Unit 1: density Flashcards
What is mass?
A measurement of how much “stuff” is in an object
What are the units of mass?
metric: grams, kilograms
nonmetric: tons, pounds, ounces
How do you measure mass?
by measuring the weight on an electronic balance
What is volume?
how much space something takes up
What tool should be used to measure the volume of a liquid?
A graduated cylinder
What is density?
A measurement of how tightly packed the particles are in a substance
How do you figure out something’s density?
measure the mass and the volume.
Divide mass by volume to find density.
How could you find the volume of a key?
Use water displacement
Drop the key in a graduated cylinder of water and see how much the water level rises.
How can you find the mass of a teaspoon of powder?
Use a weighboat and an electronic balance.
Make sure you press “tare” so that you only get the mass of the powder, not the powder plus the weighboat.
What is the relationship between boyancy and density?
Less dense substances will float (be boyant) on more dense substances.
More dense substances will sink through less dense substances.
Explain why it is poor word choice to say “heavy things sink and light things float.”
“Heavy” and “light” refer to the weight and mass.
Whether something floats or not has to do with density.
A pebble will sink, but a boat will float. A boat is heavy, while a pebble is light.
The idea that as a substance is heated it tends to get bigger
thermal expansion
What is the relationship between temperature and density?
As substaces are heated, they tend to expand, lowering the density.
As substances cool, they tend to contract, becoming more dense.
Explain how a thermometer works
As the thermometer is heated, the liquid inside expands (same mass, greater volume, lower density).
As the thermometer cools, the liquid inside contracts (same mass, lower volume, higher density).
Explain why 5 grams of steam rises
but 5 grams of rain falls.
They’re both water, right?
Yes, both are water, but in different phases.
The gas phase is less dense than the liquid phase.
Gaseous water (steam) is less dense than air, so it floats up.
Liquid water (rain) is more dense than air, so it sinks (falls).
What is the name of the curve that the water makes?
the meniscus
What is the correct measurement?
5.9 mL
+/- 0.2 mL
What is the correct measurement?
6.62 mL
+/- 0.02 mL
What is the correct measurement?
21.5 mL
+/- 0.2 mL
What is the correct measurement?
44.5 mL
+/- 0.2 mL
What is the correct measurement?
52.8 mL
+/- 0.2 mL
How should you position yourself to read a graduated cylinder?
Read it on the table, at eye level.
You may have to lower yourself to get at the right level. Picking up the graduated cylinder and raising it to eye level is not as good because you might tip it.
What is the correct measurement of the volume of the dinosaur?
0.8 mL
+/- 0.1 mL
Why is the pencil pushing the star down, completely under water?
Floating objects will be only partially submerged.
You have to completely submerge them to get an accurate volume.
