NYU GEN CHEM 2 LAB FINAL
44.57 mL of a 3.00 M solution is transferred to a 100-mL volumetric flask. The flask is filled with deionized water to the graduation line. The concentration of the dilution is ____M. keep your answer with three significant figures.
1.34 M Dilution calculation convert M to moles of solution (MxL) divide moles by VTotal (In L)
0.983 grams of a unknown compound (nonelectrolyte) is dissolved in 9.88 grams of water (Kf = 1.853 0C/m). The solution freezes at -1.6 0C. The molar mass of the unknown compound is ________. keep your answer with three decimal places.
115.226 g/mol calculate kg of water calculate deltaTf deltaTf/-Kf=m m x kg of water = moles given grams/moles -) molar mass
The rate constant k for a reaction is 2.667E-8 M-1s-1 when the reaction proceeds at 25 °C. If the activation energy is 71.887 kJ/mol, the rate constant at 35 °C is ____ M-1s-1 . keep your answer in a scientific notation and two significant figures.
6.8E-8 M-1s-1 lnK2-lnK1 = -Ea/R (1/T2 - 1/T1)
Which of the following statements is true? A. Determining the end point of the titration with our naked eyes is a significant source of error in this lab B. The solutions we are dealing with in the experiment are ideal solutions. C. Plotting Ksp vs. [Pb2+] gives a linear graph
A. Determining the end point of the titration with our naked eyes is a significant source of error in this lab
Which of the following is the correct equilibrium constant expression for the dissolution of NH4Cl equilibrium? A. K = [NH4+][Cl-] B. K= [NH4Cl] / [NH4+][Cl-] C. K= [NH4+][Cl-]/ [NH4Cl] D. K= 1/[NH4+][Cl-]
A. K = [NH4+][Cl-]
Which of the following is the correct equilibrium constant expression for this reaction? HBB(aq) + H2O(l) « BB-(aq) + H3O+(aq) A. K=[BB-][H3O+] / [HBB] B. K=[BB-][H3O+] / [HBB][H2O] C. K=[HBB] / [BB-][H3O+] D. K=[HBB][H2O] / [BB-][H3O+]
A. K=[BB-][H3O+] / [HBB]
The hydronium ion concentration in a solution that has a pH of 2.67 will be___ M.
.0021 M 10^-pH = [H+]
The following volumes of solution are combined in a test tube: 0.77 mL of 0.20 M potassium iodide 0.50 mL of 1% starch 0.61 mL of 0.20 M ammonium persulfate 0.50 mL of 0.012 M sodium thiosulfate 1.23 mL of 0.20 M potassium nitrate 1.39 mL of 0.20 M ammonium sulfate The concentration of iodide in the solution in the test tube is ______. keep your answer with three decimal places.
.0308 -) .031 (3 decimal places) go from moles of KI to moles of I add up volumes (L) divide moles of I by total V (in L)
0.0100 M KI aqueous solution is used to titrate 10.00 mL 0.09 M Pb(NO3)2 solution, at the end point, 6.81 mL KI solution is consumed. The equilibrium concentration of Pb2+ ions is _______ M. Please keep your answer with three significant figures.
.0535M M1V1=M2V2
The transmittance of the sample was 85.32% determined by the colorimeter with the path length of the light through the solution was exactly 1 cm. Calculate the Absorbance for the species _______. keep your answer with 3 significant figures.
.0689 A= 2.000-log(%T)
The bromothymol blue solution has a pH of 7.64, the ratio of [BB-]/[HBB] derived from the spectrophotometric data is 0.49. The Ka value of this solution will be ___.
1.1E-8 10^-pH= [H+] [H+](.49) = Ka
The following data are obtained by performing the iodine-clock experiment: determination 1 2 3 4 trial 1 time (s) 262 142 111 83 trial 2 time (s) 260 144 121 78 trial 3 time (s) 272 138 116 80 As indicated in the lab manual, this is the time it took to raise the concentration of I2 from 0 to 6.0 x 10-4 M. The rate for determination 1 is _______. Please use the scientific notation for your answer, and keep your answer with two significant figures.
2.3E-6 M/s rate = M/s -find the average time for determination one -divide molarity by average time
The pKa for an acid with Ka = 0.00033 will be ____ . Answer Key: ____
3.48 -logKa=pKa
We know that pure benzene freezes at +5.51 °C. A 2.46 m solution of a non-volatile nonelectrolyte dissolved in benzene is observed to freeze at -5.18 °C. Then the molal freezing point depression constant (Kf) for benzene will be ______. keep your answer with 3 decimal places.
4.346 deltaTf= Tfsol-Tfpure Kf=deltaTf/m
1.0 L buffer was made with 87.71 mL of 0.15 M acetic acid (Ka=1.8 x 10-5) and 177.88 mL of 0.25 M acetate. After 1.00 mL of 1.0 M HCL is added to the buffer, the pH will be _____.
5.23 -convert acetic acid and acetate to moles and perform dilution to get concentrations (moles/Vt (1L)) -plug values into Henderson Hasselbach Equation ph=pKa+log([A-]/[HA]) -however, subtract concentration of acid (determined via ((MxL)/Lt)) from concentration of base part, and add concentration of acid to acid part and then solve as you would ph=pKa+log([A-]-[acid]/[HA]+[acid])
1.0 L buffer was made with 86.36 mL of 0.15 M acetic acid (Ka=1.8 x 10-5) and 177.05 mL of 0.25 M acetate, the pH of this buffer will be _____ .
