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.
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
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.
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
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.