Homework answers / question archive / Question 1 (1 point) Consider a reaction A + B -> Products for which the rate can be expressed as Rate = k [A]^m [B]^n An experimenter prepares several reaction mixtures and determines the initial reaction rates under these different conditions

Question 1 (1 point) Consider a reaction A + B -> Products for which the rate can be expressed as Rate = k [A]^m [B]^n An experimenter prepares several reaction mixtures and determines the initial reaction rates under these different conditions

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Question 1 (1 point) Consider a reaction A + B -> Products for which the rate can be expressed as Rate = k [A]^m [B]^n

An experimenter prepares several reaction mixtures and determines the initial reaction rates under these different conditions. The data obtained for several experiments are in the table below. Which experiments (run#) can be used to determine n?

Run#	Initial [A]_0	Initial [B]_0	Initial Rate [v]0
1	1.00M	1.00M	1.25*10^-2 M/s
2	1.00M	2.00M	2.5*10^-2 M/s
3	2.00M	2.00M	2.5*10^-2 M/s

 

a) 1 and 3

b) 2 and 3

c) 1 and 2

d) 1. 2 and 3

               

Question 2(1 point)

 While studying the following reaction:

4 As + 3 02 — 2 As203

 it is found that under certain conditions, the rate of production of As2o3 is 0.130 mol/s. Determine the rate of consumption of As under the same conditions. Give your answer in mol/s to three significant digits.

Your Answer.

 

Answer

 

Question 3 (1 point)

 The solubility product constant of Pbl2 is 1.4 x 10- 8 What is the concentration of lead ions in a saturated solution lead (II) iodide in M?

 1.2 x 10-4

 1.4 x 10-8

1.5 x10-3

2.4 x 10-3

3.4 x 10-3

 

Question 4 (1 point)        The newly discovered element Tallullium, symbol Tu, forms the following compounds:

 Tu032- has Kb = (6.230x10^-4)

HTu03- has Kb = (1.18x10^-7)

Calculate Ka for HTu03- to three significant digits.

 Note: Your answer is assumed to be reduced to the highest power possible. Your Answer: -

*10 Answer

Question 7 (1 point)

Phosphoric acid dissociates in water in 3 steps:

H3PO4(aq)+H2o(1)=H3o+(aq)+H2po4-_(aq),

Kal=7.5*10-3

H2PO4-(Aq)+H2o(1)=H3o+(aq)+Hpo4-2(aq),

Ka2=6.2*10-8

Hpo42-(aq)+H2o(1) =H3o+(aq)+Po4 3-(aq)-,

Ka3=3.6*10-13

 

 

Which of these equilibrium reactions is crucial for the pH of phosphoric acid?

a) the first dissociation

b) the second dissociation

c) all dissociation combined

d) the third dissociation

 

Question 9)

Tallula adds 0.182 mol of a weak acid to a flask and makes up the volume to 1.000 L.The pH of the solution is found to be 2.28 at equilibrium. Calculate the percent ionization to three significant digits. Give your answer as a percent (but do not include the "%" symbol).

Your Answer:

Answer

Question 10 (1 point) A buffer solution is prepared by dissolving 0.100 mole of methylamine, CH3NH2, and 0.060 moles of methylammonium chloride, CH3NH3CI, in enough water to make 0.250 L solution. For methylamine, Kb=4.38 -10-4. Calculate pH of solution after 0.020 moles of HCI are added.

 a) 9.82

 b) 10.64

c) 11.03

d) 11.59

 

 

Question 11(1Point) Tallula is studying the following reaction: X — Y + Z

She measures[X) as a function of time. She finds that if she plots ln[X] versus time, the result is a straight line with slope -5.

The rate law  for this reaction is:

rate = _5 • [X]2

t1/2 = -1/5 • [X]2

rate = 5 • [X]

rate =[X]-5

rate = _5 • [X]2

t1/2 = -0.1386

 

Question 12 (1 point)

Calculate the PH of a buffer solution prepared by dissolving 0.10 mole of cyanic acid HCNO, and 0.50 moles of sodium cyanate NACNO in enough water to make 0.500 L solution for HCNO, K2 =2.0 -10^4

1. 4.40
2. 5.50
3. 2.20
4. 3.30

Question 14(1 point) Tallua studying the following chemical reaction: is  A + B→ C

She measures the initial rate of production of C under various conditions. Her are shown in the table below.

Trial #	initial [A] (M)	initial [B] (M)	initial rate of production of C (M/H)
1	0.50	0.10	2.5
2	1.00	0.10	5.0
3	0.50	0.20	5.0

 

Determine the rate law for this reaction.