5.28 -convert acetic acid and acetate to moles and perform dilution to get concentrations (moles/Vt (1L)) -plug values into Henderson Hasselbach Equation ph=pKa+log([A-]/[HA])
In this experiment, if the plot of lnk vs 1/T has a slope of -6829 K. The activation energy, Ea will be _____ kJ/mol. keep your answer with three significant figures.
56.8 kJ/mol Ea=-slope(R)
The solubility product constant (Ksp) of a low solubility salt, AB is 3.6 x 10-9. The molar solubility of AB in water will be _______ mol/L.
6E-5 Ksp=[A][B] Ksp=x^2 x= molar solubility
In this experiment, we will be performing a titration with a buret. Place the steps in order. 1. Record the pH when 0.0 mL of NaOH has been added to your beaker containing 25 mL of HCl and 25 mL of deionized water. 2. Record the pH of your partially neutralized HCl solution when 5.00 mL of NaOH has been added from the buret. 3. Record the pH of your partially neutralized HCl solution when 10.00 mL, 15.00 mL and 20.00 mL of NaOH has been added. 4. Record the pH of your partially neutralized HCl solution when 21.00 mL, 22.00 mL, 23.00 mL and 24.00 mL of NaOH has been added. 5. Add NaOH one drop at a time until a pH of 7.00 has been reached, then record the volume of NaOH added from the buret. 6. Record the pH of your basic HCl-NaOH solution when 26.00 mL, 27.00 mL, 28.00 mL, 29.00 mL and 30.00 mL of NaOH has been added. 7. Record the pH of your basic HCl-NaOH solution when 35.00 mL, 40.00 mL, 45.00 mL and 50.00 mL of NaOH has been added from your 50 mL buret. A. 1,2,3,4,5,6,7 B. 1,2,3,7,6,5,4 C. 1,3,5,7,2,4,6 D. 7,6,5,4,3,2,1
A. 1,2,3,4,5,6,7
To determine the rate law of the reaction, 2A + 2B ® C + D, the following experiment data are obtained. Trial 1 2 3 4 5 Initial [A] M 1.10 x 10-2 2.20 x 10-2 1.10 x 10-2 3.30 x 10-2 1.10 x 10-2 Initial [B] M 1.30 x 10-2 1.30 x 10-2 2.60 x 10-2 1.30 x 10-2 3.90 x 10-2 Initial rate, M/s 3.20 x 10-3 6.40 x 10-3 12.8 x 10-3 9.60 x 10-3 28.8 x 10-3 what is the average rate constant? A. 1.7214 x 103 M-2S-1 B. 1.7214 x 103 M-1S-1 C. 1.7214 x 10-3 M-2S-1 D. 1.7214 M-2S-1
A. 1.7214 x 103 M-2S-1 Third order = M-2S-1
What is the balanced net ionic equation for the chromate/dichromate equilibrium we will be studying in this experiment? A. 2H3O+(aq) + 2CrO4-2(aq) « Cr2O7-2(aq) + 3H2O(l) B. 2H3O+(aq) + 2K2CrO4(aq) « Cr2O7-2(aq) + 3H2O(l) C. 2CrO4-2(aq) « Cr2O7-2(aq) D. CrO4-2(aq) « Cr2O7-2(aq)
A. 2H3O+(aq) + 2CrO4-2(aq) « Cr2O7-2(aq) + 3H2O(l)
To determine the rate law of the reaction, 2A + 2B ® C + D, the following experiment data are obtained. Trial 1 2 3 4 5 Initial [A] M 1.10 x 10-2 2.20 x 10-2 1.10 x 10-2 3.30 x 10-2 1.10 x 10-2 Initial [B] M 1.30 x 10-2 1.30 x 10-2 2.60 x 10-2 1.30 x 10-2 3.90 x 10-2 Initial rate, M/s 3.20 x 10-3 6.40 x 10-3 12.8 x 10-3 9.60 x 10-3 28.8 x 10-3 what is the overall reaction order? A. 3 B. 1 C. 4 D. 2
A. 3
How do we recognize the endpoint of each of the titrations in this experiment? A. A yellow precipitate persists in the solution for 30 seconds. B. The computer and interface will show a rapid rise in pH. C. The solution turns pink. D. When all PbI2 dissolves.
A. A yellow precipitate persists in the solution for 30 seconds.
Which species is being oxidized in the following redox reaction? 2Fe2+(aq) + Cl2(g) → 2Fe3+(aq) + 2Cl-(aq) A. Fe2+(aq) B. Fe3+(aq) C. Cl2(g) D. Cl-(aq)
A. Fe2+(aq)
Which of the following statement of a solution with pH of 8.0 is true? A. It is ten times less acidic than a pH of 7.0 B. It is half as acidic as a solution with a pH of 4.0 C. It is twice as acidic as a solution with a pH of 4.0 D. It is ten times more acidic than a pH of 7.0
A. It is ten times less acidic than a pH of 7.0
The rate law of the reaction (2A + B + C ® D + E) is rate = k[A][B]. What will be the unit for the rate constant, k? A. M-1S-1 B. M-2S-1 C. M-3S-1 D. M-1/2S-1
A. M-1S-1 second order = M-1S-1
Why do we vary the Pb2+ concentration between our titrations in this experiment? A. This is an effort to get a series of dilutions and then extrapolate the data to determine the Ksp at an infinitely dilute solution. B. We can obtain data with more trials. C. To guarantee the determined Ksp value is accurate for all diluted solutions. D. none of the aboves
A. This is an effort to get a series of dilutions and then extrapolate the data to determine the Ksp at an infinitely dilute solution.
