Question

Classify the following liquid mixtures as heterogeneous or homogeneous. Further classify each homogeneous mixture as a solution or colloid. (a) Orange juice with pulp (b) Apple juice (c) Hand lotion (d) Tea

Short answer

(a) Heterogeneous; (b) Homogeneous, Solution; (c) Homogeneous, Colloid; (d) Homogeneous, Solution.

Step-by-step solution

Understand the Problem

First, we need to classify each liquid mixture as either heterogeneous or homogeneous. A heterogeneous mixture has visibly different parts, while a homogeneous mixture appears uniform throughout.

Classify Orange Juice with Pulp

Orange juice with pulp contains solid bits suspended in the liquid. This mixture has visually distinct components and is not uniform throughout.

Conclusion for Orange Juice

Orange juice with pulp is a heterogeneous mixture.

Classify Apple Juice

Apple juice appears uniform and consistent throughout, with no visible distinct parts, giving it a homogeneous appearance.

Further Classification of Apple Juice

Since apple juice is homogeneous, we need to determine if it's a solution or colloid. Apple juice is a solution because it's a uniform mixture where the solute (sugar, flavor compounds) is fully dissolved in the solvent (water).

Classify Hand Lotion

Hand lotion appears uniform to the naked eye. It does not have visibly distinct parts and is consistent in its appearance.

Further Classification of Hand Lotion

Although hand lotion is homogeneous in appearance, it is not a solution but a colloid. Colloids have particles that are dispersed throughout the mixture and do not settle out.

Classify Tea

Tea is another mixture that appears consistent and uniform throughout, with no visible distinct parts, classifying it as homogeneous.

Further Classification of Tea

Tea is a solution because the solute (flavor compounds, color) is fully dissolved in the solvent (water).

Key concepts

Heterogeneous Mixtures

A heterogeneous mixture is a combination where the different components are distinguishable, either visually or through microscopic examination. In such mixtures, the elements remain separate entities. They do not form a uniform composition. A classic example is orange juice with pulp. The pulp particles create a visibly distinct phase from the liquid.
Unlike other mixture types, heterogeneous mixtures can have multiple phases that remain unblended. This means components, like the pulp in orange juice, can settle over time or require shaking to evenly distribute again.

• Observable different parts
• Components can settle
• Requires mixing for uniformity

Understanding this concept helps in identifying mixtures that do not blend completely and require occasional mixing to maintain a consistent appearance.

Homogeneous Mixtures

Homogeneous mixtures are mixtures that are uniform in composition and appearance. These mixtures do not show different phases or have visible distinct parts. A common example is apple juice or tea, both appear the same throughout the liquid.
These mixtures result from thorough mixing where one or more substances dissolve completely in another, resulting in a single-phase system. They are sometimes called solutions if they meet certain criteria, which we'll explore further.

• Uniform throughout
• No visible distinct parts
• Single-phase system

Homogeneous mixtures are typically difficult to separate by physical means due to their uniformity.

Solutions

Solutions are a type of homogeneous mixture where the solute is completely dissolved in the solvent, making them appear as one phase. Examples include apple juice and tea, where sugars, flavors, and other solutes are dissolved in water.
The defining feature of solutions is the complete integration of solute and solvent at a molecular level, ensuring no particles are left suspended.

• Complete dissolution of solute in solvent
• Uniform at the molecular level
• Stable solution without settling

Solutions are clear mixtures because the dissolved particles are too small to scatter light visibly.

Colloids

Colloids fall between homogeneous mixtures and heterogeneous mixtures. They have particles that are dispersed throughout but do not settle out like in a heterogeneous mixture. Hand lotion is a prime example of a colloid.
In colloids, the dispersed particles are larger than in solutions but still too small to settle out. These particles can scatter light, an effect known as the Tyndall effect, making colloids appear cloudy or opaque.

• Particles are dispersed but do not settle
• Exhibit Tyndall effect (light scattering)
• Appear uniformly mixed

Colloids maintain a stable form that doesn’t separate easily over time, distinguishing them from regular heterogeneous mixtures.