Yes, chalk powder in water is a suspension.
Understanding Suspensions
A suspension is a type of heterogeneous mixture where solid particles are dispersed throughout a liquid medium but do not dissolve. The reference confirms this: "Because chalk powder is only slightly soluble in water, it will produce a suspension. A suspension is a liquid-solid solution in which the solid floats around in the liquid rather than dissolving in it."
In the case of chalk powder (primarily calcium carbonate, CaCO₃) and water, the tiny solid particles of chalk are too large to dissolve completely. Instead, they remain dispersed within the water, creating a cloudy mixture.
Characteristics of a Suspension
Suspensions have distinct characteristics that differentiate them from solutions or colloids:
- Heterogeneous: The composition is not uniform throughout the mixture. You can often see distinct solid particles.
- Particles Settle: If left undisturbed, the solid particles will eventually settle at the bottom due to gravity. This is a key difference from solutions.
- Particles are Visible: The solid particles in a suspension are large enough to be seen with the naked eye or a simple microscope.
- Scatters Light: Suspensions can scatter a beam of light passing through them (Tyndall effect), although this is also a property of colloids. However, unlike colloids, the particles are much larger and unstable over time.
- Can be Separated: The solid and liquid phases can be easily separated by simple physical methods like filtration or decantation (carefully pouring off the liquid).
Comparing Mixture Types
Here's a simple comparison of common mixture types:
| Mixture Type | Description | Particle Size | Stability (Settling) | Light Scattering (Tyndall) | Example |
|---|---|---|---|---|---|
| Solution | Homogeneous, solute dissolves in solvent | Very small (<1 nm) | Stable (No settling) | No | Saltwater, Sugar water |
| Colloid | Heterogeneous, particles dispersed but don't settle | Medium (1-1000 nm) | Stable (No settling) | Yes | Milk, Fog |
| Suspension | Heterogeneous, particles dispersed, will settle | Large (>1000 nm) | Unstable (Settles) | Yes | Chalk in water, Muddy water |
As the table shows, chalk powder in water fits the description and behavior of a suspension because the chalk particles don't dissolve and will settle over time.
Practical Examples
You encounter suspensions frequently in daily life:
- Muddy Water: Soil particles suspended in water.
- Some Medicines: Liquid antacids often contain suspended solid particles that need to be shaken before use.
- Orange Juice with Pulp: The pulp is suspended in the juice.
- Paint: Pigment particles suspended in a liquid medium.
In summary, the slight solubility of chalk in water results in undissolved chalk particles remaining dispersed, making the mixture a suspension.