What is the goal of this experiment? A. To determine the Ksp of PbI2 B. To learn to handle lead containing toxic compounds C. To understand the limitations of our theoretical plotting method D. to learn how to use a buret
A. To determine the Ksp of PbI2
How should you report your reading from the buret? A. To the nearest calibration mark, then add one estimated digit B. To four significant figures C. To the nearest calibration mark D. To the nearest tenth of a mL E. To the nearest mL F. To three significant figures
A. To the nearest calibration mark, then add one estimated digit
How should you report your reading from the buret? A. To the nearest calibration mark, then add one estimated digit B. To the nearest mL C. To the nearest calibration mark D. To the nearest tenth of a mL E. To four significant figures F. To three significant figures
A. To the nearest calibration mark, then add one estimated digit
According to the procedure in the lab manual, which of the following graph in our experiment will display a linear relationship? A. Volume vs. 1/Pressure B. Temperature vs. Time C. Volume vs. Pressure D. pH vs. Time E. pH vs. Volume NaOH added F. Temperature vs. Volume
A. Volume vs. 1/Pressure
Which is the reduction half-reaction in this spontaneous reaction? 2Al(s) + 3Zn2+(aq) → 2Al3+(aq) + 3Zn(s) A. Zn2+(aq) + 2e- → Zn(s) B. Al(s) → Al3+(aq) + 3e- C. Al3+(aq) + 3e- → Al(s) D. Zn(s) → Zn2+(aq) + 2e-
A. Zn2+(aq) + 2e- → Zn(s)
What causes deviations from the solution ideality? A. the interactions between solute and solute particles B. the interactions between solute and solvent particles C. the interactions between solvent and solvent particles D. none of the aboves
A. the interactions between solute and solute particles
Calculate the standard cell potential for the reaction observed when an aluminum strip were placed in a zinc solution? Please refer to the Appendix IV.4 in the lab manual for the standard reduction potentials. A. 1.04 V B. 0.90 V C. 2.42 V D. 3.46 V
B. 0.90 V
Which of the following statements concerning the saturated solution of A2B3 is true? A. [A]=3[B] B. 3[A]=2[B] C. 2[A]=3[B] D. [A]=[B]
B. 3[A]=2[B]
An electrochemical cell is constructed using two half-cells: Ni(s) in Ni(NO3)2(aq) and Cu(s) in Cu(NO3)2(aq). The two half cells are connected by a NaNO3 salt bridge and two copper wires from the electrodes to a voltmeter. Based on their respective standard reduction potentials in Appendix IV.4 in the manual, which half-cell is the cathode for this spontaneous reaction? A. The nickel half-cell B. The copper half-cell
B. The copper half-cell
What is the concentration of the NaOH we will be using in the Aspirin Experiment? A. 0.01 M B. 2.0 M C. 1.0 M D. 0.1 M
C. 1.0 M
How many moles of electrons are transferred per mole of the reaction? 2Al(s) + 3Zn2+(aq) → 2Al3+(aq) + 3Zn(s) A. 2 B. 3 C. 6 D. 1
C. 6
To prepare a buffer with a pH of 4.25, which of the following weak acids would be the best candidate ? A. Propionic Acid (Ka= 1.3x10-5) B. Formic Acid (Ka= 1.8x10-4) C. Benzoic Acid (Ka= 6.5x10-5) D. Acetic acid (Ka= 1.8x10-5)
C. Benzoic Acid (Ka= 6.5x10-5) Best acid would be when pKa=pH (or is as close as possible) pKa=-log(Ka)
All the following compounds have the same Ksp, which one is the most soluble? A. C2D B. CD3 C. C2D3 D. CD
C. C2D3 With same Ksp, most ions will be most soluble
Which species is acting as the oxidizing agent in the following redox reaction? 2Fe2+(aq) + Cl2(g) → 2Fe3+(aq) + 2Cl-(aq) A. Cl-(aq) B. Fe3+(aq) C. Cl2(g) D. Fe2+(aq)
C. Cl2(g)
If the ratio between the basic component and the acidic component , [base]/[acid], in a buffer is higher than one. It means: A. the buffer has a higher capacity towards bases B. the buffer has the same capacity towards both acids and bases C. the buffer has a higher capacity towards acids
C. the buffer has a higher capacity towards acids
How many significant figures of a pH value of 1.78? A. 3 B. 1 C. 4 D. 2
D. 2
The number of graphs you need to generate and turn in at the end of the lab? A. 7 B. 4 C. 0 D. 8 E. 6 F. 5
D. 8
What approximation is the Henderson-Hasselbach equation based on? A. The equilibrium concentrations of the basic and acidic components in a buffer will be very close to their initial concentrations B. The common ion effect inhibits dissociation of the weak acid C. The buffer has the same capacity towards acid and base D. A and B E. none of the above
D. A and B
What would you observe if you place a zinc strip in a chromium(III) solution? (hint: you will need the data in the Appendix IV.4 in the lab manual to answer this question) A. Zinc strip will dissolve B. Chromium metal will plate out on the zinc strip C. no reaction D. A and B
D. A and B
Why do we need to add potassium nitrate (KNO3) and ammonium sulfate ((NH4)2SO4) solutions to the reaction mixture in this experiment? A. To maintain the total volume of the reaction mixture constant while we vary the concentration of one reactant and keep the concentration of the other reactants the same. B. to keep the reaction rate constant C. To keep the ionic strength constant. D. A and C
D. A and C
Why does the freezing point of a solution decrease while the solution is further cooling down? A. This is because as the solution freezes, the concentration increases, which reduces the freezing point further. B. This is because as the solution freezes, the solute is frozen out of the solution. C. This is because as the solution freezes, some of the solvent is frozen out of the solution, the concentration increase. D. A and C
D. A and C
Which of the following statement of a buffer is true? A. A buffer is a solution resist changes in pH when some small amount of either acid or base is added. B. A buffer solution consists of weak acid and its conjugate base. C. An ideal buffer will have a roughly equal concentration of the conjugate acid and base pair in the buffer. D. All of the above
D. All of the above
Which of the following statements is true? A. The average rate of a reaction over a period of time can be expressed by dividing the concentration change of any reactant or product by the elapsed time. B. The initial rate is an average rate at the beginning of the reaction. C. The initial rate is the minimum of the rate of a reaction. D. An instantaneous rate is the rate at some instant moment of the reaction.
