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化学考试代写 Chem代写 Midterm代写

2021-12-02 09:13 星期四 所属: 化学代写 浏览:398

Chem 1220 Midterm 2 

化学考试代写 1.If 1.00 mole of HF(g), 0.500 mole of H2(g), and 0.750 mol of F2(g) are mixed in a 5.00 L flask, what is the reaction quotient and

1.

If 1.00 mole of HF(g), 0.500 mole of H2(g), and 0.750 mol of F2(g) are mixed in a 5.00 L flask, what is the reaction quotient and the net direction to reach equilibrium

H2(g) + F2(g) ⇌ 2 HF(g)           Kc = 100

(a) Q = 2.66, the system is at equilibrium

(b) Q = 0.375, the equilibrium shifts to the right

(c) Q = 2.66, the equilibrium shifts to the left

(d) Q = 0.375, the equilibrium shifts to the left

(e) Q = 2.66, the equilibrium shifts to the right

 

2.

Given the following equilibrium

CO(g) + 2 H2(g) ⇌ CH3OH(g)

A chemist introduces 0.42 mol of CO and 0.42 mol of H2 into a 1.00 L reaction vessel. Once the mixture comes to equilibrium there are 0.29 mol of CO remaining. What is the equilibrium constant, Kc  at this temperature?

(a) 2.80

(b) 0.357

(c) 14.5

(d) 17.5

(e) None of the above

 

3.

The reaction

PCl5(g) ⇌ PCl3(g) + Cl2(g)     ΔH° = 88 kJ

Is at equilibrium. Which of the following changes will shift the equilibrium to the right?

(1) removing Cl2
(2) decreasing the temperature
(3) increasing the volume of the reaction vessel

(a) 1 only

(b) 2 only

(c) 3 only

(d) 1 and 3

(e) 1 and 2

 

4.  化学考试代写

Consider the following molecules CH3NH2, CH3CH2OH, CH3CH2CO2H. Amongst these three _______ is a weak acid, _______ is a weak base, and _______ is neither an acid nor a base in aqueous solution.

(a) CH3CH2CO2H, CH3NH, CH3CH2OH

(b) CH3CH2CO2H, CH3CH2OH, CH3NH2

(c) CH3NH, CH3CH2OH, CH3CH2CO2H

(d) CH3CH2OH, CH3NH, CH3CH2CO2H

(e) CH3NH, CH3CH2CO2H, CH3CH2OH

 

5.

Given the following Ka values determine which species is the strongest base

HF, Ka = 6.8 × 104     HNO2, Ka = 4.5 × 104     HCNO, Ka= 2.2 × 104

(a) F

(b) NO2

(c) CNO

(d) HF

(e) HCNO

 

6.

If 0.500 mol of H2(g) and 0.500 mol of I2(g) are placed in a 2.00 L container at a temperature where the following equilibrium exists:

H2(g) + I2(g) ⇌ 2 HI(g)       Kc = 125

What concentration of HI(g) is present once the system comes to equilibrium?

(a) 0.424 M

(b) 0.0405 M

(c) 0.380 M

(d) 0.230 M

(e) 0.212 M

 

7.

What is the % ionization of a 0.015 M solution of hypochlorous acid, HClO (Ka = 3.0 × 10-8 )?

(a) 2.1 × 10-5 %

(b) 0.0014 %

(c) 0.14 %

(d) 1.5 %

(e) 14 %

 

8.  化学考试代写

What is the pH of a 0.050 M solution of H2SO4 (Ka2 = 0.012)?

(a) 1.01

(b) 1.23

(c) 1.30

(d) 1.28

(e) 2.07

 

9.

Arrange the following molecules/ions from the weakest to strongest base: Cl , OH , O2, NH.

(a) Weakest base Cl < NH3 < O2 < OH Strongest base

(b) Weakest base O2 < Cl < NH3< OH Strongest base

(c) Weakest base Cl < NH3 < OH < O2 Strongest base

(d) Weakest base Cl < O2< NH3 < OH– Strongest base

(e) Weakest base NH< Cl < OH < O2 Strongest base

 

10.

An solution of Ca(OH)2 is determined to have a pH of 11.24. What is the concentration of Ca(OH)2 in this solution?

(a) 5.75 × 10-11 M

(b) 1.74 × 10-3 M

(c) 8.69 × 10-4 M

(d) 3.47 × 10-3 M

(e) 2.76 × 10-1 M

11.

Both bromous acid (HBrO2) and hypobromous acid (HBrO) are weak acids. In both molecules the hydrogen atom is bound to _______ , yet the bond is more polar in ______ which makes it a stronger acid (larger Ka).

(a) bromine, HBrO

(b) bromine, HBrO2

(c) oxygen, HBrO

(d) oxygen, HBrO2

 

12.  化学考试代写

What is the pH of a 0.50 M solution of NaBrO? The Ka of HBrO is 2.5 × 10-9 .

(a) 2.85

(b) 3.20

(c) 9.67

(d) 10.80

(e) 11.15

 

13.

How many of the following salts will form acidic solutions when dissolved in water?

AlCl3             NaBr           NaClO            Na2SO3                 CH3NH3NO3

(a) 0

(b) 1

(c) 2

(d) 3

 

14.

A buffer is prepared by adding 10.0 g of NH4Cl (molar mass = 53.5 g/mol) to 250.0 mL of 1.00 M NH(K = 1.8 × 10-5 ) solution. What is the pH of this buffer? Ignore any changes in volume that occur on mixing.

(a) 10.14

(b) 9.98

(c) 9.38

(d) 9.13

(e) 4.87

 

15.  化学考试代写

If 8.00 mL of 2.00 M HNO3(aq) solution are added to the buffer from the previous problem what is the new pH?

(a) 10.01

(b) 9.44

(c) 9.31

(d) 4.93

(e) 4.81

 

Physical Constants

R = 8.314 J∙mol-1∙K-1
R = 0.0821 L∙atm∙mol-1 ∙K-1
1 F = 96,500 C∙mol-1
1 F = 96,500 J∙V-1∙mol-1
NA = 6.022 x 1023 mol-1
h = 6.626 x 10-34 J∙s
c = 2.998 x 108 m∙s-1
0° C = 273.15 K
KW = 1.00 x 10-14 at 25° C

 

化学考试代写
化学考试代写

 

 

 

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