Tuesday, September 24, 2013

Unit 2 Chemistry: Day 6 Investigating Density

READ TO FIND OUT the definition of density. Write summaries and then answer the questions on the back.
What is Density?
Regular Soda Vs. Diet Soda 
1     Here's an easy science experiment to do at home. Take a can of regular soda and a can of diet soda and put them into a container of water. Most likely the regular soda will sink, and the diet soda will float. Why? The answer is density.
2     What is density? Density is simply the amount of "stuff" in a given space. Scientists measure density by dividing the mass of something by its volume (d = m/v). The volumes of both cans of soda are the same. To find the mass of the sodas, you would have to use a scale. When you mass each of the cans of soda, you would find that they are different. Even though both cans are exactly the same size and shape and have exactly the same volume of soda (twelve fluid ounces), the masses are different. This is because the can of regular soda has more density due to the sugar dissolved in the soda. It will be heavier than the diet soda, and that is why it will sink.
7-Layer Density Experiment
3     Density is an important physical property of matter that describes how closely the atoms of a substance are packed together. The more closely packed the atoms, the more density the substance has. Since different substances have different densities, scientists can measure the density of a substance to identify the substance. They can also use the measure of density to find out if the substance will sink or float.
4     Density compares an objects’ mass to its volume. Since density compares mass to volume, density is written as grams per milliliters (g/ml).
6     Have you ever noticed what happens to a bottle of oil and vinegar salad dressing after it has been shaken? The shaking causes it to mix, but if it sits for a while, the oil will rise to the top and the vinegar will settle to the bottom of the bottle. This happens because oil is less dense than vinegar.

 7     Density also explains why ice floats. Ice is just frozen water, right? So why does ice float in water? The density of ice is less than the density of water.
Reading Questions

1) Define density: ___________________________________________________________________________________

2) How do scientists measure density? __________________________________________________________________________________

3) Why do you think that diet soda floats, but non-diet soda does not?


4) Which object is more dense: a baseball or a tennis ball?

Explain why: _________________________________________________________________________________

5) Which object is more dense: a pencil or a pen?

Explain why: _________________________________________________________________________________

6) Which object is more dense: an empty bottle or a full bottle? Both bottles are the same volume.

Explain why: ________________________________________________________________________________

 DENSITY Lifework: due Wednesday, September 25, 2013

  1. Define density:  

  1. There are two cubes. One is really dense. One is not dense. Draw the atoms in them to show this!

  1. If we melted the cubes above into liquids, which one would float? How do you know?

  1. If I put these 4 liquids into a graduated cylinder, how will they stack up? Draw it! 

  1.  I have one cube made foam and one cube made of metal.

a.    Do they have the same volume? ____________________
b.    Will they have the same mass? _____________________
c.     Will they have the same density? How do you know?

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