D. An instantaneous rate is the rate at some instant moment of the reaction.
Accuracy is a measure of: A. The random errors that the student made during the measurement. B. How close a series of experiment measurements are to each other. C. The quality of the instrument used to do the measurement. D. How close any measurement is to the actual value.
D. How close any measurement is to the actual value.
Explain the term parallax in the context of reading a meniscus and how you would avoid any error that might be introduced by parallax? A. Parallax error is the apparent displacement of an object as seen from two different viewpoints that are not in line with the object. The meniscus must be read consistently from the top of the graduated cylinder. B. Parallax provides the depth perception necessary for our measurement. The meniscus must be read consistently at arm's length. C. Parallax provides the depth perception necessary for our measurement. The meniscus must be read consistently from the top of the graduated cylinder. D. Parallax error is the apparent displacement of an object as seen from two different viewpoints that are not in line with the object. The meniscus must be read consistently at eye level.
D. Parallax error is the apparent displacement of an object as seen from two different viewpoints that are not in line with the object. The meniscus must be read consistently at eye level.
How would you determine the number of significant figures when reading the volume of an aqueous solution in a graduated cylinder? A. Read the bottom of the meniscus at eye level, and round to the nearest tenth of a mL. B. Read the bottom of the meniscus at eye level, and round to the nearest calibration mark on your instrument. C. Read the top of the meniscus and round to the nearest calibration mark. D. Read the bottom of the meniscus at eye level; report your data to the nearest calibration mark and add an estimated digit.
D. Read the bottom of the meniscus at eye level; report your data to the nearest calibration mark and add an estimated digit.
Which of the following item will NOT be used in this experiment? A. Buret B. Lab Quest © Interface C. pH Probe D. Volumetric Flask E. Temperature Probe
D. Volumetric Flask
Which species is produced at the anode for the following redox reaction? Zn(s) + Cu2+(aq) → Zn2+(aq) + Cu(s) A. Cu(s) B. Cu2+(aq) C. Zn(s) D. Zn2+(aq)
D. Zn2+(aq)
We need 1.00 L of an acetic acid/acetate (Ka = 1.80 x 10-5) buffer with a starting pH of 4.500. 500.0 mL of the buffer must be able to resist the addition of 20.00 mL of 0.500 M NaOH while remaining below pH 5.250. How many mL of 1.00 M stock acid solution must be used in preparation of this buffer? A. 32.0 mL B. 36.3 mL C. 25.0 mL D. 18.2 mL E. 50.1 mL
E. 50.1 mL
Which of the following statements is true? A. At low pH, HBB solution appears yellow and absorbs most light in the blue-violet region. B. At low pH, HBB solution appears blue and absorbs most light in the blue-violet region. C. At high pH, BB- solution appears yellow and absorbs most light in the blue-violet region. D. At high pH, BB- solution appears blue and absorbs most light in the orange region. E. A and D F. B and C G. none of the above
E. A and D
What should be included in a properly labeled graph? A. A title B. Labeled Axes C. You and your partner's names D. Your lab bench number E. All of the above
E. All of the above
The main components of a SpectroVis® Plus Spectrophotometer are A. a photovoltaic cell B. a tungsten bulb C. a diffraction grating D. a linear CCD array detector E. B, C and D F. All of the above
E. B, C and D
What are the precautions we need to take when handling sodium hydroxide in this Lab? A. Avoid skin contact B. Avoid inhalation C. Tie back long hair D. Wear appropriate lab attire E. Wear approved splash-proof goggles at all times F. All of the above G. A and B H. only A-D but not E and F
F. All of the above
D. All of the above
In part II of this experiment, we will construct several electrochemical cells for several spontaneous reactions. Why do we get a similar cell potential value but not the same to the calculated values? A. The cells we construct in lab will not be exactly at 25oC and 1.0 M concentration. B. The cells we construct have an internal resistance. C. The voltmeters we use will draw some current. D. All of the above
B. chlorine can oxidize iodide ions
It was found that chlorine can oxidize silver metal to silver ions, and that silver ions can oxidize iodide ions to iodine, then which one of the following statement is true? A. chlorine can reduce iodide ions B. chlorine can oxidize iodide ions C. iodide can reduce silver D. iodide can oxidize silver ions
The outside of the cuvets should be dried with a Kimwipe before placing it in the chamber of the spectrophotometer. True False
True
The potentials of the half-reactions is an intensive property and do not depend on the amount of substance present. True False
True
You must complete the buffer calculation on data sheet I prior to entering lab. True False
True
According to the Arrhenius equation, a reaction with a large value of Ea will have a smaller rate constant, k, thus the reaction is slow. True False
True Large Ea = slow reaction = smaller k
A stock solution, 0.201 M was used to make a dilution by mixing 4.18 mL of stock solution with 45.82 mL of deionized water. The concentration of the diluted solution is _______. Please express your answer in scientific notation and keep your answer with three significant figures.
