Solutions

Q: In a solution, the substance that does the dissolving is called the ______, and the substance that gets dissolved is called the ______.

A: Solvent; Solute

Q: What do we call a solid solution that contains a mixture of metals?

A: An alloy

Q: Water is often referred to as the "________ solvent" because it is capable of dissolving more substances than any other liquid.

A: Universal

Q: A substance that can dissolve in a specific solvent is known as ______, while a substance that cannot dissolve is known as ______.

A: Soluble; Insoluble

Q: What is the standard unit of measurement for concentration in our class formula?

A: g/mL (grams per milliliter)

Q: When an environment is contaminated by harmful substances dissolved in water, we refer to these contaminants as ________.

A: Pollution

Q: A solution containing a large amount of solute particles is considered ________, while one with a small amount is considered ________.

A: Concentrated; Diluted

Q: True or False: Solid and gas solutions can only be formed if the substances involved are in the same state of matter.

True

Q: True or False: When you dissolve sugar into a glass of water, the overall volume of the water increases significantly.

A: False (The volume stays the same because the sugar particles fill the empty spaces between the water particles).

Q: True or False: If a solution is saturated, it means all the empty spaces between the solvent particles have been taken up by solute particles.

A: True

Q: True or False: Changing the temperature of a solution will change its current concentration.

A: False (At different temperatures, the current concentration does not change, but the solubility—how much more can dissolve—does change).

Q: Which of the following combinations can create a liquid solution?

Liquid + Solid, Liquid + Liquid, or Liquid + Gas

Q: Why does sugar NOT dissolve in oil?

The attraction between oil particles is stronger than the attraction between oil and sugar particles.

Q: If you add more solute to a solvent than it has the capacity to dissolve, what will happen?

It will not be able to dissolve all the solute.

Q: If a solvent is highly dense, what does that imply about its particles?

It has less empty space between its particles.

Q: To calculate how concentrated a solution is per 100mL, what mathematical step should you take after finding the base concentration (g/mL)?

Multiply by 100

According to the particle theory, why does the mass of a solution increase when sugar dissolves, even if the volume stays the same?

The sugar has mass. Even though the sugar particles hide in the empty spaces between the water particles (keeping volume the same), their mass is added to the water's mass.

Write out the formula used to calculate the concentration of a solution.

Concentration = mass of solute (in grams) / volume of solution (in mL)

Write out the formula used to calculate the solubility of a solution.

Solubility = maximum mass of solute that dissolves (in grams) / volume of solvent (in mL) at a certain temperature.

Based on your notes, what must be true about particle attraction for a solute to successfully dissolve in a solvent?

The attraction between the different particles (solute and solvent) must be stronger than the attraction between the similar particles (solute-to-solute or solvent-to-solvent).

Give an example of how water being a "universal solvent" can be both helpful and harmful to the environment.

Helpful: It dissolves essential minerals and nutrients for plants and animals. Harmful: It dissolves toxic chemicals/pesticides and carries them as pollution through ecosystems.

In high school chemistry, you will learn a rule called "like dissolves like." Water is a polar molecule (meaning it has slightly charged ends, like a magnet). Oil is a non-polar molecule. Using your knowledge of particle attraction, explain why water easily dissolves salt (which is made of charged ions), but absolutely refuses to dissolve oil.

For dissolving to happen, the attraction between the solvent and solute must be very strong. Because water is polar (charged) and salt is made of charged ions, they are highly attracted to each other ("like dissolves like"). Oil is non-polar (no charge), so the strong water-water attractions push the oil away rather than bonding with it.

Your notes state that temperature affects solubility. For solids like sugar, heating the water increases solubility. However, carbon dioxide is a gas dissolved in soda. If you leave a soda out in the hot sun, it goes "flat" very quickly. Using the particle theory of matter and kinetic energy, explain why heating a liquid decreases the solubility of a gas.

When a liquid is heated, its particles gain kinetic energy and move much faster. This rapid, violent movement breaks the attractive forces holding the gas particles in the "empty spaces" of the liquid, allowing the gas particles to escape into the air much faster than they would in a cold, slow-moving liquid.

At 20°C, the solubility of a specific chemical is 0.5 g/mL. A student currently has a solution at 20°C made by dissolving 30 grams of the chemical into 100 mL of water.
A) Is this current solution concentrated, dilute, saturated, or unsaturated?
B) Exactly how many more grams of the chemical could the student add before the solution reaches its absolute saturation point?

• A) It is unsaturated. (It is also concentrated, but "unsaturated" is the most scientifically accurate state because more can still dissolve).
  B) The student can add 20 more grams.
  Calculation step: The solubility is 0.5 g/mL. For 100 mL of solvent, the maximum mass it can hold is 0.5 x 100 = 50 grams. Since 30 grams are already dissolved, 50g - 30g = 20 grams of empty space remaining.