Mixtures, Solutions, and Solubility Unit Test Review

Questions and Answers

What happens to water when it freezes?

Its density decreases.

What should the mixture shown in the picture be classified as?

suspension

Which contributes to the polarity of a water molecule?

deflection of hydrogen atoms by lone pairs of electrons

Which is true about the dissolving process in water?

Water molecules are attracted by solute ions at the surface of the solute. Signup and view all the answers

Which factor causes a decrease in the rate of dissolution?

decreasing the surface area of the solute Signup and view all the answers

Which statements are true of heterogeneous mixtures? (Select all that apply)

The proportions of solute to solvent may vary. Signup and view all the answers

What type of mixture scatters light and cannot be filtered easily?

a colloid, a heterogeneous mixture Signup and view all the answers

Which describes a property of water that allows plants to transfer it from their roots to their leaves?

Water exhibits strong adhesion and cohesion, which allows capillary action to occur. Signup and view all the answers

What is the name of a solution whose concentration of solute is equal to the maximum concentration that is predicted from the solute's solubility?

saturated Signup and view all the answers

Which sample most likely had the lowest solubility?

3 Signup and view all the answers

Which statement highlights a unique role of water in a biological system?

It provides organisms a medium to transport materials. Signup and view all the answers

Which heterogeneous mixture contains large particles that can settle out or can be filtered?

suspension Signup and view all the answers

Which statement best describes the formation of a solution?

A small amount of solute is dissolved in a larger amount of solvent. Signup and view all the answers

A solid is stirred into a liquid and dissolves. What type of mixture forms?

a solution Signup and view all the answers

Which is true about dissolving a polar substance in water?

The solute particles are carried into the solution. Signup and view all the answers

Which method would increase the solubility of a gas?

increasing the pressure Signup and view all the answers

What is a cause of polarity in water molecules?

high electronegativity difference between oxygen and hydrogen Signup and view all the answers

Water can resist a greater external force than ethanol can. Which statement best describes this difference?

Water has greater surface tension than ethanol. Signup and view all the answers

Which solution is a homogeneous mixture?

salt and water Signup and view all the answers

Which is the best example of water regulating an organism's body temperature?

a jogger sweating after a run Signup and view all the answers

Which statement would be true about a water molecule if it had a linear shape?

It would be a nonpolar molecule. Signup and view all the answers

In which situation can a mixture always be called a solution?

when the mixture is homogeneous Signup and view all the answers

Which is a characteristic of a homogeneous mixture that is a liquid?

It cannot be separated using filtration. Signup and view all the answers

Which best explains why blood and the cytoplasm of cells are mainly composed of liquid water?

Water is an important transport and reaction medium. Signup and view all the answers

The concentration of a solute in a solution is greater than the maximum concentration that is predicted from the solute's solubility. What is the best way to describe this solution?

supersaturated Signup and view all the answers

Which is an example of a nonaqueous solution?

gasoline Signup and view all the answers

Which describes the polarity in a water molecule?

partial negative charge on the oxygen atom because it pulls electrons from the hydrogen atoms. Signup and view all the answers

Which ingredient in a can of soda is the solvent?

water Signup and view all the answers

Which factor influences both solubility and the rate of dissolution?

temperature Signup and view all the answers

Which is most likely true about water in chemical systems?

Water dissociates ionic compounds. Signup and view all the answers

Brownian motion is not observed in a mixture that includes two phases. Which best identifies the mixture?

a suspension Signup and view all the answers

Which statement accurately describes part of the dissolving process of a polar solute in water?

Water molecules surround solute molecules. Signup and view all the answers

Which factors will cause a solid solute to dissolve faster?

increasing the surface area of solute Signup and view all the answers

Which best explains why water has a much higher boiling point than would otherwise be predicted?

Water forms strong hydrogen bonds. Signup and view all the answers

Which is the solvent in a solution containing 90 mL of methanol, 18 mL of propanol, and 2 mL of diethyl ether?

methanol Signup and view all the answers

How many grams of NaCl will be needed to form 600 mL of a saturated solution at 100°C?

240 g Signup and view all the answers

Water is called the 'universal solvent.' Which statement best explains this description with respect to ionic compounds?

Water can dissociate many ionic compounds through ion-dipole interactions. Signup and view all the answers

Study Notes

Mixtures and Solutions Overview

Water expands and decreases in density when it freezes, making ice less dense than liquid water.
Mixtures stirred for a brief period may form suspensions, which are heterogeneous and can settle over time.

Properties of Water

The polarity of a water molecule is affected by the arrangement of hydrogen atoms and lone pairs of electrons on oxygen.
Water molecules are attracted to solute ions at the surface during the dissolution process, facilitating the mixing of solutes and solvents.

Factors Influencing Dissolution

Decreasing the surface area of the solute reduces the rate of dissolution.
Increasing pressure enhances the solubility of gases, allowing more gas to be dissolved in liquids.

Mixture Classifications

Heterogeneous mixtures, like suspensions and colloids, contain unevenly distributed components, with larger particles capable of settling or being filtered.
Homogeneous mixtures, such as solutions, have uniform composition and cannot be separated by filtration.

Solution Dynamics

A saturated solution contains the maximum concentration of solute possible at a given temperature.
When a solute concentration exceeds its solubility, it is classified as supersaturated.

Biological Significance of Water

Water's unique properties, such as adhesion, cohesion, and high surface tension, make it crucial for transporting nutrients and regulating organism temperature.
Brownian motion, a sign of suspension stability, is absent in mixtures with distinct phases, indicating a lack of continuous particle movement.

Hydrogen Bonding and Polarity

Hydrogen bonds in water contribute to its higher than expected boiling point, reflecting strong intermolecular interactions.
Water’s structure results in a partial negative charge on oxygen and a positive charge on hydrogen, making it a polar molecule. A linear water molecule would be nonpolar instead.

Solubility and Temperature

Temperature significantly influences both the solubility of substances and the rate at which solutes dissolve.
Increased solute surface area can lead to faster dissolution rates.

Solute-Solvent Relationships

In solutions, the solute is usually in smaller amounts compared to the solvent, which forms the medium of the solution.
Water's ability to dissociate ionic compounds demonstrates its role as the "universal solvent" through ion-dipole interactions.

Experimental Observations

The amount of NaCl required for a saturated solution at high temperature, such as 100°C, illustrates how temperature affects solubility, requiring significant amounts like 240 g for a specific volume.
The examples highlight the composition of various solutions, where methanol serves as a solvent in mixtures containing other alcohols and ethers.

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Prepare for your test on mixtures, solutions, and solubility with this comprehensive review. The flashcards cover key concepts, including the characteristics of water, classification of mixtures, and molecular polarity. Enhance your understanding and boost your confidence for the upcoming exam.