A) Rate=k(b)2

B) rate = k [A]2 [B]2

 c) rate = k [A] [B]2

d)rate=k[B]

e) rate = k [A] [B]

 f) rate = k [A]2

 g) rate = k [A]

h) rate = k [A]2 [B]          

 

Question 15 (I point)

Look at the table and list metal ions according to the pH of the solution they will produce when dissolved in water, starting from the lowest pH to the highest pH.

Cr3+	3.95	1.12-10^4
Cu2+	7.34	4.57-10^8
Fe3+	2.17	6.76-10^3
Pb2+	7.8	1.58-10^8

 

Iron (III) ion

Copper (II) ion

Lead (11) ion

Chromium (III) ion

 

Question 16 (1 point)

Ka(H2S03) = 1.5.10-3

Ka(HS03) = 1.0.10-7

If NaHSO3 is added to water,

 

1. the solution will be basic because Ka(HS03-) < Ka(H2S03) .
2.  the solution will be acidic because Ka(HS03-) < Ka(H2S03) . _
3.  the solution will be neutral because Ka(HS03) = Kw .
4.  the solution will he acidic because Ka(HS03-) > Kb(HS03 )
5.  the solution will be neutral because it is a sodium salt.
6.  the solution will be basic because Ka(HS03) < Kb(HS03) .

 

Question 18 (1 point) _-Using the table below list the order of the conjugate bases from weakest to strongest of the following acids:

• HCO3—

 • CH3 C00H -4

• CH2 C1COOH

 •H-2 CO3

 Note: CH3 COQH is a weaker acid than CH2 C1COOH

 ACID

 HC1 H2504 HNO3 H30+ (STRONG ACID)

 [HSO4 - H3PO4 HF CH,CH3C00H

 

(Weak acid)

HSO4 Fl3PO4 HF CH3C00° H2CO3 H25 H2PO4 NE4+ HCO3- _HPO42-

H20 (Acd strength increasing)

0H-- -H2 __CH 4 (Negligible acidity)

CO2, HCO3, CH3C00- - , CH2 C1C00-

CH3 COO, CH2 C1C00- , HC0-3 , CO23

C023- HCO3, , CH2 C1C00- , CH3 COO-0

CH2 C1C00— CH3 COO— ,HCO-, ,CO23

 

Question 19 (1 POint)

 The data in the table below were obtained for the reaction:

2 CIO, (aq) + 2 0h- (aq) -C103- (aq) + CIO2- (aci) + H20 (1)

Experiment Number	{c1o2}(m)	{oh-}(m)	Initial Rate (M/s)
1	0.060	0.030	0.0248
2	0.020	0.030	0.00276
3	0.020	0.090	0.00828

What is the order of reaction with respect to C102?

? 3                       

? 1

? 2       

? 4

?  0

 

Question 20 (1 point) Calculate the pH of a 0.803 M solution of Na2C204• Give your answer to three decimal places.

Note: Ka for HC204- = 6.53.10-5

Your Answer:

 

 Question 21 (1 point)  When a 0.169-M solution of a certain weak acid is prepared, it is found that the percent ionization is 17.59%. Calculate the Ka for this weak acid. Give your answer to three significant digits.

Your Answer:

 

 

Question 22 (1 point) What is the pH of an 0.03059 mol/L solution of KOH? Give your answer to three decimal places.

 Your Answer:

 

Question 23 (1 point)

A study of a popular pesticide's decomposition in soil has revealed that it follows the — second order kinetics and its half-life at certain conditions is 2.51 days. A farmer   applies the pesticide at a rate of 1.56 kilograms per hectare of soil. Calculate the rate constant of the pesticide's decomposition in kg ha-1 d-1. Give your answer to three decimal places.

  Your Answer:

 

 

 

Question )24(1 Poind) Tallula is studying glyphosate, a weed killer. She finds that the concentration of gluphosate in the soil  following an application is given by the equation:

In [G] = —kt + 4.6

Where (G) is the concentration of glyphosate in ppm, k is a constant given by  k=0.0195, and tis the time in days since the weed killer was applied.      

Calculate the concentration of glyphosate in the soil 58 days after application. Give Your answer in ppm to one decimal place.

Your Answer

 

 

Question 25 (1 point)

Use the table below to determine if the following statement is true:

 The equilibrium for the reaction HF+ CO^2_3: - F-+ HCO3- lies further to the right.

100% ionized in H2O

 

ACID	Base
HC1	C1-
HSO4	SO42_
HNO3	HNO3
H3O+(AQ)	H2O
HSO4-	SO42_
H3PO4	H2PO4
HF	F-
HC2H3O2	C2H3O2-
H2S	HS-
H2PO4	HPO42-
NH4+	NH3
HCO3	CO32-
HPO42-	PO43-
H2O	OH-
OH-	O2-
H2	H-
CH4	CH3-

 

True

False