Day 1 - ARC Anachem and Phychem

Question 1

A solution with 8.5% acetone and 91.5% water by mass has a density of 0.9867 g/ml. What mass of acetone is present in 7.5L of the solution?
a. 0.424 kg
b. 0.629 kg
c. 1.041 kg
d. 0.085 kg

Answer 1

B

Question 2

In normla blood, there are about 5.4x109 red blood cells per ml. The volume of a red blood cell is about 90x10-12 cm3, and its density is 1.096 g/ml. How many liters of whole bloodwould be needed to collect 0.5 kg of red blood cells?
a. 1.1 L
b. 0.9 L
c. 0.6 L
d. 2.1 L

Answer 2

B

Question 3

An empty 3L bottle weighs 1.7kg. Filled with a certain wine, it weighs 4.72kg. The wine contains 11.5% ethyl alcohol by mass. How many grams of ethyl alcohol are there in 250 ml of this wine?
a. 28.9g
b. 38.2g
c. 11.5g
d. 18.7g

Answer 3

A

Question 4

An aqueous solution that is 5.3% LiBr by mass has a density of 1.04 g/mL. What is the molarity of this solution?
a. 0.563 M
b. 0.634 M
c. 0.0633 M
d. 0.0563 M

Answer 4

B

Question 5

A teardrop with a volume of 0.5ml contains 0.5mg salt. What is the molarity of the salt in the teardrop?
a. 0.04M
b. 0.03 M
c. 0.01 M
d. 0.02 M

Answer 5

D

Question 6

A solution of calcium chloride is prepared with a 1L volumetric flask. A 60gsample of CaCl2 is added to a small amount of water in the flask, and then additional wateris added to bring the total volume of solution to 1L.What is the concentration of calcium chloride in units of molarity?
a. 0.29 M
b. 0.38 M
c. 0.54 M
d. 0.61 M

Answer 6

C

Question 7

Organic carbon in seawater can be measured by oxidizing to CO2 with K2S2O8, followed by gravimetric determination of CO2 trappedby a column of Ascarite. Water weighing 6.234 g produced 2.378 mg of CO2 (44.01) . Find the ppm carbon in the seawater
a. 223.5
b. 104.01
c. 85.9
d. 456.6

Answer 7

B

Question 8

A solution containing 1.263g of unknown potassium compound was dissolved in water and treated with excess sodium tetraphenylborate solution to precipitate 1.003g of insoluble K+ B(C6H5)4- (358.33). FInd the weight %K in the unknown.
a. 12.34
b. 57.62
c. 8.643
d. 32.05

Answer 8

C

Question 9

A 0.2386g sample contained only NaCl and KBr. it was dissolved in water and required 48.4ml of 0.04837M AgNO3 for complete titration of both halides, giving AgCl and AgBr precipitates. Calculate the weight % of Br in the solid sample.
a. 11.45%
b. 85.23%
c. 56.35%
d. 43.16%

Answer 9

C

Question 10

A 10.231g sample of window cleaner containing ammonia was diluted with 39.466g of water. Then, 4.37g of solution were titrated with 14.22 ml of 0.1063M HCl to reach a bromocresol green endpoint. Find the weight % of NH3 in the cleaner.
a. 10.2%
b. 14.5%
c. 5.76%
d. 2.85%

Answer 10

D

Question 11

Find the concentration of H+ in a solution whose pH is 11.65
a. 2.24x10-12 M
b. 4.47x10-3 M
c. 4.23x10-7 M
d. 7.24x10-11 M

Answer 11

A

Question 12

A 0.0722 M acid has a pH of 3.11. What is the Ka of the acid?
a. 4.2x10-6
b. 8.44x10-7
c. 8.44x10-6
d. 4.2x10-7

Answer 12

C

Question 13

A 0.0222 M solution of HA is 0.15% dissociated. Calculate the pKa for this acid.
a. 4.7
b. 3.7
c. 7.3
d. 7.4

Answer 13

C

Question 14

Assume that the density of compacted waste to be 490 kg/m3. What is the ratio of HPO4 2- / H2PO4 - in a phosphate buffer of pH 7.9? pKa = 7.21
a. 5:1
b. 2:1
c. 3:1
d. 4:1

