Question

Name these hydrates: (a) \(\mathrm{BaBr}_{2} \cdot 2 \mathrm{H}_{2} \mathrm{O}\) (b) \(\mathrm{AlCl}_{3} \cdot 6 \mathrm{H}_{2} \mathrm{O}\) (c) \(\mathrm{FePO}_{4} \cdot 4 \mathrm{H}_{2} \mathrm{O}\)

Short answer

a) Barium Bromide Dihydrate, b) Aluminum Chloride Hexahydrate, c) Iron(III) Phosphate Tetrahydrate

Step-by-step solution

Identify the ionic compound

First, identify the base ionic compound in each hydrate formula before the dot (\(\cdot\)). For (a): \(\mathrm{BaBr}_{2}\), for (b): \(\mathrm{AlCl}_{3}\), and for (c): \(\mathrm{FePO}_{4}\).

Name the ionic compound

Now name the ionic compounds identified. For (a): Barium Bromide, for (b): Aluminum Chloride, and for (c): Iron(III) Phosphate (since \(\mathrm{Fe}\) has a +3 charge).

Identify the number of water molecules

Identify the number of water molecules attached in each hydrate. For (a): 2, for (b): 6, and for (c): 4.

Name the water molecules as 'hydrate'

Using prefixes for the number of water molecules, name them as 'hydrate'. For (2): 'dihydrate', for (6): 'hexahydrate', and for (4): 'tetrahydrate'.

Combine the names

Combine the name of the ionic compound with the prefix-hydrate term. For (a): Barium Bromide Dihydrate, for (b): Aluminum Chloride Hexahydrate, and for (c): Iron(III) Phosphate Tetrahydrate.

Key concepts

ionic compounds

Ionic compounds are made up of positively and negatively charged ions. These ions are held together by strong electrostatic forces, known as ionic bonds. In the exercise, the compounds \(\text{BaBr}_2\), \(\text{AlCl}_3\), and \(\text{FePO}_4\) are ionic compounds.

An ionic compound is usually made between a metal and a non-metal. For example: \(\text{BaBr}_2\) consists of barium (a metal) and bromine (a non-metal). The metal loses electrons to become a positively charged cation, while the non-metal gains electrons to become a negatively charged anion.

Understanding ionic compounds is essential because these compounds form unique structures and play significant roles in both chemistry and everyday life.

chemical nomenclature

Chemical nomenclature is the systematic method used for naming chemical substances. This ensures that every compound's name clearly describes its chemical composition and structure.

For ionic compounds, the name typically consists of the cation name followed by the anion name. For metals that can have different charges (like iron), we specify the charge using Roman numerals. In our examples, \(\text{BaBr}_2\) is named Barium Bromide and \(\text{AlCl}_3\) is named Aluminum Chloride. For \(\text{FePO}_4\), we use the name Iron(III) Phosphate because iron in this compound has a +3 charge.

This systematic approach helps avoid confusion, ensuring that each compound is uniquely and consistently identified.

hydrates

Hydrates are compounds that include water molecules within their crystalline structure. These water molecules are not just physically trapped but are chemically bonded within the compound. In the given exercise, the chemical formulas provided each have \text{H}_2O\ molecules attached with a dot before the water part.

To name hydrates, first, you name the base ionic compound, and then you use prefixes to denote the number of water molecules attached. For example:

• \(\text{BaBr}_2 \cdot 2 \text{H}_2 \text{O}\) becomes Barium Bromide Dihydrate (di- meaning 2).
• \(\text{AlCl}_3 \cdot 6 \text{H}_2 \text{O}\) becomes Aluminum Chloride Hexahydrate (hexa- meaning 6).
• \(\text{FePO}_4 \cdot 4 \text{H}_2 \text{O}\) becomes Iron(III) Phosphate Tetrahydrate (tetra- meaning 4).

Understanding how to properly name hydrates is crucial for correctly communicating the composition of these compounds.