Mixtures
What is a mixture?
A combination of two or more things mixed together.
How is a solution different from a mixture?
Answers will vary
Solutions have to have a liquid and a solid part, but mixtures do not.
One material has to dissolve in a solution, but not in a mixture.
Solutions are almost always transparent, but mixtures do not have to be.
True or False: All crystal forms look the same.
False
What are the three phases of matter?
Solid, liquid, gas
What tool would you use to separate sand from shells? Why?
A screen because the sand's particle size is small enough to pass through the holes in the screen, but the shells are too big.
We know that solutions have to have 2 parts: a solute and a solvent. Which one is which?
Solute = solid part
Solvent = liquid part
What does it mean to evaporate?
To evaporate is to change from a liquid to a gas.
True or False: Phase changes require the amount of energy one material has to change.
True
What tool would you use to separate a mixture of toothpicks and coins? Why?
Water because the toothpicks are less dense and would float to the top, while the coins are more dense and sink to the bottom.
True or False: A saltwater solution would taste LESS salty after you poured it through a filter paper. Explain why.
False because all of the salt particles are small enough to pass through the filter. It will taste the same as before.
Why did the salt we mixed look different before and after the water evaporated from the solution?
The salt dissolves, or breaks into tiny pieces, at first. As the water evaporates, the tiny pieces joined back together in their natural crystal form.
True or False: The mass of a material changes as it goes through a phase change.
False
What is an example of a mixture of a solid, liquid, and gas?
Answers will vary
Draw a picture of a material before and after it has dissolved into a solution. (Hint: You may have to make a zoomed in model.)
Before: You should be able to see a liquid part and particles of a solid in the liquid.
After: You should be able to see the liquid part, and the particles of the solid should be drawn much smaller but still present.
You fill up your water bottle with ice and water at the start of the day and find the mass to be 540 g. You accidentally forget it at home on the kitchen counter. When you get home all the ice has melted, so you decide to measure the mass again. What will the mass be and how do you know?
The mass will still be 540 g. Mass is conserved, so even though the ice melted into liquid, the amount of matter in the bottle did not change.
Explain why melting is a phase change, but dissolving is not.
Melting involves the amount of energy the particles have to increase, causing the material to change from a solid to a liquid. Dissolving does not involve a change in energy of the particles, but rather the solid particles just break down into smaller solid particles within the liquid solvent.
You mix a red powder into a clear liquid. After mixing, how will you know that you have made a mixture (not a solution)?
The water may have turned a reddish color and you'll still be able to see powder. OR The water turned a reddish color, and it is no longer clear.
You mix a red powder solute into a clear liquid solvent. After mixing, how will you know that you have made a solution?
The liquid will be a clear red color, and you will no longer be able to see any of the powder.
How will a solid, liquid, and gas act differently when you move it from a sealed container to your hand?
The solid will keep its same shape and size. The liquid will form to the size and shape of your hand. The gas will not maintain any shape or size and will blend in with the air around it.
Here is a list of phase changes: melting, freezing, evaporation, condensation, sublimation, deposition. Which phase changes are the result of particles gaining energy? Which phase changes are the result of particles losing energy?
Gaining: melting, evaporation, sublimation
Losing: freezing, condensation, deposition