Question

Explain how anhydrous copper(II) sulfate \(\left(\mathrm{CuSO}_{4}\right)\) can act as an indicator for moisture.

Short answer

Anhydrous \(\text{CuSO}_{4}\) turns blue upon contact with water, indicating presence of moisture.

Step-by-step solution

- Understand Anhydrous Copper(II) Sulfate

Anhydrous copper(II) sulfate \(\text{CuSO}_{4}\) is a chemical compound in its dry form. It is a white powder.

- Reaction with Water

When anhydrous copper(II) sulfate comes in contact with water, it undergoes a reaction to form hydrated copper(II) sulfate \(\text{CuSO}_{4} \bullet 5\text{H}_2\text{O}\). This compound is blue in color.

- Color Change as Indicator

Due to this reaction, the color change from white (anhydrous) to blue (hydrated) serves as an indicator for the presence of moisture. If moisture is present, the white anhydrous copper(II) sulfate will turn blue.

Key concepts

hydration reaction

A hydration reaction occurs when a substance combines with water to form a new compound. In the case of anhydrous copper(II) sulfate, \(\text{CuSO}_{4}\), the substance starts off as a white powder. When it comes in contact with water, it undergoes a hydration reaction, forming a blue compound known as hydrated copper(II) sulfate, or \(\text{CuSO}_{4} \bullet 5\text{H}_2\text{O}\). This process is a clear demonstration of a chemical change.

During the hydration reaction, water molecules attach themselves to the copper sulfate particles. This attachment leads to a change in both the chemical structure and physical properties of the compound.

The reaction can be summarized by the chemical equation:

\[\text{CuSO}_{4} + 5\text{H}_2\text{O} \rightarrow \text{CuSO}_{4} \bullet 5\text{H}_2\text{O}\]

Note that during hydration reactions like this, a significant visual change often occurs, making them easy to observe.

color change indicators

Color change indicators are substances that exhibit a change in color when they undergo a chemical or physical change. Anhydrous copper(II) sulfate serves as a color change indicator for moisture. Initially, it is white in its dry form. Upon exposure to water, it transforms into its hydrated form, which is blue.

To explain this visually, think of starting with a container of white powder. If you add water and the powder turns blue, you've got a handy color change indicator!

Different substances can serve as color change indicators. These are often used in chemical experiments to show the completion of reactions or to indicate the presence of specific substances. In the case of copper sulfate:

• When dry: White color (Anhydrous).
• When hydrated: Blue color.

This clear visual cue helps in quickly identifying the presence of moisture in various settings.

chemical compounds

Chemical compounds are substances made up of two or more different elements that are chemically bonded together. Copper(II) sulfate is a great example to understand this concept. It consists of copper (Cu), sulfur (S), and oxygen (O). In its anhydrous form, it is represented by \(\text{CuSO}_{4}\)

When we talk about chemical compounds, we often consider:

• Their physical state (solid, liquid, gas).
• Color.
• Chemical properties, such as reactivity with water.

Copper(II) sulfate changes its properties significantly when it transitions from an anhydrous to a hydrated state by absorbing water. This is not just a physical but a chemical transformation involving new bonds and energy changes.

Chemical compounds like copper sulfate are used widely in science and industry due to their reactive properties. Understanding how they interact with other substances, like water, is fundamental in chemistry.