Last modified: Sun 01/17/2016 03:30:35 pm
BCE

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Answer all of the questions below. If you do not know an answer enter CNA. However, it will help me the most if you answer each question with your best intuition/idea about what would be a reasonable answer.

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1. Salts are formed when an acid reacts with a base. For example the salt, NaCl is formed in the neutralization reaction when the acid HCl (a strong acid) reacts with the base NaOH (a strong base);

HCl(aq) + NaOH(aq) ----> NaCl(aq) + H2O(l)

The three substances listed in the table below are salts. For each salt identify the formula of the acid and base that must react to form the salt and indicate if the acid is strong or weak and if the base is strong or weak.

KBr

The acid is

Strong/Weak

The base is

Strong/Weak

NaCN

The acid is

Strong/Weak

The base is

Strong/Weak

NH4NO3

The acid is

Strong/Weak

The base is

Strong/Weak

2. The pH of 0.100 M solutions of each of the salts above is measured and recorded below. Identify whether the salt is behaving like an acid or a base when dissolved in water. NOTE: Use the pH measurement of each salt solution to identify the acid/base properties of each salt in the text field in the table. (i.e, is the salt an acid or a base?)

Salt (0.1M)

pH

Is the salt behaving like an acid or a base?

KBr

7.00

NaCN

11.1

NH4NO3

 

2.87

3. Based on these three salts consider the acid and base that reacted to form the salt. State a general rule for the acid/base properties of salts based on the strength of the acid and base (strong/weak) that reacted to form the salt.

a) a salt formed by a strong acid and a strong base is (acid, base or neutral)

b) a salt formed by a weak acid and a strong base is (acid, base or neutral)

c) a salt formed by a strong acid and a weak base is (acid, base or neutral)

4. Knowing the pH for the 0.100 M NaCN solution is 11.1, calculate the [OH-] in the solution.

[OH-] = M

5. Knowing the pH for the 0.100 M NH4NO3 solution is 2.87, calculate the [H+] in the solution.

[H+] = M

6. Is there anything about the questions that you feel you do not understand? List your concerns/questions.

7. If there is one question you would like to have answered in lecture, what would that question be?