.0168 M M1V1=M2V2
A solution of [Cu(H2O)6]+2 was made by dissolving 1.236 g of pure copper wire (MM= 63.546g/mol) in a concentrated HNO3 solution and diluted to 1.00x102 mL. The concentration of the solution is _______. Keep your answer with three significant figures.
.195 Dilution: g-) moles, moles/liters= molarity
The molality of the ions in a solution made from dissolving 14.3 g of CaCl2 (MM=110.98 g/mol) in 195 mL of water is _____. keep your answer with three decimal places. (Density of water @ 25 °C is 0.9982 g/mL).
.662 calc. moles of CaCl2 calc. kg of water (mL x g/mL = g, g/1000= kg) moles of CaCl2/kg of water
The pure water freezes at 0.0 °C. An aqueous solution contains nonelectrolyte glucose freeze at -1.74 °C. The molality of the glucose solution is _______. The molal freezing point depression constant (Kf) for water is 1.853 °C/m. keep your answer with three decimal places.
.939 deltaTf= Tf(sol) - Tf(pure) m= deltaTf/-Kf
The hydroxide ion (OH-) concentration in an aqueous solution is 3.3E-12 M at 25℃. Calculate the pH: ________ (Kw = 1.000 x 10-14 keep your answer with 3 decimal places.)
2.519
What is the balanced net ionic equation for the acetic acid/acetate equilibrium we will be studying in this experiment? A. CH3COOH (aq) +H2O(l) « CH3COO-(aq) + H3O+(aq) B. CH3COOH (aq) +H3O+(l) « CH3COO-(aq) + H2O(l) C. 2CH3COOH (aq) « 2CH3COO-(aq) + 2H+(aq) D. CH3COOH (aq) « CH3COO-(aq)
A. CH3COOH (aq) +H2O(l) « CH3COO-(aq) + H3O+(aq)
Which of the following statements about the activation energy, Ea, of a reaction is false ? A. The activation energy decreases when temperature increases. B. It is an energy "price tag" that the reactants have to pay in order to react. C. It is the energy barrier that the reactants have to overcome in order to undergo a reaction. D. It is the minimum energy that the reactants must have in order to react.
A. The activation energy decreases when temperature increases.
What happens when we add sodium hydroxide to acetylsalicylic acid? A. The hydrolysis reaction is accelerated. B. To prevent unwanted side reactions that could interfere optically or change the Stoichiometry of the reaction. C. The hydrolysis process is decelerated and slowed down. D. We shift the equilibrium of the reaction to favor the reactants.
A. The hydrolysis reaction is accelerated.
The rate law for reaction( aA + bB ® cC + dD ) is: rate = k[A]x[B]y. Which one of following statements is not true? A. The reactants orders are directly related to the stoichiometric coefficients, a and b. B. k is the rate constant, which can be determined by experiments. C. The reactant orders can be positive, negative, zero or even fractions. D. The reaction rate depends primarily on the concentration of reactants and the temperature.
A. The reactants orders are directly related to the stoichiometric coefficients, a and b.
We have two solutions A and B. Solution A is prepared by dissolving 5 g of glucose (C6H12O6) in 50.0 mL water while solution B is prepared by dissolving 5 g of CaCl2 in 50.0 mL water. Which solution would you expect to have the lowest freezing point? A. The solution B. B. The solution A. C. The two solutions have the same freezing point.
A. The solution B. Solution A: i=1 Solution B: i=3 I=3 will have a greater effect and lower the fp more
The clock reaction is used in this experiment to study the reaction kinetics. What is the role of starch in the reaction mixture? A. The starch is added to the reaction mixture as an indicator for I2. The reaction solution will turn from colorless to dark blue when a certain amount of I2 is produced. B. The starch is added to increase the concentration of the reaction mixture. C. The starch is added to maintain the total volume of the reaction mixture. D. The starch is added to the reaction mixture as an indicator for I2. The reaction solution will turn from dark blue to colorless when a certain amount of I2 is produced.
A. The starch is added to the reaction mixture as an indicator for I2. The reaction solution will turn from colorless to dark blue when a certain amount of I2 is produced.
What is the role of the FeCl3-KCl-HCl solution in the experiment? A. To complex with salicylic acid to form a violet complex. B. To accelerate the rate at which acetylsalicylic acid hydrolyzes to become salicylate dianion and acetate ion. C. To convert salicylic acid to salicylate dianion D. To accelerate the rate at which salicylic acid and acetic anhydride react to form acetylsalicylic acid and acetic acid.
A. To complex with salicylic acid to form a violet complex.
What is Kb? A. a constant proportional to the boiling point elevation. B. a constant depends on the identity of the solute. C. a constant has a unit of oC/M D. a constant proportional to the freezing point depression.
A. a constant proportional to the boiling point elevation.
What do we use for the cooling in order to determine the freezing point in this experiment? A. an ice-salt-water slurry B. ice-water slurry C. a freezer D. none of the above
A. an ice-salt-water slurry
The following gaseous reaction reaches equilibrium: PCl3(g) + Cl2(g) « PCl5(g). What happens to the amount of Cl2 (g) if more PCl3 (g) is added? A. decrease B. no change C. increase
A. decrease
The following exothermic reaction reaches equilibrium: Ni+2 (aq) + SO2(g) + 2H2O(l) « Ni(s) + SO4-2(aq) + 4H+(aq) What happens to the amount of solid nickel if sodium hydroxide is added? A. increase B. decrease C. no change
A. increase
How does doubling the volume of the reaction vessel affect the yield of carbon dioxide? CaCO3(s) « CaO(s) + CO2(g) A. increase B. decrease C. no change
A. increase increase the volume, decrease the pressure, reaction will shift to the right to produce more moles of carbon dioxide.
