Q1. Fill in the formulas and names in the following table.

Background

Topic: Nomenclature of Ionic Compounds

This question tests your ability to write chemical formulas from compound names and vice versa, focusing on common ionic compounds and their systematic names.

Key Terms and Concepts:

• Cation: A positively charged ion (e.g., Na+, Ca2+).

• Anion: A negatively charged ion (e.g., Cl-, SO42-).

• Formula Writing: Combine cations and anions in ratios that balance the overall charge to zero.

• Naming: Name the cation first, then the anion (with appropriate suffixes such as -ide, -ate, -ite).

Step-by-Step Guidance

1. Identify the cation and anion for each compound. For example, in sodium chloride, sodium is the cation (Na+) and chloride is the anion (Cl-).

2. Write the correct chemical formula by balancing the charges. For instance, for calcium chloride, Ca2+ and Cl- combine in a 1:2 ratio to form CaCl2.

3. For compounds with polyatomic ions (e.g., sulfate SO42-), ensure the correct formula by balancing charges with the cation.

4. When given a formula, write the name by identifying the cation and anion and applying the correct naming conventions.

5. Continue this process for each row in the table, ensuring all charges are balanced and names are systematic.

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Q2. Fill in the formulas for the appropriate formula in the following table.

Background

Topic: Writing Ionic Formulas for Multivalent Ions

This question tests your ability to write correct formulas for compounds formed between given cations and anions, especially for ions with multiple possible charges.

Key Terms and Concepts:

• Multivalent Ions: Ions that can have more than one possible charge (e.g., Fe2+ and Fe3+).

• Formula Writing: Combine ions in ratios that balance the total positive and negative charges.

Step-by-Step Guidance

1. For each cell, identify the cation and anion and their charges.

2. Determine the ratio of ions needed to balance the charges to zero.

3. Write the chemical formula using subscripts to indicate the number of each ion.

4. Repeat for each combination in the table.

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Q3. 10.3 g of the hydrate of AlCl3 is analyzed and found to contain 2.73 g of water. What is the formula of the hydrate?

Background

Topic: Hydrates and Empirical Formulas

This question tests your ability to determine the formula of a hydrate by calculating the mole ratio of water to the anhydrous salt.

Key Terms and Formulas:

• Hydrate: A compound that contains water molecules within its crystal structure.

• Anhydrous Salt: The compound remaining after water is removed.

• Empirical Formula Calculation: Find moles of water and moles of anhydrous salt, then determine the simplest whole-number ratio.

• Molar Masses: Use the molar mass of H2O (18.02 g/mol) and AlCl3 (133.34 g/mol).

Step-by-Step Guidance

1. Calculate the mass of anhydrous AlCl3 by subtracting the mass of water from the total mass of the hydrate.

2. Convert the mass of water to moles using the molar mass of H2O.

3. Convert the mass of anhydrous AlCl3 to moles using its molar mass.

4. Set up the ratio of moles of water to moles of AlCl3.

5. Express the formula as AlCl3·xH2O, where x is the ratio you calculated.

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