Acids and Bases (Worksheet)

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Work in groups on these problems. You should try to answer the questions without referring to your textbook. If you get stuck, try asking another group for help.

Q1.

Fill out the following table for each of the following chemical species. Indicate if the species would act as a Brønsted acid, base, or both. Then write the chemical formula for the conjugate acid and base of the species. If it has not conjugate acid, write none.

Chemical Species Acid, Base, Both, or Neither Conjugate Acid Conjugate Base
$$HI$$
$$NH_4^+$$
$$HClO_2$$
$$NO_2^‐$$
$$HPO_4^{2‐}$$
$$NH_2^‐$$

Q2.

Which solution has a higher pH?

1. A 0.1 M solution of an acid with $$K_a = 1 \times 10^{‐4}$$ or one with $$K_a = 4 \times 10^{‐5}$$
2. A 0.1 M solution of an acid with $$pK_a = 1.0$$ or one with $$pK_a = 3.5$$
3. A 0.1 M solution of a weak acid or a 0.01 M solution of the same acid.
4. A solution of pOH 6.0 or one of pOH 8.0.

Q3.

Calculate the pH and the pOH of 67.0 mL of a 0.0525 M solution of $$HNO_3$$.

Q4.

1. What are $$[H3O^+]$$, [OH‐], and pOH in a solution with a pH of 9.78?
2. What are $$[H3O^+]$$, [OH‐], and pOH in a solution with a pH of 3.47?

Q5.

How many moles of $$H3O^+$$ or OH‐ must you add per liter of HCl solution to adjust its pH form 3.25 to 3.65? Assume a negligible volume change.

Q6.

What is an amphoteric species? Name on e and write balanced equations that show why it is amphoteric.

Q7.

Choose the stronger acid in each of the following pairs:

1. $$H_2SeO_3$$ or $$H_2SeO_4$$
2. $$H_3PO_4$$ or $$H_3AsO_4$$
3. $$H_2S$$ or $$H_2Te$$

Q8.

Write balanced equations and Kb expressions for these Bronsted‐Lowry bases in water:

1. Pyridine, $$C_5H_5N$$
2. $$CO_2^{2‐}$$

Q9.

Calculate the pH of a 0.015 M solution of $$HCN$$. ($$K_a = 1.0 \times 10^{‐5}$$)

Q10.

What is the pH of a 0.200 M $$KNO_2$$ solution? ($$K_a = 5.1 \times 10^{‐4}$$)

Q11.

Explain with equations and calculations, when necessary, whether an aqueous solution of each of these salts is acidic, basic, or neutral:

1. $$KBr$$
2. $$NH_4I$$
3. $$KCN$$