In this experiment, which one of the following plots are we going to generate? A. lnk vs 1 over straight T B. k vs 1 over straight T C. lnk vs Ea D. Ea vs 1 over straight T
A. lnk vs 1/T
Consider the following exothermic equilibrium in a sealed vessel: 2HNO3(aq) + K2SO3 (aq) « SO2(g) + H2O(l) + 2KNO3(aq) What happens to the equilibrium reaction if gaseous argon is added to the vessel at constant volume? A. no change to the reaction. B. Reaction shifts to the right. C. Reaction shifts to the left.
A. no change to the reaction.
The goal of this experiment is A. to determine the rate law of the reaction of iodide with persulfate. B. to determine the reaction rate of the reaction of iodide with perfulfate. C. to determine the rate constant of the reaction of iodide with perfulfate. D. to determine the reaction mechanism of the reaction of iodide with perfulfate.
A. to determine the rate law of the reaction of iodide with persulfate.
Is there any difference when you compare the cooling curves of a pure liquid solvent and the one for a typical solution (see Figure 5.1 and Figure 5.2 on your lab manual)? A. yes, freezing of the pure solvent occurs at a constant temperature until all of the liquid has been frozen while a solution will not freeze at a constant temperature. B. Yes, the decreasing of solid temperature only occurs to the pure liquid solvent. C. no, both curves exhibit super cooling phenomenon. D. yes, only pure liquid solvent exhibits super cooling phenomenon.
A. yes, freezing of the pure solvent occurs at a constant temperature until all of the liquid has been frozen while a solution will not freeze at a constant temperature. Pure solvent freezes at constant temperature where the solution does not
When a chemical reaction reaches equilibrium, A. the forward and reverse reactions have stopped. B. the concentrations (or pressures) of the reactants are equal to the concentrations (or pressures) of the products. C. the concentrations (or pressures) of the reactants and products have reached constant values. D. the limiting reactant has been used up.
C. the concentrations (or pressures) of the reactants and products have reached constant values.
What is the volume measured by this 10 mL graduate cylinder? Image result for reading from a graduated cylinder A. 2.7 B. 2.68 mL C. 2.6 mL D. 2.56 mL
B. 2.68 mL
At how many different temperature are we going to run the iodine clock reactions in this experiment? A. 3 B. 5 C. 4 D. 6
B. 5 room temperature, 20oC below, 10oC below, 20oC above and 10oC above.
The following data is obtained to determine the activation energy, Ea as described in part I of this experiment. Please use LoggerPro to make lnk vs 1 over straight T plot and determine Ea. What will be the Ea value? k(M-1s-1) T(oC) 3.49×10-4 25 7.99×10-4 35 1.73×10-3 45 3.59×10-3 55 A. 85.4 kJ/mol B. 63.2 kJ/mol C. 7.60 x 103 kJ/mol D. 1.1x10-4 kJ/mol
B. 63.2 kJ/mol Ea= -slope(R) Slope = -7599 Ea= 7599(8.3145) -) gives J/mol Convert to kJ/mol
Which of the following statements about reaction mechanism is false? A. The rate of a reaction will depend upon the slowest elementary step in a reaction mechanism. B. All intermediates are short-lived and can not be isolated, so we can not prove a mechanism right or wrong. C. The molecularity is the number of reactant molecules shown in an elementary step. D. A reaction mechanism consists of a series of elementary steps to convert the reactants to the products.
B. All intermediates are short-lived and can not be isolated, so we can not prove a mechanism right or wrong.
What is the solubility product constant? A. It is the reaction quotient for an ionic salt in water. B. An equilibrium constant for the solubility equilibria. C. The product of a solubility experiment D. The criteria for dissolution of an ionic solid
B. An equilibrium constant for the solubility equilibria.
Which one of the following is not a colligative property? A. Freezing point depression B. Boiling point depression C. Vapor pressure lowering D. Osmotic pressure
B. Boiling point depression it is "boiling point elevation" NOT "boiling point depression"
Why do we set the colorimeter to 565 nm? A. It is the closest to the peak wavelength of the green light transmitted by the species B. It is the closest to the peak wavelength of the green light that is absorbed by the species C. It is the closest to the peak wavelength of the purple light that is absorbed by the species D. It is the closest to the peak wavelength of the purple light transmitted by the species
B. It is the closest to the peak wavelength of the green light that is absorbed by the species
Which of the following is the list of the metal cations will be tested in this experiment for the catalytic effects? A. Mg2+, Ca2+ and Al3+ B. Mg2+, Cu2+ and Fe2+ C. Mg2+, Ca2+ and Fe2+ D. Mg2+, Cu2+ and Fe3+
B. Mg2+, Cu2+ and Fe2+
In this lab, we run our experiments at a fixed wavelength, 565 nm. The color intensity of the solution is directly proportional to: A. The molar absorptivity of the solution B. The concentration of salicylic acid in the solution C. The concentration of FeCl3-KCl-HCl in the solution D. The concentration of acetylsalicylic acid in the solution
B. The concentration of salicylic acid in the solution
What is the main reason that a reaction rate increases by increasing temperature? A. The reactant particles will move faster and collide more often with an increasing temperature. B. The kinetic energy of the reactant particles increases, more reactant particles will have enough energy to overcome the energy barrier, activation energy (Ea), to react. C. The activation energy decreases while temperature increases, so the reaction rate increases. D. The reaction constant increases as temperature increases, so the reaction rate increases.
