Problem 102 - Introductory Chemistry Atoms First

Question

Name the acid and base that combine to form: (a) \(\mathrm{KNO}_{3}\) (b) \(\mathrm{Ca}_{3}\left(\mathrm{PO}_{4}\right)_{2}\) (c) \(\mathrm{Li}_{2} \mathrm{SO}_{4}\) (d) NaI

Step-by-Step Solution

Answer

(a) The acid and base that combine to form \(\mathrm{KNO}_{3}\) are nitric acid (HNO\(_{3}\)) and potassium hydroxide (KOH). (b) The acid and base that combine to form \(\mathrm{Ca}_{3}\left(\mathrm{PO}_{4}\right)_{2}\) are phosphoric acid (H\(_{3}\)PO\(_{4}\)) and calcium hydroxide (Ca(OH)\(_{2}\)). (c) The acid and base that combine to form \(\mathrm{Li}_{2} \mathrm{SO}_{4}\) are sulfuric acid (H\(_{2}\)SO\(_{4}\)) and lithium hydroxide (LiOH). (d) The acid and base that combine to form NaI are hydroiodic acid (HI) and sodium hydroxide (NaOH).

Step 1: (a) Identify the ions in \(\mathrm{KNO}_{3}\)

We can see that the given salt is composed of potassium (K\(^+\)) and nitrate (NO\(_{3}^-\)) ions. Now, we will identify the acid and base from which these ions come.

Step 2: (a) Determine the acid and base of \(\mathrm{KNO}_{3}\)

Potassium ion (K\(^+\)) comes from potassium hydroxide (KOH), which is a base. The nitrate ion (NO\(_{3}^-\)) comes from nitric acid (HNO\(_{3}\)), which is an acid. So, for \(\mathrm{KNO}_{3}\), the acid is nitric acid and the base is potassium hydroxide.

Step 3: (b) Identify the ions in \(\mathrm{Ca}_{3}\left(\mathrm{PO}_{4}\right)_{2}\)

In this salt, we have calcium (Ca\(^{2+}\)) and phosphate (PO\(_{4}^{3-}\)) ions. Now we will identify their corresponding acid and base.

Step 4: (b) Determine the acid and base of \(\mathrm{Ca}_{3}\left(\mathrm{PO}_{4}\right)_{2}\)

Calcium ion (Ca\(^{2+}\)) comes from calcium hydroxide (Ca(OH)\(_{2}\)), which is a base. The phosphate ion (PO\(_{4}^{3-}\)) comes from phosphoric acid (H\(_{3}\)PO\(_{4}\)), which is an acid. So, for \(\mathrm{Ca}_{3}\left(\mathrm{PO}_{4}\right)_{2}\), the acid is phosphoric acid and the base is calcium hydroxide.

Step 5: (c) Identify the ions in \(\mathrm{Li}_{2} \mathrm{SO}_{4}\)

In this salt, we have lithium (Li\(^+\)) and sulfate (SO\(_{4}^{2-}\)) ions. Now we will identify their corresponding acid and base.

Step 6: (c) Determine the acid and base of \(\mathrm{Li}_{2} \mathrm{SO}_{4}\)

Lithium ion (Li\(^+\)) comes from lithium hydroxide (LiOH), which is a base. The sulfate ion (SO\(_{4}^{2-}\)) comes from sulfuric acid (H\(_{2}\)SO\(_{4}\)), which is an acid. So, for \(\mathrm{Li}_{2} \mathrm{SO}_{4}\), the acid is sulfuric acid and the base is lithium hydroxide.

Step 7: (d) Identify the ions in NaI

In this salt, we have sodium (Na\(^+\)) and iodide (I\(^-\)) ions. Now we will identify their corresponding acid and base.

Step 8: (d) Determine the acid and base of NaI

Sodium ion (Na\(^+\)) comes from sodium hydroxide (NaOH), which is a base. The iodide ion (I\(^-\)) comes from hydroiodic acid (HI), which is an acid. So, for NaI, the acid is hydroiodic acid and the base is sodium hydroxide.

Key Concepts

Chemical Salts

Chemical salts are fascinating compounds formed from acid-base reactions. These reactions typically result when acids and bases neutralize each other. When an acid reacts with a base, the hydrogen ion (H extsuperscript{+}) from the acid combines with the hydroxide ion (OH extsuperscript{-}) from the base to form water. What remains are the salt's ions, which make up the resulting chemical salt.

Here are some key points about chemical salts:

• They consist of cations (positively charged ions) and anions (negatively charged ions).
• The properties of salts vary widely based on the ions present.
• Salts can be soluble or insoluble in water, affecting their uses and behavior.

Understanding the formation and properties of chemical salts is crucial to mastering concepts in chemistry, such as acid-base reactions in various environments.

Ion Identification

Ion identification is a fundamental concept in understanding how salts form. Each salt is made up of cations and anions that originate from specific acids and bases.

Here’s how you can identify ions in a salt:

• Look at the chemical formula. For example, in KNO extsubscript{3}, the cation is K extsuperscript{+} (potassium) and the anion is NO extsubscript{3} extsuperscript{-} (nitrate).
• Break down the formula to see individual elements and their charges.
• Use periodic tables or chemical resources to verify ions.

Knowing how to identify ions helps you trace them back to their parent acids and bases, providing more insight into the root of the chemical reaction.

Acid Identification

Acid identification involves tracing anions in salts back to their original acids. Acids are substances that donate hydrogen ions (H extsuperscript{+}) in water. When neutralizing bases, they pair with anions to form different salts.

To identify the acid in a salt:

• Look at the anion. For example, in KNO extsubscript{3}, NO extsubscript{3} extsuperscript{-} comes from nitric acid (HNO extsubscript{3}).
• Match the anion to known acids using chemistry databases.

Recognizing acids derived from salts gives clues to reaction processes and potential properties.

Base Identification

Just as with acids, identifying the base from which a salt is derived involves considering the cation. Bases are substances that provide hydroxide ions (OH extsuperscript{-}) in a solution. They often pair with cations to neutralize acids and form salts.

To identify the base in a salt:

• Focus on the cation. In Ca extsubscript{3}(PO extsubscript{4}) extsubscript{2}, Ca extsuperscript{2+} arises from calcium hydroxide (Ca(OH) extsubscript{2}).
• Match the cation with known bases for confirmation.

Understanding base identification helps chemists predict the outcomes of neutralization reactions and the resulting salts' characteristics.