Answer 14

A

Question 15

Find the pH of a solution prepared from 2.53g of oxoacetic acid (74.04), 5.13g of potassium oxoacetate (112.13), and 103g of water, Ka= 3.5x10-4.
a. 5.23
b. 3.58
c. 4.35
d. 2.87

Answer 15

B

Question 16

The phosphate in a 3000 mg sample of industrial detergent was precipitated by the addition of 1g of AgNO3. The solution was filtered and the filtrate required 18.23 ml of 0.1377M KSCN. Calculate the percentage of phosphate in detergent. AgNO3 = 169.87 g/mol, PO4 3- = 94.97 g/mol
a. 3.56%
b. 5.35%
c. 7.12%
d. 10.69%

Answer 16

A

Question 17

A 25 ml sample containing Fe 3+ was treated with 10ml of 0.0367 M EDTA to complex all the Fe3+. The excess EDTA was then back-titrated, requiring 2.37 ml of 0.0461 Mg 2+. What was the concentration of Fe3+ in the original solution?
a. 0.0103 M
b. 0.0124 M
c. 0.0205 M
d. 0.0065 M

Answer 17

A

Question 18

A 5ml aliquot of bleach (density = 1.61 g/ml) was diluted and treated with excess KI to convert hypochlorite to chloride. The liberated I2 required 22.85 ml of 0.214 M NA2S2O3 for titration. Calculate the %ClO in the bleach.
a. 4.18%
b. 1.56%
c. 2.72%
d. 3.12%

Answer 18

B

Question 19

Calculate the weight of primary standard Na2C2O4 (134 g/mol) necessary to react with 25 ml of 0.2005 M KMnO4 in acidic medium.
a. 0.671 g
b. 1.679 g
c. 1.343 g
d. 2.687 g

Answer 19

B

Question 20

A 4.03 g sample of solid conaining only NaNO2 (68.995) and NaNO3 was dissolved in 500 ml. A 25 ml of this solution was treated with 50 ml of 0.1186 M Ce 4+ in strong acid for 5 min to convert all nitrite to nitrate, and excess Ce 4+ was backtitrated with 31.13 ml of 0.04289 M ferrous ammonium sulfate. Calculate the weight % NaNO2 in the solid.
a. 22.45%
b. 63.58%
c. 43.22%
d. 78.67%

Answer 20

D

Question 21

By what factor are the root-mean-square speeds changed if a gas is heated from 300K to 400K?
a. 1.15
b. 1.33
c. 1.67
d. 1.75

Answer 21

A

Question 22

In a normal adult at rest the average speed of flow of blood through the aorta is 0.33 m/s. The radius of the aorta is 9 mm and the viscosity of blood at body temperature, 37degC, is about 4x10-3 kg/m-s. Calculate the pressure drop along a 0.5 m length of the aorta.
a. 26 Pa
b. 43 Pa
c. 65 Pa
d. 77 Pa

Answer 22

C

Question 23

A gas obeys the Van der Waals equation with Pc = 3.04x10^6 Pa and Tc = 473 K. Calculate the Van der waals constant b for this gas in m3/mol
a. 1.62 x 10-4
b. 2.97 x 10-4
c. 3.08 x 10-4
d. 4.41 x 10-4

Answer 23

A

Question 24

O2 gas is effused through a pinhole in 5s. How long will it take an equivalent amount of CO2 to effuse under the same condtions?
a. 4.3 s
b. 3.8 s
c. 5.9 s
d. 2.2 s

Answer 24

C

Question 25

What is the ionic strength in M of a solution that is 0.1 M KNO3 and 0.2 M K2SO4? a. 0.5 b. 0.6 c. 0.7 d. 0.8

Answer 25

C

Question 26

Calculate the degree of dissociation for 0.01 m solution of HCl that freezes at 273.114K a. 0.96 b. 0.94 c. 0.88 d. 0.8

Answer 26

B

Question 27

A 0.08m weak solution of electrolyte ionizing into two ions freezes at -0.208degC. Calculate the degree of dissociation. a. 11.8 b. 60.2 c. 88.2 d. 39.8

Answer 27

D

Question 28

Of the following aqueous solutions, the one with the lowest freezing point is: a. 0.01m MgSO4 b. 0.011 m NaCl c. 0.018 m CH3CH2OH d. 0.008 m MgCl2