B. The kinetic energy of the reactant particles increases, more reactant particles will have enough energy to overcome the energy barrier, activation energy (Ea), to react.
What is the balanced net ionic equation for the complex ions of Cobalt(II) equilibrium we will be studying in this experiment? A. [Co(H2O)6]+2(aq) + 4Cl-(aq) « [CoCl4]-2(aq) B. [Co(H2O)6]+2(aq) + 4Cl-(aq) « [CoCl4]-2(aq) + 6H2O(l) C. [Co(H2O)6]+2(aq) « [CoCl4]-2(aq) D. [Co(H2O)6]+2(aq) « [CoCl4]-2(aq) + 6H2O(l)
B. [Co(H2O)6]+2(aq) + 4Cl-(aq) « [CoCl4]-2(aq) + 6H2O(l)
The van't Hoff coefficient, i is A. zero for an nonelectrolyte solution B. the number of ions formed when an electrolyte dissociates in water. C. a constant specific to the solvent. D. a factor logarithmically related to the boiling point elevation.
B. the number of ions formed when an electrolyte dissociates in water.
The solubility product constant will change when A. a common ion is added to the solution. B. the temperature is changed. C. more ions are added to the solution. D. add more solvent to the solution.
B. the temperature is changed.
What is the balanced net ionic equation for the dissolution of NH4Cl equilibrium we will be studying in this experiment? A. NH4Cl(s) « NH3+(aq) + Cl-(aq) + H+(aq) B. NH4Cl(aq) « NH3-(aq) + Cl-(aq) +2H+(aq) C. NH4Cl(aq) « NH4+(aq) + Cl-(aq) D. NH4Cl(s) « NH4+(aq) + Cl-(aq)
D. NH4Cl(s) « NH4+(aq) + Cl-(aq)
What concentration of hydrochloric acid will we be using in this lab? A. 2.0 M B. 1.0 M C. 0.2 M D. 0.02 M E. 0.01 M F. None of the above, we aren't using hydrochloric acid
C. 0.2 M
The stock solution (0.201 M) was used to make the dilutions below, whose % transmittances were used to prepare a Beer's Law calibration curve. The composition of individual solutions and % transmittances are given below. The path length, b, of the light through the solution was exactly 1cm. Volume Stock Cu(II) Solution, mL Volume of deionized water, mL %T 1.000 49.00 89.82 3.000 47.00 77.15 5.000 45.00 60.25 10.00 40.00 35.83 12.00 38.00 29.32 15.00 35.00 21.35 20.00 30.00 15.55 Using the above information, prepare a properly labeled Beer's Law plot (A vs concentration) using your LoggerPro© software. Perform a linear fit for the data. Print out your graph showing the linear fit, you will turn this in to your lab instructor when you come to lab. Make sure the graph has properly labeled axes, a title, and includes your name, lab locker #, and date. Using the Beer's Law plot you generated: determine the molar absorptivity for this species: A. 10.34 cm-1 M-1 B. 0.09518 cm-1 M-1 C. 10.43 cm-1 M-1 D. 0.09665 cm-1 M-1
C. 10.43 cm-1 M-1 slope (b)/path length (when given graph of A vs. Concentration)
We need to clean the volumetric glassware before making a measurement in lab. please place the steps in order: 1.Rinse with deionized water from your wash bottle. 2.Rinse with tap water. 3. rinse once (or preferably twice) with the solution you are going to be measuring. 4.Dispose of these rinses in your waste beaker. A. 2, 3, 1, 4 B. 2, 1, 4, 3 C. 2, 1, 3, 4 D. 1, 2, 3, 4
C. 2, 1, 3, 4
Accuracy is a measure of: A. How close a series of experiment measurements are to each other. B. The random errors that the student made during the measurement. C. How close any measurement is to the actual value. D. The quality of the instrument used to do the measurement.
C. How close any measurement is to the actual value.
Which of the following statements is true? A. The units of K depend on the coefficients in the balanced equation. B. K is unitless because the units always cancel out. C. K is unitless because the pressures or molarities in the equilibrium constant expression are unitless activities. D. The equilibrium constant, K, has units of mol/L.
C. K is unitless because the pressures or molarities in the equilibrium constant expression are unitless activities.
The following exothermic reaction reaches equilibrium in a sealed vessel: 3H2(g) + N2(g) « 2NH3(g) How does an increase in temperature affect the equilibrium? A. Reaction shifts to the right. B. No change to the reaction. C. Reaction shifts to the left.
C. Reaction shifts to the left.
Consider the following exothermic equilibrium in a sealed vessel: 2HNO3(aq) + K2SO3 (aq) « SO2(g) + H2O(l) + 2KNO3(aq) What happens to the equilibrium reaction if gaseous argon is added to the vessel at constant pressure? A. Reaction shifts to the left. B. No change to the reaction. C. Reaction shifts to the right.
