Density Fundamentals
What is the formula for density? (think broken heart)
density = mass/volume
If an object has a mass of 100 g and a volume of 10 mL, its density would be: (include the units)
d = m / v
= 100 g / 10 mL = 10 g/mL
T/F
Can a controlled variable be independent?
Can a controlled variable be dependent?
Can a dependent variable be independent?
F
F
F
As mass increases, density will ______.
As mass decreases, density will ______.
increase, decrease
If we have two different objects with the same volume, the object with the smaller mass would have a ____ density. Explain why.
The object would the smaller mass would have a smaller density. Since the volume is held constant, density will decrease as the mass is smaller.
For the following research question:
"How does the amount of sugar added to a cup of coffee impact its temperature?"
What is the independent variable?
The independent variable is the amount of sugar added.
As volume increases, density will ______.
As volume decreases, density will ______.
decrease, increase
You are given distinct two cylinders with the same mass. What could be said of the density for the cylinder with the smaller volume?
For the following research question:
"How does the amount of sugar added to a cup of coffee impact its temperature?"
What is the dependent variable?
The dependent variable is the temperature of coffee after sugar is added
If an object is less dense than a liquid, the object will ___ in the liquid.
If an object is more dense than a liquid, the object will ___ in the liquid.
float, sink
Which state of matter for a given substance has the largest density value and why? Draw a visual to make it clear to your audience.
Solid - it has the most amount of particles pushed into the same volume as compared to liquid and gas since they are rigid and close together. Since the mass of any volume of solid would be greater than that of its liquid/gas, it should have the largest density.
[See visual for how we can picture this idea]
For the following research question:
"How does the amount of sugar added to a cup of coffee impact its temperature?"
What are some possible controlled variables?
Some possible controlled variables could be:
- Volume of coffee
- Brand of coffee brewed
- Brand of sugar used
- Initial temperature of coffee
If you have two samples of the same material, where one sample has more mass and volume. Which of the samples has a greater density?
Since they are made of the same material OR have the same identity, they have the same density.
A carrot floats in salt water but sinks in fresh water. This is because: (explain why the other choices are wrong when you select an option)
(A) - salt water is more dense than fresh water
(B) - fresh water is more dense than salt water
(C) - the carrot is more dense than salt water
(D) - a large piece of carrot has a different density
(A)
In B, if fresh water was more dense than salt water, then the carrot should also sink in salt water but it floats.
In C, if this were true then the carrot should sink in salt water but it floated.
In D, any sample size (no matter the size) will always have the same density because it is made of the same substance OR has the same identity.
Why do we need controlled variables? What purpose do they serve?
Controlled variables are variables that could get in the way of testing out a relationship between only two variables.
Consider the alka-seltzer and vinegar experiment, the number of alka-seltzers placed into a solution was the independent and the final temperature after it mixed was the dependent variable. If I did not control the volume of vinegar, it could be concluded that the volume of vinegar may have had an impact on whether final temperature has changed -- which defeats the purpose of the experiment. It ensures that this test is ONLY between these two variables and ensures validity (or fairness of the experiment).