Density

1. Density

2. Density The density is the ratio of mass (stuff that makes up an object) and its volume (the amount of space that stuff takes up). The more mass an object has in a give amount of space, the more dense it is. To say it another way, the more con”densed” the matter is, the more dense it is!

3. Which is more dense? A B m2 m2

4. M D V Density can be calculated using the following formula: Whereas,D = M = V = density M V D = mass volume

5. Mass = M D V D x V Density = Volume = M V M D

6. Example: A wooden block with a mass of 80.0 g is 8 cm long, 3 cm wide, and 4 cm high. Calculate the wooden block’s density. 8.0 cm 3.0 cm 4.0 cm Length = Width = Height = 8.0 cm Volume = L x W x H Volume = 8.0 cm x 3.0 cm x 4.0 cm = 3.0 cm 96.0 cm3 4.0 cm

7. 10th space Mass = Volume = 80.0 g 96.0 cm3 80.0 g Density = 0.833 g/cm3 0.8 g/cm3 96.0 cm3

8. Determining the volume of an irregular object Step 1 Place the object in the overflow can. Step 2 Wait for all of the water to flow out of the overflow can into the beaker positioned below the spout. Step 4 Read the volume of the water in the graduated cylinder. This should equal the volume of the mineral originally placed in the overflow can. Step 3 Take the water in the beaker and pour it into the graduated cylinder. Be sure not to spill any! Overflow Can

9. Density = 2 s per Density = 16 s per 8 s Does changing the size of a pure substance change its density?

10. Density = 2 s per Density = 8 s per 4 s Does changing the size of a pure substance change its density?

11. Density = 2 s per Density = 4 s per 2 s Does changing the size of a pure substance change its density?

12. What happens to the density of a material when you break it into pieces? D = m/v M = 2,000 g V = 1,000 mL D = ? g/mL

13. D = m/v M = 2,000 g V = 1,000 mL D = ? g/mL

15. M = 24 g V = 12 mL D = ___ g/mL M = 10 g V = 5 mL D = ___ g/mL M = 14 g V = 7 mL D = ___ g/mL Answer: The density does not change !!!

16. What happens to the density, volume and mass of most materials when you heat them? D = m/v M = 10 g V = 1 mL D = ____ g/mL D = m/v M = 10 g V = 1 mL D = ____ g/mL

17. D = m/v M = 10 g V = 1 mL D = ____ g/mL D = m/v M = 10 g V = 2 mL D = ____ g/mL

18. D = m/v M = 10 g V = 3 mL D = ____ g/mL D = m/v M = 10 g V = 1 mL D = ____ g/mL

19. D = m/v M = 10 g V = 1 mL D = ____ g/mL D = m/v M = 10 g V = 5 mL D = ____ g/mL → No change → Increases →Decreases

20. Sink or Float? An object will sink in a fluid with a lower density and float in a fluid with a greater density.

21. 0.8 g/mL 1.0 g/mL 1.5 g/mL 2.0 g/mL D= 1.8 g/mL D= 2.5 g/mL D = 1.0 g/mL D= 0.75 g/mL

22. The closer the object's density is to the fluid's density, the more under the surface it will be. Why do somethings float at different levels than others? D = 0.2 g/mL D = 0.9 g/mL D = 1.0 g/mL

23. Finding the Percentage BELOW the Surface Step 1 Divide the density of the object by the density of the fluid it is floating in. Ex. Ice = 0.92 g/mL Water = 1.0 g/ml Step 2 Multiply your answer from Step 1 by 100. This equals the percent found BELOW the surface. Ex. 0.92 x 100 = 92% This means 92 percent of an ice cube is found below the surface of water.

24. 8.0 % Above If the density of ice is 92% of the density of water, than 92% is found BELOW the surface. How much is found above? Ice 92.0 % Below Water

25. Try this example! An object with a density of 1.3 g/mL is placed in a cup of pure water (density of water is 1.0 g/mL). What percentage of the object is found below the surface?