capacity of your unknown metal is 0.133 J/goC. What is the identity of the metal?
Enter your answer as an elemental symbol (ex: Li).
Refer to the CRC Handbook of Chemistry and Physics. Navigate to "Properties of the Elements & Inorganics" and select "Heat Capacity of the Elements at 25°C". If you open the interactive table, you can sort the table by any of the columns.
http://hbcponline.com/faces/contents/ContentsSearch.xhtml
a. Cl
b. O
c. Na
d. Pt
Pt
CuSO4 absorbs light strongly at a wavelength of 635 nm. Consider that you measure the initial intensity of light, I0 (Lzero), entering the solution at 635 nm, and the intensity of light passing through the solution, I, at 635 nm.
Sample 1: 0.400 M CuSO4
Sample 2: 0.200 M CuSO4
Which of the following statements is true?
a. The absorbance of light, A, will be higher for Sample 1 compared to Sample 2.
b. The absorbance of light, A, will be the same for Sample 1 compared to Sample 2.
c. The absorbance of light, A, will be lower for Sample 1 compared to Sample 2.
a. The absorbance of light, A, will be higher for Sample 1 compared to Sample 2.
The reported molar absorptivity of Red Dye #3 is 2.861 L mol-1 cm-1. If a solution of Red Dye #3 displays an absorbance of 0.98 in a cuvette that is 0.643 cm in length, what is the concentration of the dye in solution?
Report your response to three digits after the decimal. _____ M
a. 0.534
b. 0.533
c. 0.535
d. 0.540
0.533
The concentration of dye in Solution A is 22.896 M. You have 13 mL of water at your disposal to make the dilutions.
The solution is diluted twice, to make Solutions B and C.
In the first dilution, 3 parts of Solution A is diluted with 12 parts water to make Solution B.
In the second dilution, 8 parts of Solution B is diluted with 4 parts water to make Solution C.
What is the concentration of dye in Solution C?
Provide your response to three digits after the decimal.
a. 3.045
b. 3.053
c. 3.066
d. 3.032
3.053
A stock solution of Blue #1 has a concentration of 3.612 M. 2 mL of this solution is diluted with 9 mL water. What is the concentration of the resulting solution?
Provide your response to 3 significant figures.
a. 0.657
b. 0.544
c. 0.112
d. 0.953
0.657
A student's calibration curve for Blue #1 at 635 nm yields a straight line described by the equation y = 0.321 x + 0.015. If the measured absorbance for a solution of unknown concentration of Blue #1 is 0.31, what is the concentration of the Blue #1 solution?
Provide your response to three digits after the decimal.
a. 0.929
b. 0.329
c. 0.919
d. 0.939
0.919
A student measures the absorbance of a sample of red dye #3 using a spectrophotometer. If the absorbance is measured as 0.288, what is the concentration of red dye #3 in the sample?
Enter your answer in units of micromolar to three significant figures. d = 1.00 cm. For Red dye #3, ε = 7.96e4 M-1 cm-1.
a. 3.65
b. 3.62
c. 3.63
d. 3.64
3.62
A student makes three plots of their data and finds that a plot of [A] vs t is non-linear, a plot of ln[A] vs t is linear, and a plot of 1/[A] vs t is non-linear. What is the rate law of the reaction?
a. Rate = k
b. Rate = k[A]
c. Rate = k[A]2
d. Rate = k[A]3
b. Rate = k[A]
Which of the following sets of units could be appropriate for a zero-order rate constant?
a. s^-1
b. L mol^-1 s^-1
c. L^2 mol^-2 s^-1
d. L^3 mol^-3 s^-1
e. mol L^-1 s^-1
e. mol L^-1 s^-1
You will need to generate a set of graphs to answer this question.
Concentration vs time data for the following decomposition reaction was collected at 300 K. The data is shown in the table below.
What is the rate constant for the reaction at this temperature (in units of min-1)?
H2O2(aq) → H2O(l) + 1/2 O2(g)
0 min: 0.00866 [H2O2](mol/L)
500 min: 0.00305 [H2O2](mol/L)
1000 min: 0.00106 [H2O2](mol/L)
1500 min: 0.00037 [H2O2](mol/L)
2000 min: 0.00013 [H2O2](mol/L)
a. 0.0025
b. 0.0034
c. 0.0062
d. 0.0021
0.0021
What is the safety pictogram for household bleach (sodium hypochlorite solution, 5-12.5%)?
SDS: https://www.flinnsci.com/sds_736-sodium-hypochlorite-solution/sds_736/
a. irritant
b. skin corrosion/burns
c. explosive
d. aquatic toxicity
b. skin corrosion/burns
Which of the following is the correct formula for the precipitate formed when aqueous solutions of sodium carbonate and copper(II) sulfate are combined?
a. Na2SO4
b. CuCO3
c. Cu2(CO3)2
d. NaSO4
CuCO3
What is the term for a solution that is a good conductor of electricity?
a. aqueous electrolyte
b. nonelectrolyte
c. strong electrolyte
d. weak electrolyte
e. none of the above
c. strong electrolyte
Write a balanced net ionic equation for the reaction of aqueous solutions of cadmium(II) chloride and sodium sulfide.
