Project #89699 - Chem 115 Exam two-chapters 14,15,16,17

pH =    -log [H+]                                              pOH = -log [OH-]                               14.00 = pH + pOH

[H+] =  antilog(pH)    or 10-pH                        [OH-] = antilog(pOH) or 10-pOH              Kw = [H+][OH]= 1.0 x 10-14   

pKa = -log(Ka)                                                                                                            Kw =  Ka Kfor conj. pair       

Weak acids in water: Ka = [H+][A-] / [HA]init                  Weak bases in water: Kb = [-OH] [BaseH] /[Base]init                      % ionization = [H+] / [HA]init x 100 %                        % ionization = [A-] / [HA]init x 100 %

 

 

ΔSreaction° = SmS° (products) - SnS° (reactants)          Units:  J / (mole . K)                ΔG = ΔH – TΔS

Practice Exam Section: Please show all work for full credit on this assignment.

 

1.  Rank in order of increasing acidity: (Note: the end of a line represents a Carbon atom)

            a.                                                                     b.

           

                         

            c.     HF

 

                    

 

2.         a. Define pH and pOH

            b. Write equations for converting pH and [H+]

            c. Write equations for converting pOH and [OH-]

            d. Write the equation relating pH and pOH

            e. Write the equation for relating Kw to the hydroxide/hydrogen ions.

                         

 

3.   Complete the table below

pH

pOH

[H+]

[OH-]

Acidic/Basic/Neutral

9.68

 

 

 

 

 

8.90

 

 

 

 

 

7.8 x 10-5

 

 

 

 

 

1.1 x 10-13

 

13.1

 

 

 

 

 

8.07

 

 

 

 

4. What is the pH of a 0.075 M solution of hydroiodic acid, HI?

   

5. Calculate the pH for each of the following

a. 0.60 M HNO2Ka = 4.0  10–4.                                  b. 0.16 M solution of HOCl, Ka = 3.5  10–8.

 

 

6.  Calculate the pH for each of the following weak bases.

            a. 0.570 M solution of aniline,  Kb = 7.4 × 10-10    b. 0.380 M solution of ethylamine, Kb = 4.3 × 10-4

                       

 

 

7.  Predict whether the following salts will from a solution that is acidic, basic or neutral.

            a. FeCl3           e. NaF                         b. NH4ClO                  f. LiClO4                     c. K2CO3

           

8.  Calculate the Ka value for a 1.0 M solution of a weak acid that is

            a. 5.0% ionized           b. 0.50 % ionized                    c. 20. % ionized

           

 

 

9.  Select which of the following will produce a buffered solution.

            a)         100 mL of 0.1 M Na2CO3 and 50 mL of 0.1 M HCl

b)         100 mL of 0.1 M NaHCO3 and 25 mL of 0.2 M HCl

            c)         100 mL of 0.1 M Na2CO3 and 75 mL of 0.2 M HCl

            d)         50 mL of 0.2 M Na2CO3 and 5 mL of 1.0 M HCl

            e)         100 mL of 0.1 M Na2CO3 and 50 mL of 0.1 M NaOH

 

10.  Calculate the pH in a 2.0-liter buffered solution that is 0.82 M NH3 (Kb = 1.8 x10–5) and 0.26 M NH4F.

 

 

 

 

11.  Calculate the pH of a 1.00 M acetic acid (Ka = 1.8 x 10–5) after adding 0.0040 M NaOH.

               

 

 

12.  Calculate the  pH after adding 0.30 L of 0.020 M KOH  to a 1.0-liter solution containing 0.25 M HF and 
       0.66 M NaF (Kfor HF is 7.2  10–4).

 

 

 

13.       What is the molarity of a sodium hydroxide solution if 27.9 mL of this solution reacts exactly with 22.30 
mL of 0.253 M sulfuric acid?

 

 

14.       Calculate the pH if 25 mL of 0.750 M HCl are titrated with 100. mL of 0.346 M NaOH.

 

 

 

15.       Calculate Ksp if the solubility of CaSO4 in pure water at 0oC is 1.13 gram(s) per liter.

 

 

16.  Silver chromate, Ag2CrO4, has a Ksp of 9.00 x 10–12. Calculate the solubility in mol/L of silver chromate.

 

 

 

17.  ΔS° for the following reaction is -258.2 J/mol∙ K. Calculate S° for C3H4.

                C3H4(g) + 2 H2(g) → C3H8(g)

            S°                 130.6     269.9 J/mol∙deg

           

 

 

18.  Indicate if entropy will increase or decrease.

a)         precipitation                                       

b)         gaseous reactants forming a liquid

c)         a burning piece of wood                    

d)         melting ice                              

e)         evaporation of 1 mol of CCl4(l)         

f)         mixing 5 mL ethanol with 25 mL water        

g)         compressing 1 mol Ne at constant temperature from 1.5 L to 0.5 L

h)         raising the temperature of 100 g Cu from 275 K to 295 K   

i)          grinding a large crystal of KCl to powder     

 

19.   Calculate ΔG° at 25°C for          N2O4(g) → 2 NO2(g)     ΔH° = 58.03 kJ     ΔS° = 176.7 J/K

             

 

20.  Calculate ΔS°rxn or the reaction,                                    CaCO3(s) → CaO(s) + CO2(g) 

                                                                        S° (J/mol K)     88.70              39.75       213.6

 

Subject Science
Due By (Pacific Time) 10/28/2015 09:00 pm
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