Answer 28

D

Question 29

A compound is 42.9% C, 2.4% H, 16.7% N, and 38.1% O by mass. Addition of 6.45 g of this compound to 50 ml of benzene (0.879 g/ml, Kf = 5.12 K/m) lowers the freezing point from 5.53 to 1.37degC. What is the molecular formula of this compound? a. C4H6NO4 b. C6H4N2O4 c. C6H6N4O2 d. C4H4N2O2

Answer 29

B

Question 30

A constant current was passed through a solution of CuSO4 for 1 hr and 0.04g of copper was deposited. What is the current? a. 33.76 mA b. 8.44 mA c. 16.88 mA d. 4.22 mA

Answer 30

A

Question 31

A technician is plating a faucet with 0.86 g of chromium from an electrolytic bath containing aqueous Cr2(SO4)3. If 12.5 min is allowed for the plating, what current is needed? The atomic mass of Cr is 52.00 amu. a. 3.368 A b. 3.863 A c. 6.383 A d. 8.336 A

Answer 31

C

Question 32

What mass of magnesium (24.31) is produced when 100,000 A is passed through a MgCl2 melt for 1 hour if the yield of magnesium is 85%? a. 38.55 kg b. 55.38 kg c. 58.35 kg d. 83.55 kg

Answer 32

A

Question 33

What is the cell potential for the following redox reaction ran at stadard condtions? Cu2+ (aq) + Zn (s) = Cu (s) + Zn2+ (aq) The standard half-cell potentials of Cu2+/Cu and Zn2+/Zn are 0.34V and -0.763 V, respectively. a. -0.423 V b. 0.423 V c. 1.103 V d. -1.103 V

Answer 33

C

Question 34

What is the value of the equilibrium constant K for the reaction between copper metal and ferric ion in aqueous solution at 25degC? The half-cell potentials Cu2+/Cu and Fe3+/Fe2+ are 0.34V and 0.771V, respectively. a. 4x10^14 b. 0.0441 c. 1553 d. 2.4x10-11

Answer 34

A

Question 35

Calculate the change in molar Gibbs free energy of liquid water treated as an incompressible fluid when the pressure is increased form 1 bar to 2 bar at 298 K. a. 0.9 J/mol b. 1.8 J/mol c. 2.7 J/mol d. 3.6 J/mol

Answer 35

B

Question 36

Determine the value of Kc from Kp = 14800 for the following reaction at 184degC: 2NO (g) + O2 (g) = 2NO2 (g) a. 6.74 x 10^5 b. 7.66 x10^5 c. 4.35 x 10^2 d. 5.55 x 10^5

Answer 36

D

Question 37

For the reaction: 2NO2 (g) = 2NO (g) + O2 (g) Kc = 1.8x10-8. At 184degC, the value of Kc for the reaction: NO (g) + 1/2 O2 (g) = NO2 (g) is: a. 0.9 x 10^6 b. 7.5 x 10 ^2 c. 5.6 x 10 ^5 d. 2.8 x 10 ^5

Answer 37

B

Question 38

In a study of the equilibrium: H2 + I2 = 2HI 1 mol of H2 and 3 mol of I2 gave rise at equilibrium to x mol of HI. Addition of a further 2 mol of H2 gave an additional x mol of HI. What is K at the temperature of the experiment? a. 3 b. 4 c. 5 d. 6

Answer 38

B

Question 39

The equilibrium constant Kp for the reaction: I2 (g) + C5H8 (g) = 2HI (g) + C5H6 (g) varies with temperature according to the equation: log (Kp, bar) = 7.55 - (4844/T, K) If I2 and C5H8 are initially at 400degC and at concentrations of 0.1 M, calculate the final equilibrium concentration of cyclopentene. a. 0.07 M b. 0.02 M c. 0.09 M d. 0.05 M

Answer 39

A

Question 40

The equilibrium constant for the reaction below is 20 at 40degC: H2 + I2 = 2HI The vapor pressure of solid iodine is 0.1 bar at that temperature. If 12.7 g of solid iodine are placed in a 10L vessel at 40degC, what is the minimum amount of hydrogen gas that must be introduced in order to remove all the solid iodine? a. 0.012 mol b. 0.027 mol c. 0.044 mol d. 0.064 mol

Answer 40

D