Chemistry: Mixtures vs Solutions: Concentration and Saturation
Exploring solutes, solvents, concentration, and saturation
Chemistry: Mixtures vs Solutions: Concentration and Saturation
Exploring solutes, solvents, concentration, and saturation
Chemistry - Grade 6-8
- 1
Classify each example as a mixture or a solution: trail mix, salt water, muddy water, and lemonade with all sugar dissolved.
A solution is a type of mixture that looks the same throughout.
Trail mix and muddy water are mixtures because their parts are not evenly spread out. Salt water and lemonade with all sugar dissolved are solutions because the solute is evenly distributed in the solvent. - 2
In a cup of sugar water, identify the solute and the solvent.
The sugar is the solute because it is the substance being dissolved. The water is the solvent because it does the dissolving. - 3
A student dissolves 10 grams of salt in 100 milliliters of water. What is the concentration in grams per milliliter?
Use concentration equals amount of solute divided by amount of solvent or solution, depending on the units given.
The concentration is 0.1 grams per milliliter because 10 grams divided by 100 milliliters equals 0.1 grams per milliliter. - 4
Two cups contain the same amount of water. Cup A has 1 teaspoon of drink mix dissolved in it. Cup B has 3 teaspoons of drink mix dissolved in it. Which cup has the higher concentration? Explain.
Cup B has the higher concentration because it has more solute dissolved in the same amount of water. - 5
A solution contains 25 grams of sugar dissolved in 250 milliliters of water. A second solution contains 25 grams of sugar dissolved in 500 milliliters of water. Which solution is more dilute? Explain.
Dilute means less concentrated.
The second solution is more dilute because the same amount of sugar is spread through a larger amount of water. - 6
At room temperature, a glass of water can dissolve up to 36 grams of salt. If only 20 grams of salt are dissolved, is the solution saturated or unsaturated? Explain.
The solution is unsaturated because it can still dissolve more salt before reaching the maximum of 36 grams. - 7
At room temperature, a glass of water can dissolve up to 36 grams of salt. If 36 grams are dissolved and no more salt can dissolve, what type of solution is it?
A saturated solution cannot dissolve more solute under the same conditions.
It is a saturated solution because it contains the maximum amount of dissolved salt at that temperature. - 8
A student adds sugar to tea and sees sugar crystals sitting at the bottom after stirring for a long time. What does this show about the solution?
This shows that the solution is saturated, or possibly past its saturation point, because extra sugar is not dissolving and remains as crystals. - 9
Explain how temperature can affect how much solid solute, such as sugar, dissolves in water.
Think about why sugar often dissolves faster and in larger amounts in hot tea than in iced tea.
For many solid solutes, warmer water can dissolve more solute than colder water. Heating the water usually increases the solubility of solids like sugar. - 10
A warm saturated sugar solution is carefully cooled and still contains more dissolved sugar than it normally could at the cooler temperature. What kind of solution is this?
Supersaturated means more than the usual maximum amount is dissolved.
This is a supersaturated solution because it contains more dissolved solute than a saturated solution normally can at that temperature. - 11
Look at the data: Solution A has 5 grams of salt in 100 milliliters of water. Solution B has 15 grams of salt in 100 milliliters of water. Solution C has 15 grams of salt in 300 milliliters of water. Rank the solutions from most concentrated to least concentrated.
Solution B is most concentrated because it has 15 grams in 100 milliliters. Solutions A and C are tied because A has 5 grams in 100 milliliters and C has 15 grams in 300 milliliters, which both equal 0.05 grams per milliliter. - 12
A diagram shows three beakers. Beaker 1 has clear salt water. Beaker 2 has sand and water with sand settled at the bottom. Beaker 3 has oil floating on water. Which beaker contains a solution, and how can you tell?
A uniform mixture has the same appearance throughout.
Beaker 1 contains a solution because the salt is dissolved evenly in the water and the mixture looks uniform throughout. Beakers 2 and 3 are not solutions because their parts are visible and not evenly mixed.