Physical Science Ch.8 Semester 2 Exam Review

1.

Why is water called the universal solvent?

Explanation
Water is called the universal solvent because it has the ability to dissolve a wide range of substances. This is due to its unique molecular structure, which allows it to form hydrogen bonds with other molecules. These hydrogen bonds break apart the solute molecules and surround them with water molecules, effectively dispersing them throughout the solution. Water's polarity and high dielectric constant also contribute to its solvent properties. As a result, water can dissolve various types of compounds, including polar and ionic substances, making it a versatile solvent in many chemical and biological processes.

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2.

What do substances dissolve?

Explanation
This answer is based on the principle that substances with similar chemical properties tend to dissolve in each other. In other words, polar substances dissolve in polar solvents, and nonpolar substances dissolve in nonpolar solvents. This is because the intermolecular forces between the solute and solvent molecules are similar, allowing them to mix and form a homogeneous solution. For example, water (a polar solvent) can dissolve salt (a polar solute) because both have polar molecules. Conversely, oil (a nonpolar solvent) can dissolve grease (a nonpolar solute) because both have nonpolar molecules.

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3.

Water is...?

A.

Polar
B.

Nonpolar
C.

Both

Correct Answer
C. Both

Explanation
Water is both polar and nonpolar. This is because water molecules have a polar nature due to the presence of polar covalent bonds between the oxygen and hydrogen atoms. The oxygen atom is more electronegative than the hydrogen atoms, causing a partial negative charge on the oxygen and partial positive charges on the hydrogen atoms. However, water also exhibits nonpolar characteristics due to its symmetrical bent molecular structure. The polarity of water allows it to form hydrogen bonds with other polar molecules or ions, while its nonpolar properties enable it to dissolve nonpolar substances like oils.

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4.

What is solubility?

Correct Answer
the maximum mass of a solute that can dissolve in 100 grams of solvent at a certain temperature and standard atmospheric pressure

Explanation
Solubility refers to the maximum amount of a solute that can dissolve in a given amount of solvent at a specific temperature and standard atmospheric pressure. It is a measure of the solute's ability to dissolve in the solvent. The answer accurately defines solubility as the maximum mass of a solute that can dissolve in 100 grams of solvent, providing a clear understanding of the concept.

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5.

What happens when when you add more solute to a saturated solution?

Correct Answer
It becomes super saturated

Explanation
When more solute is added to a saturated solution, it becomes super saturated. This means that the solution now contains more solute than it can normally hold at that temperature. The excess solute remains dissolved in the solution, creating an unstable state. Any disturbance, such as temperature change or the introduction of a seed crystal, can cause the excess solute to precipitate out of the solution, returning it to a saturated state.

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6.

How do you describe how much solute is in a solution?

Correct Answer
Saturated, unsaturated, supersaturated

Explanation
The correct answer is saturated, unsaturated, and supersaturated. These terms are used to describe the concentration of solute in a solution. A saturated solution contains the maximum amount of solute that can dissolve at a given temperature. An unsaturated solution has not reached its maximum solute capacity and can dissolve more solute. A supersaturated solution contains more solute than it should be able to hold at that temperature, often achieved through a process of heating and cooling.

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