Mass and Volume
A graduated cylinder/syringe can be used to measure _____________. A balance scale can be used to measure ______________.
What is the word to describe a less concentrated solution?
Dilute
What is density?
Density is the amount of mass/matter per unit of volume. In other words, it is how much stuff is in a certain space.
How do you know when a solution is saturated?
A solution is saturated when no more solute is able to dissolve. The solute that cannot dissolve sits at the bottom of the container.
Name the unit we have been using to measure mass. Name the unit we have been using to measure volume.
Grams
Milliliters
You make three different salt solutions. Here is how you mix them:
Solution 1: 5 grams of salt into 50 mL of water
Solution 2: 5 grams of salt into 100 mL of water
Solution 3: 10 grams of salt into 100 mL of water
Which ones have the same concentration?
Solutions 1 and 3
If an object is more dense than a liquid, it will ________. If an object is less dense than a liquid, it will _________.
Sink, float
Citric acid is (more/less) soluble than sodium chloride because...
It is more soluble because more citric acid can dissolve in a given volume of water than sodium chloride in the same volume.
For example, a maximum of 67g of citric acid dissolves in 50 mL of water, while only 17g of sodium chloride dissolves in 50 mL of water.
What are two ways to increase the concentration of a solution?
Increase the mass of solute
Decrease the volume of solvent
What are 3 different ways you can determine whether one solution is more concentrated than another? (Think about different senses we can use to observe.)
Taste: The more concentrated solution will have a stronger taste/flavor.
Sight: The more concentrated solution will have a darker color or be less transparent.
Feel: We can measure the mass of the same volume of each concentration.
Look at the density column picture. Which layer is most dense? Which layer is least dense? How do you know?
Most dense: Honey because it sinks to the bottom layer.
Least dense: Vegetable oil because it floats to the top layer.
Name two ways you can determine the identity of an unknown solute after it has been dissolved in a solvent.
You can measure the mass of solute that dissolved in the solvent to make a saturated solution. You can also evaporate the solvent from the saturated solution, and observe the crystal shape.
What are two ways to make a solution more dilute?
Decrease the mass of solute
Increase the volume of solvent
You are making lemonade to sell at a lemonade stand. You mix 5 spoonfuls of lemonade powder into 250 mL of water, and it makes the perfect batch. You end up selling out of that batch and want to make another bigger batch. How many spoonfuls of powder should you mix into 1,000 mL so that you get the same concentration and flavor as the first batch?
20 spoonfuls
250 mL x 4 = 1,000 mL
5 spoonfuls x 4 = 20 spoonfuls
You measure a volume of 50 mL of water, oil, and honey. Then you compare the masses of these 3 liquids.
Water = 50 g
Oil = 45 g
Honey = 65 g
Based on the mass measurements, put the liquids in order from MOST to LEAST dense.
Most: Honey
More: Water
Least: Oil
Look at the five cups of tea. Each has the same amount of tea, but a different amount of sugar added.
There is no sugar at the bottom of cups A, B, and C, but they taste different. Explain why they look the same but taste different.
All of them look the same because all of the sugar is dissolved, so they are all transparent. They taste different because each one has more sugar in it than the last one, so they get sweeter the more sugar there is.
Before comparing the mass of two solutions, you need to measure equal volumes. Why do you need to have equal volumes if your goal is to figure out which solution is more concentrated?
If you have unequal volumes the one with more volume will have more mass from the liquid. We need to know the difference in the mass of the salt in order to compare concentrations, not the mass of the liquids.
Ms. Schake was mixing some Kool Aid into her water this morning. She put some powder mix in and taste tested it. It tasted way too strong/sweet! How would you suggest she fixes this problem? Draw a model of her Kool Aid solution before and after this adjustment.
You could add more water to dilute the solution. The model should have the same amount of solute particles and show a greater volume/higher level of water.
Look at the picture comparing equal volumes of 2 mystery solutions. Tell me what you know about the mass, concentrations, and densities of these solutions.
Solution 2 has a greater mass than solution 1.
Solution 2 has a greater concentration than solution 1.
Solution 2 has a greater density than solution 1.
Look at the five cups of tea. Each has the same amount of tea, but a different amount of sugar added. There is sugar at the bottom of cups D and E.
1. Explain why there is sugar at the bottom.
2. Explain whether or not the tea in the two cups will taste the same or different.
There is sugar at the bottom of cups D and E because they are saturated solutions, meaning no more than 3 spoons of sugar will dissolve.
They will taste the same because no more sugar was able to dissolve, so they won't get any sweeter.