Write the equation when solid chromium (II) bromide is put into water.
The correct answer and explanation is:
When solid chromium(II) bromide (CrBr₂) is placed into water, it dissociates into its ions. The dissociation reaction is represented by the following equation:
CrBr2(s)→Cr2+(aq)+2Br−(aq)\text{CrBr}_2 (s) \rightarrow \text{Cr}^{2+} (aq) + 2\text{Br}^- (aq)
Explanation:
Chromium(II) bromide, CrBr₂, is an ionic compound that consists of chromium ions (Cr²⁺) and bromide ions (Br⁻). When CrBr₂ is added to water, the ionic compound dissolves in the solvent due to the polar nature of water molecules. Water molecules surround and stabilize the ions, causing them to separate from the solid and move freely in the aqueous solution. This process is called dissociation.
- Chromium Ion (Cr²⁺): Chromium(II) has a 2+ charge, and in the aqueous solution, it exists as the Cr²⁺ ion. The chromium ion is stabilized by the water molecules’ partial negative charge, which is attracted to the positively charged Cr²⁺ ions.
- Bromide Ion (Br⁻): The bromide ion (Br⁻) is a negatively charged ion. Each bromide ion is surrounded by water molecules with their partial positive hydrogen atoms oriented towards the negative bromide ions. The interaction between water molecules and ions helps keep the ions in the dissolved state.
The dissociation of CrBr₂ in water is an example of a typical ionic compound dissolving in water to form a solution of free-moving ions. The process is endothermic in nature, meaning it absorbs heat from the surroundings as the solid dissolves.
In summary, the solid CrBr₂ breaks apart into chromium(II) ions and bromide ions when placed in water, with the ions being surrounded by water molecules, creating an aqueous solution.