Portage Learning Chem 210 - Module 2 exam

Question 1
pts


Scientific Calculator




The pH of a solution of 8.9 x 10-12 M NaOH is:


A. 8.9


B. 8.9 x 10-12


C. 4.8


D. 11


E. 2.9


A
B
C
D
Correct!

E

[Kw=[H+][OH-] = 1.0 x 10-14; [H+][8.9 x 10-12] = 1.0 x 10-14 ;[H+]=890;


pH=-log[890]=2.9]

Question 2
pts

Water is a unique molecule. Which of the following contributes to water’s unique place

,in the chemical world?

The geometry of the molecule
The polarity of the O-H bonds
The ability of water molecules to hydrogen bond
The bond angle of water
All of the answers are correct

ALL OF THE ANSWERS ARE CORRECT


What factor contributes to the bent shape of a water molecule?


The dipole arrows in a water molecule
The unshared electron pairs on the oxygen atom
The electronegativity difference between hydrogen and oxygen
The unequal electron sharing between hydrogen and oxygen
None of the answers are correct

THE UNSHARED ELECTRON PAIRS ON THE OXYGEN ATOM

Question 4
pts


Which diagrams correctly represent a hydrogen bond?

, A and B
A and D
B and C
C and D
A and C

A AND C


BOTH SHOW A PROTON DONOR AND ACCEPTOR

Question 5
pts


Scientific Calculator




The H+ concentration of a solution is 5.6 x 10-5 What is the pH?


-4.25
Correct!

4.25

[ [H+]=5.6 x 10-5; pH=-log[5.6 x 10-5]=4.25]

5.65
-9.75
9.75

4.25

[ [H+]=5.6 x 10-5; pH=-log[5.6 x 10-5]=4.25]


If the Ka of an acid is 2.67 x 10-5, what is the pKa?


7.45