Highlander Help

CHAPTER 16 BASIC

ACIDS I

Resources:

Have you found videos, websites, or explanations that helped you understand this chapter? Let us know and we'll add them to "Resources" part of this page for other students to use.


 

Question 1

What is the pOH of a solution where the [OH-] =7.74 x 10-3 M?
REPORT IT TO 2 DECIMAL PLACES.

pOH = -log[OH-]

Correct

 

Explanation

 pOH = -log(7.74e-3) = 2.11

 

Question 2

What is the pOH of a solution where the [H+] =3.71 x 10-11 M? REPORT IT TO 2 DECIMAL PLACES.


Correct

 

Explanation

 pH= -log(3.71e-11) = 10.43

pOH + pH = 14

pOH= 14 - 10.43

=3.57

 

Question 3

The pH is 1.37. What is the pOH?

Correct

 

Explanation

 pOH + pH = 14

pOH = 14 - 1.37 = 12.63

 

Question 4

The pOH is 0.94. What is the pH?

Correct

 

Explanation

 pOH + pH=14

pH= 14 - 0.94 = 13.06

 

Question 5

A solution with 6.5 mol HCl is mixed with a solution with 11.5 mol of NaOH. How many moles of OH- remain?

Acid-base neutralization

Correct

 

Explanation

 11.5-6.4 = 5 mol OH-

 

Question 6

A solution with 25.3 mol HCl is mixed with a solution with 11.8 mol of NaOH. How many moles of H+ remain?

Correct

 

Explanation

 Excess= HCl = 25.3-11.8 = 13.5 mol H+

 

Question 7

A solution containing 42.3 mol HCl is mixed with a solution containing 35.0 mol NaOH. The volume is 348 L. What is the final pH?


Correct

 

Explanation

 Excess= HCl = 42.3 - 35 = 7.3 mol / 348 L = 0.020977 [H+]

pH= -log [0.020977] = 1.68

 

Question 8

A solution with 44.8 mol HCl is mixed with a solution with 47.8 mol NaOH. The volume is 844 L. What is the final pH?

Neutralization and pH example 2

Correct

 

Explanation

 Excess = NaOH  = 47.8 - 44.8 = 3 mol/ 844 L = 0.00355 [OH-]

pOH= -log[0.00355]=2.45

14-2.45=11.55

 

Question 9

How many moles of H+ are in 203 mL of 0.52 M nitric acid, HNO3?

Calculating moles

Correct

 

Explanation

 0.203 L (0.52 M) = 0.10556 mol [H+]

 

Question 10

How many moles of OH- are in 758 mL of 0.42 M NaOH?

Correct

 

Explanation

 0.758 L (0.42 M) = 0.31836 mol [OH-]

 

Question 11

How many moles of OH- are in 528 mL of 0.26 M Ca(OH)2?

Correct

 

Explanation

 0.528 L ( 0.26 M) = 0.27456 [OH-]

 

Question 12

When 132 mL of acid is mixed with 480 mL of base, what is the new volume in L?

Correct

 

Explanation

 0.132 + 0.480 = 0.612 L

 

Question 13

439 mL of 0.500 M HCl is mixed with 217 mL of 0.380 M NaOH. What is the pH?

Correct

 

Explanation

 (0.439 L) (0.5 M) = 0.2195 mol H+

(0.217 L) ( 0.38 M)= 0.08246 mol OH-

[H+] - [OH-]= 0.13704 mol / 0.656 L = 0.2089 [H+]

pH= -log[0.2809]= 0.680

 

Question 14

205 mL of 0.330 M HBr is mixed with 240 mL of 0.570 M KOH. What is the pH?

Correct

 

Explanation

 (0.205 L) (0.33 M) = 0.06765 mol H+

(0.240 L) (0.57 M) = 0.1368 mol OH-

[OH-] - [H+] = 0.06915 mol OH- / 0.445 L = 0.155 M [OH-]

pOH = -log[OH-] = 0.80857

14-pOH=pH

pH= 13.19

 

Question 15

2.0 mL of 0.110 M HBr is mixed with 61.5 mL of 0.62 M HCl. What is the molarity of the H+?

Correct

 

Explanation

 (0.062 L)(0.110 M) = 0.00682 mol H+

(0.0615 L)(0.62 M) = 0.03813 mol H+

[H+]= (0.00682 + 0.03813)/ (0.62 + 0.0615) = 0.364

 

Question 16

21.7 mL of 0.630 M NaOH is mixed with 53.4 mL of 1.90 M LiOH. What is the molarity of the OH-?

Correct

 

Explanation

 (0.0217 L)(0.63 M) = 0.013671 mol OH-

(0.0534 L)  (1.9 M) = 0.10146 mol OH-

0.115131 mol OH- / (0.0751 L) = 1.533 [OH-]

 

Question 17

A solution contains 0.0247 M HBr and 0.150 M acetic acid. What is the pH?

Correct

 

Explanation

 (acetic acid is negligible (doesn't count) because  it's hella weak in comparison to [H+])

pH= -log[0.0247] = 1.607

 

Question 18

A solution contains 0.0172 M HNO3, 0.0341 M HI, and 0.220 M formic acid, HCOOH. What is the pH?

Correct

 

Explanation

 (formic acid is also hella weak)

pH= -log[0.0172 + 0.0341] = 1.2899

 

Question 19

A solution contains 0.137 M Ba(OH)2 (strong base) and 0.140 M ammonia, NH3 (weak base). What is the pH?

Correct



 

Explanation

 pOH = -log(2 * 0.137) = 0.562

pH= 14-0.5622= 13.44