Aqueous Solutions Quiz

1.

Why does water have unique characteristics compared to other similar molecules?

A.

Water molecules have strong intermolecular attractions.
B.

Water molecules have very high viscosity.
C.

Water molecules exist in aqueous solution.
D.

Water has a very low specific heat and is nonpolar.

Correct Answer
A. Water molecules have strong intermolecular attractions.

Explanation
Water molecules have strong intermolecular attractions due to hydrogen bonding. This occurs because water is a polar molecule, with oxygen being more electronegative than hydrogen. This creates a partial negative charge on the oxygen atom and partial positive charges on the hydrogen atoms. These opposite charges attract neighboring water molecules, resulting in hydrogen bonds. These strong intermolecular attractions give water unique characteristics such as high boiling and melting points, high surface tension, and the ability to dissolve many substances.

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2.

Many substances are soluble in water. Which property of water makes this possible?

A.

Water can dissolve a wide variety of substances
B.

Water has the ability to cleanse itself through the water cycle
C.

Water dissolves easily in the air, creating humidity
D.

Water is found in large quantities around the world

Correct Answer
A. Water can dissolve a wide variety of substances

Explanation
Water is able to dissolve a wide variety of substances due to its polarity and ability to form hydrogen bonds. Water molecules have a partial positive charge on the hydrogen atoms and a partial negative charge on the oxygen atom. This polarity allows water molecules to attract and surround other polar or charged molecules, breaking their bonds and causing them to dissolve. Additionally, water can also dissolve nonpolar substances through a process called dispersion, where water molecules cluster around nonpolar molecules and disperse them. Overall, water's ability to dissolve a wide variety of substances is due to its unique molecular structure and intermolecular forces.

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3.

The chemical equations for photosynthesis and respiration are provided: Photosynthesis: 6 CO2 + 6 H2O → C6H12O6 + 6 O2 Respiration: C6H12O6 + 6 O2 → 6 CO2 + 6 H2O Water is among the chemicals in both of these equations. Based on this information, why is it important that plants have water available in their environment?

A.

Plants need water for respiration as well as glucose.
B.

Plants need water in order to break down glucose for energy.
C.

Plants use water to create energy in the form of glucose.
D.

Plants clean water for other organisms in the environment.

Correct Answer
C. Plants use water to create energy in the form of glucose.

Explanation
Plants use water to create energy in the form of glucose. This is evident from the chemical equation for photosynthesis, where water (H2O) is one of the reactants that combines with carbon dioxide (CO2) to produce glucose (C6H12O6) and oxygen (O2). Water is a crucial component in the process of photosynthesis, allowing plants to convert sunlight into energy-rich glucose molecules. Therefore, it is important for plants to have water available in their environment to sustain their energy production and survival.

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4.

The different combinations of cations and anions created by the student is recorded in the data table shown. Which statement below best predicts the solubility of each combination in water?

A.

Combination #1 = soluble, Combination #2 = soluble
B.

Combination #1 = insoluble, Combination #2 = soluble
C.

Combination #1 = soluble, Combination #2 = insoluble
D.

Combination #1 = insoluble, Combination #2 = insoluble

Correct Answer
D. Combination #1 = insoluble, Combination #2 = insoluble

Explanation
The student recorded that both Combination #1 and Combination #2 are insoluble. This suggests that neither combination will dissolve in water.

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5.

Which statement below is generally true regarding factors that affect the solubility of solids in water?

A.

As the pressure increases, the solubility decreases.
B.

As the pressure increases, the solubility increases.
C.

Ions with greater charge are more soluble in water.
D.

Nonpolar solids are more soluble in water than polar solids.

Correct Answer
B. As the pressure increases, the solubility increases.

Explanation
As the pressure increases, the solubility increases. This is because an increase in pressure leads to an increase in the number of gas molecules in the solution. This increase in gas molecules increases the likelihood of collisions between the gas molecules and the solvent molecules, which in turn increases the rate of dissolution. Therefore, higher pressure generally leads to higher solubility of solids in water.

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6.

Water exhibits a unique property of surface tension. What happens among the water molecules to cause this property to occur?

A.

The water molecules begin to spread out rapidly near the surface of the water.
B.

The water molecules are nonpolar and repel each other near the surface of the water.
C.

The water molecules are strongly attracted to each other through hydrogen bonding.
D.

The water molecules do not move very quickly near the surface of the water.

Correct Answer
C. The water molecules are strongly attracted to each other through hydrogen bonding.

Explanation
Water exhibits surface tension because the water molecules are strongly attracted to each other through hydrogen bonding. Hydrogen bonds form between the positively charged hydrogen atoms of one water molecule and the negatively charged oxygen atoms of neighboring water molecules. This attraction creates a cohesive force that pulls the water molecules together, causing the surface of the water to behave like a stretched elastic sheet. This property allows certain insects, like water striders, to walk on water and droplets to form spherical shapes.

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