C. Reaction shifts to the right.
What type of reaction are we going to study the determination of the equilibrium constant in this experiment? A. redox reaction B. acid and base neutralization reaction C. acid dissociation reaction D. precipitation reaction
C. acid dissociation reaction using a weak acid indicator
What happens to the amount of carbon dioxide if an additional amount of CaCO3(s) is added the reaction vessel after the reaction reaches equilibrium? CaCO3(s) « CaO(s) + CO2(g) A. decrease B. increase C. no change
C. no change
Which of the following reagent won't be used in this experiment? A. 0.2 M NaOH B. 0.2 M HCl C. pH indicatior D. Deionized Water
C. pH indicatior
Which graph are we NOT generating in this experiment? A. Temperature vs. Volume B. pH vs. Time C. pH vs. Volume HCl added D. Volume vs. Pressure
C. pH vs. Volume HCl added
Why do we need a reference sample for the measurements in this experiment? A. to remove the interference of the solvent of the sample solution B. The reference sample contains the species we need to study. C. to subtract the amount of light that is absorbed by everything but the sample being studied (cuvet, water, etc.) from the total absorbance. D. The reference sample can help us to determine the transmittance of the solvent.
C. to subtract the amount of light that is absorbed by everything but the sample being studied (cuvet, water, etc.) from the total absorbance.
Acid-base indicators are A. strong acids B. strong bases C. weak acids D. weak bases
C. weak acids
The goal of this experiment is A. To determine the activation energy of the reaction of iodide and persulfate. B. To study the effect of a catalyst on the reaction rate of the reaction of iodide and persulfate. C. To study the reaction mechanism of the reaction of iodide and persulfate. D. Both A and B
D. Both A and B
Explain the term parallax in the context of reading a meniscus and how you would avoid any error that might be introduced by parallax? A. Parallax error is the apparent displacement of an object as seen from two different viewpoints that are not in line with the object. The meniscus must be consistently be read from the top of the graduated cylinder. B. Parallax provides the depth perception necessary for our measurement. The meniscus must be read consistently at arm's length. C. Parallax provides the depth perception necessary for our measurement. The meniscus must be read consistently from the top of the graduated cylinder. D. Parallax error is the apparent displacement of an object as seen from two different viewpoints that are not in line with the object. The meniscus must consistently be read at eye level.
D. Parallax error is the apparent displacement of an object as seen from two different viewpoints that are not in line with the object. The meniscus must consistently be read at eye level.
Which chemical reaction is not applied in the lab? A. Complexing salicylic acid and iron(III) ion to produce tetraaquasalicylatoiron(III) complex B. Hydrolyzing acetylsalicylic acid with sodium hydroxide to form salicylate dianion and acetate ion. C. Converting salicylate dianion to salicylic acid In the presence of acid D. Synthesizing aspirin from salicylic acid and acetic anhydride
D. Synthesizing aspirin from salicylic acid and acetic anhydride
A proper Beer's Law plot shows A. a linear relationship when plotting Concentration vs. Absorbance B. a logarithmic relationship when plotting Concentration vs. Absorbance C. a logarithmic relationship when plotting Absorbance vs. Concentration D. a linear relationship when plotting Absorbance vs. Concentration
D. a linear relationship when plotting Absorbance vs. Concentration
How do we determine the equilibrium constant of bromothymol blue and bromophenol blue in this experiment? A. by measuring the equilibrium concentrations and then calculate K using the equilibrium constant expression formula. B. by measuring pH with pH papers and then calculate K using the equilibrium constant expression formula. C. by measuring absorbance with a spectrophotometer and then calculate K using the equilibrium constant expression formula. D. by measuring the pH with a pH probe and recording absorbance spectra, then calculate K using the equilibrium constant expression formula.
D. by measuring the pH with a pH probe and recording absorbance spectra, then calculate K using the equilibrium constant expression formula.
A catalyst can ______ the reaction rate by ______ the activation energy with a different reaction mechanism. A. decrease, increasing B. increase, increasing C. decrease, decreasing D. increase, lowering
D. increase, lowering
In order to calculate the molality of a solution, we need the following information except: A. mass of the solute B. molar mass of the solute C. mass of the solvent in kilograms D. molar mass of the solvent.
D. molar mass of the solvent. We only need kg of solvent
A third order reaction, 2A + B + C ® D + E, has a rate constant with unit of M-2S-1. The rate of the reaction doubles if the concentration of A is doubled. It is also found that varying the concentration of C does not change the rate of the reaction. What is the rate law of the reaction? A. rate = k[A]2[B][C] B. rate = k[A]2[B][C]0 C. rate = k[A][B][C] D. rate = k[A][B]2
D. rate = k[A][B]2
Each person must complete a set of data sheets according to the sample data sheet in manual. On each datasheet, which of the following information must be included on the datasheet? A. The reagents, amount, concentration, and associated cautions for each Part. B. List the Observations and Results portion on the datasheet so you can fill in them as you complete your experiment in lab. C. Your name, lab bench, and the date must be on each data sheet. D. The balanced net ionic equation for each equilibrium. E. All of the above.
E. All of the above.
Which of the following is not the goal of this experiment? A. Learn to use the pH probe B. Learn to collect data using the LoggerPro© program C. Learn to use the LabQuest© interface D. Learn to to measure the temperature and/or pH of various solutions and conduct a titration E. Learn to use a volumetric flask F. To explore the graphing and analysis capabilities of LoggerPro program
E. Learn to use a volumetric flask
Why using the plot of ion product vs. ion concentration to determine Ksp in this experiment won't be the best approach? A. The values of the ion product plotted on the y-axis are extremely small and make accurately extrapolating the data very difficult. B. The plot becomes most non-linear through the region in which we need to extrapolate the data. C. It will bring a higher error to the Ksp value. D. The plot of ion products vs Debye-Huckel ratio is a linear graph and gives more reliable extrapolating than a curve. E. A and B F. All of the aboves
F. All of the aboves