a. CdCl2(aq) + Na2S(aq) ⟶ CdS (aq) + 2 NaCl(aq)
b. Cd^2+(aq) + 2 Cl^-(aq) + 2 Na+(aq) + S^2-(aq) ⟶ CdS(s) + 2 NaCl(aq)
c. Cd^2+(aq) + S^2-(aq) ⟶ CdS(s)
d. Cd^2+(aq) + 2 Cl^-(aq) + 2 Na^+(aq) + S^2-(aq) ⟶ CdS(s) + 2 Na^+(aq)
e. there is no reaction
c. Cd2+(aq) + S2-(aq) ⟶ CdS(s)
Write a complete, balanced equation for the reaction that occurs when sodium metal reacts with water to form hydrogen gas and aqueous sodium hydroxide.
a. Na(s) + 2H2O(l) → 2NaOH(aq) + 2H2(g)
b. Na(s) + 2H2O(l) → NaOH(aq) + 2H2(g)
c. Na(s) + H2O(l) → NaOH(aq) + H2(g)
d. Na(s) + H2O(l) → NaOH(aq) + H(g)
e. 2Na(s) + 2H2O(l) → 2NaOH(aq) + H2(g)
e. 2Na(s) + 2H2O(l) → 2NaOH(aq) + H2(g)
Green light has a wavelength of 5200 Å. Calculate the energy of one photon of green light.
a. 3.4 × 10-40 J
b. 3.4 × 10-30 J
c. 3.8 × 10-29 J
d. 3.4 × 10-27 J
e. 3.8 × 10-19 J
3.8 × 10-19 J
Consider that you prepared a solution by dissolving 1.52 mL of an unknown organic substance (d = 0.953 g/mL) into 25.2 mL of cyclohexane (d = 0.774 g/mL). What is the mass percent of the unknown in the solution?
a. 6.93
b. 6.91
c. 6.92
d. 6.94
6.91
6.913 margin of error +/- 1%
If you have an aqueous solution that is 17 % Na3PO4 by mass, what is the molality of Na3PO4 in the solution?
Enter your answer in units of molality to three significant figures.
a. 1.38
b. 1.64
c. 1.73
d. 1.25
1.25
1.2494 margin of error +/- 1%
What would be the freezing point of a solution that has a molality of 1.679 m which was prepared by dissolving biphenyl (C12H10) into naphthalene? Relevant information is provided below. Provide your response to three digits after the decimal.
solvent naphthalene (C10H8) freezing point: 80.6°C
solvent naphthalene (C10H8) Kf (°C/m): 6.9
solvent naphthalene (C10H8): boiling point (°C): 218°C
a. 83.217
b. 55.904
c. 73. 754
d. 69.015
69.015
69.0149 margin of error +/- 1%
Arrange the following aqueous solutions in order of increasing boiling point temperature (lowest to highest temperature, with 1 being the lowest and 4 being the highest):
1. 0.20 m glucose
2. 0.30 m BaCl2
3. 0.40 m NaCl
4. 0.50 m Na2SO4.
1
3
2
4
Consider that you prepared a solution by mixing 0.2 g solute with 9.32 g of solvent. If you measured that the solution had a molality of 0.138 m, what is the molar mass of the solute?
a. 156
b. 289
c. 453
d. 475
156
155.5016 margin of error +/- 1%
What is the molecular shape of NO2- as predicted by the VSEPR theory?
a. linear
b. trigonal planar
c. bent
d. tetrahedral
e. see-saw
bent
A sp3d hybridized central atom has what angles between its hybrid orbitals?
a. 120° only
b. 120° and 109.5°
c. 109.5° only
d. 120° and 90°
e. < 90°only
120° and 90°
Which of the following species has the largest dipole moment (i.e., is the most polar)?
a. H2
b. H2O
c. H2S
d. H2Se
e. CH4
H2O
What is the best Lewis structure for N2H4?
How many resonance structures are possible for NO3-?
a. 1
b. 2
c. 3
4. 4
3
An anhydrous (water removed) salt has a formula mass of 167.748 g/mol. If the hydrated version of the salt has 6 mol of water associated with it, what is the mass % of water in the hydrated salt?
Report your answer to three digits after the decimal.
a. 74.358
b. 63.906
c. 43.562
d. 39.187
39.187
Sam records the mass of his evaporating dish as 6.61 g.
He records the mass of the evaporating dish and the sample of hydrate as 16.791 g.
After heating the sample in the evaporating dish to constant weight, the mass of them combined is 11.715 g.
How many moles of water were removed from the sample by the heating process?
Report your answer with three digits after the decimal
a. 0.282
b. 0.292
c. 302
d. 312
0.282
Which of the following best describes the reaction, if any, that occurs when aqueous solutions of iron(III) nitrate and sodium iodide are combined?
a. double displacement
b. acid base (neutralization)
c. single displacement
d. redox
e. no reaction
d. redox
When some of the sugar added to iced tea remains undissolved at the bottom of the glass, the solution is
a. dilute
b. saturated
c. unsaturated
d. polar
e. nonpolar
b. saturated
The AM station KPUE plays your favorite music from the 20's and 30's at 1290 kHz. Find the wavelength of these waves.
enter a whole number to complete the expression: ____ m
a. 245
b. 233
c. 284
d. 294
233
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