Mixtures and Solutions Practice Questions

Correct answer: Solvent

In a homogeneous solution, the solvent is the component present in the greater amount that dissolves the other substance. Water acts as the solvent because it dissolves the sodium chloride, which is the solute. Together, they form a uniform liquid mixture.

Correct answer: The composition and properties of the solution are uniform throughout its volume.

Homogeneous mixtures, or solutions, have a completely uniform distribution of particles down to the molecular level, so any sample drawn from the solution has identical composition and properties. Dissolved ions are far too small to scatter light, which is why a true solution shows no Tyndall effect; that scattering is the signature of a colloid, where the dispersed particles are much larger.

Correct answer: A suspension

A suspension is a heterogeneous mixture containing solid particles sufficiently large for sedimentation, meaning they will settle out over time if left undisturbed. Unlike solutions or colloids, the large particles in a suspension can also be separated from the liquid phase via mechanical filtration.

Correct answer: It is a colloid or fine suspension showing the Tyndall effect.

The scattering of light by microscopic particles in a mixture is known as the Tyndall effect, which is characteristic of colloids and suspensions. True solutions do not exhibit the Tyndall effect because their solute particles are individual molecules or ions, which are too small to scatter visible light waves.

Correct answer: Fractional distillation

Fractional distillation is an engineering and laboratory technique used to separate miscible liquids with different boiling points. As the mixture is heated, the component with the lower boiling point vaporizes first, travels up a fractionating column, and is cooled back into a liquid state in a condenser. This allows for efficient separation that simple filtration or centrifugation cannot achieve.

Correct answer: Like dissolves like

The rule of thumb 'like dissolves like' indicates that substances with similar intermolecular forces tend to be soluble in one another. Iodine and hexane are both nonpolar substances, allowing them to form stable solutions together, whereas water is a highly polar solvent that cannot effectively interact with nonpolar iodine molecules.

Correct answer: Supersaturated

A supersaturated solution contains more dissolved solute than a saturated solution could normally hold at that specific temperature. These mixtures are unstable and can be triggered to rapidly crystallize if a 'seed crystal' is added or if the container is mechanically agitated.

Correct answer: It increases the solubility of most solids but decreases the solubility of gases.

For most solid solutes, higher temperatures provide thermal energy that helps break down crystal lattices, increasing solubility. Conversely, raising the temperature adds kinetic energy to dissolved gas molecules, allowing them to overcome intermolecular attractions with the solvent and escape from the liquid phase into the air.

Correct answer: Henry's Law

Henry's Law states that at a constant temperature, the amount of a given gas dissolved in a given type and volume of liquid is directly proportional to the partial pressure of that gas in equilibrium with the liquid. When a soda bottle is opened, the pressure drops, causing the solubility of carbon dioxide to decrease rapidly, which results in the formation of gas bubbles.

Correct answer: A homogeneous solid solution

Alloys like stainless steel are homogeneous mixtures of metals, or metals mixed with other elements, structurally arranged down to an atomic level. Because the components are uniformly distributed and maintain a single phase in the solid state, they are classified as solid solutions.

Correct answer: 2.0 M

Molarity is defined mathematically as the number of moles of solute divided by the total volume of the resulting solution in liters. Dividing 2.0 moles of sucrose by 1.0 liter of solution yields a concentration of 2.0 M (moles per liter).

Correct answer: 50 mL

Using the dilution equation $M_1V_1 = M_2V_2$, where $M_1 = 1.0\text{ M}$, $M_2 = 0.10\text{ M}$, and $V_2 = 500\text{ mL}$, we can isolate the required volume of stock solution ($V_1$). Calculating $(0.10\text{ M} \times 500\text{ mL}) / 1.0\text{ M}$ results in $50\text{ mL}$ of the stock solution.

Correct answer: Boiling point elevation

Colligative properties depend exclusively on the total number of dissolved solute particles present in a given volume of solvent, rather than the chemical identity or nature of those particles. Boiling point elevation, freezing point depression, vapor pressure lowering, and osmotic pressure are the primary examples of colligative properties.

Correct answer: The salt particles disrupt the ordered structure needed to form an ice lattice.

When a solute dissolves, its particles physically occupy space between the solvent molecules and interfere with the highly structured, repeating crystalline arrangement that water must adopt in order to freeze. A lower temperature is therefore needed before ice can form, which is why freezing point depression is a colligative property that depends on the number of dissolved particles rather than their identity.

Correct answer: Solution B will have a higher boiling point than Solution A.

Sodium chloride ($NaCl$) is an electrolyte that dissociates into two distinct ions ($Na^+$ and $Cl^-$) per formula unit in water, whereas glucose is a nonelectrolyte that remains as single molecules. Because colligative properties like boiling point elevation depend on the total concentration of particles, the higher particle count in Solution B causes a greater boiling point elevation.

Correct answer: A colloid

An emulsion is a specific type of colloid formed by dispersing microscopic droplets of one liquid throughout another immiscible liquid. Because the dispersed particles are small enough to remain suspended without settling out, yet large enough to scatter light, it meets the structural definitions of a colloid.

Correct answer: Dialysis

Dialysis is a separation process that uses a semipermeable membrane to selectively filter out solute molecules based on their physical sizes. It is widely used in medicine to cleanse the blood of patients with kidney failure and in biochemistry to purify macromolecular mixtures.

Correct answer: Atmospheric air

Clean atmospheric air is a homogeneous gas solution composed primarily of nitrogen gas acting as the solvent, with oxygen, argon, carbon dioxide, and trace gases acting as the solutes. Fog and smoke are not true gas solutions; fog is a liquid-in-gas colloid, and smoke is a solid-in-gas colloid.

Correct answer: Chromatography

Chromatography encompasses a suite of techniques used to separate mixtures based on how individual components partition themselves between a stationary phase and a moving mobile phase. Components that interact strongly with the mobile phase move faster, while those that stick to the stationary phase move slower, separating the mixtures over time.

Correct answer: A heterogeneous suspension

Calcium carbonate is largely insoluble in water, and its large particles create a cloudy, non-uniform distribution when shaken. Because these large particles are visible to the naked eye and separate out due to gravity shortly after mixing, the mixture is characterized as a heterogeneous suspension.