1. Ms. Samayoa Chemistry A Birmingham Community Charter High School
Measurement
Ms. Samayoa
Chemistry A
Birmingham Community Charter High School

2. Warm-Up
On your handout, there is an article from the Los Angeles Times. Actively read it for five to ten minutes and then we will discuss the article with the class later on.

3. Learning Targets
Students will be able to identify and differentiate between imperial and metric units
Students will be able to identify unit prefixes
Students will be able to convert units (dimensional analysis)

4. Measurement Every measurement always has a unit
INCORRECT: Distance = 5
CORRECT: Distance = 5 meters
Meter will be knows as a unit

5. Imperial Units In science, wedoNOTuse“old”unitsAKAimperialunits
The following are known as imperial units
Miles
Yards
Inches
Feet
Pounds
Ounces
Gallons, etc

6. Metric Units Instead in science, wealwaysusemetricunits
The following are known as metric units:
Meters
Grams
Liters

8. Prefixes

9. Every time you see a POSITIVE exponent, that is how many times you move the decimal to the right
Every time you see a NEGATIVE exponent, that is how many times you move the decimal to the left

10. SI Base Units

11. First Example
For example, if I ask you to write “2 megameters” in numerical form...
First step: Take a look at the main number.
In this case the main number is 2
Second step: Take a look at the prefix.
In this case, the prefix is mega
According to the prefix table, mega means 106
Since the exponent is positive 6, move the decimal 6 times to the right
2,000,000
Third Step: Take a look at the SI base units
The SI base unit is meters
So 2 megameters means 2,000,000 meters

12. First Example 2 megameters 2,000,000 meters 2 x 106 meters
That is a lot of zeroes to write
So what scientists do is simply write 2 x 106 meters
That is just another way to write 2,000,000 meters without having to write all the zeroes
This is known as SCIENTIFIC NOTATION
2 megameters
2,000,000 meters
2 x 106 meters

13. Second Example
For example, if I ask you to write 3 nanometers in numerical form…
First step: Take a look at the main number.
In this case the main number is 3
Second step: Take a look at the prefix.
In this case, the prefix is nano
According to the prefix table, nano means 10-9
Since the exponent is negative nine, move the decimal to the LEFT 9 times
Third Step: Take a look at the SI base units
The SI base unit is meters
So 3 nanometers means meters

14. Second Example 3 nanometers .000000003 meters 3 x 10-9 meters
Again, meters has a lot of zeroes
Can also be a pain to count the zeroes
Hence, what scientists do is write 3 x 10-9 meters
Remember that this is known as SCIENTIFIC NOTATION
3 nanometers
meters
3 x 10-9 meters

15. Learning Check Let’s say you want to buy an iPhone
At the store, you see one iPhone that has 20GB of memory and another iPhone that has 80000MB of memory for the same price.
Which iPhone would you buy and why?

16. Additional Problems on the Board

17. Converting Units
In order to convert units, you need to understand ratios
When converting units, a conversion table already includes ratios
For example, 1 cm = 10 mm, is a ratio

18. Learning Check
Let’s say we want to convert 3 kilometers into meters

19. Learning Check
Try to convert 3 miles into kilometers

20. We can also take it further (Honors)
Try to convert 5 miles to centimeters

21. Converting Units Activity (Honors)
Try to convert your partner’s height to inches
Then try to convert the height to centimeters
Then try to convert the height to decimeters
With your partner, find something that you want to measure in the classroom
It can be books, the board, something that gets you out of your seat
Try to measure it in centimeters
Now try to convert it into meters

22. Ms. Samayoa Chemistry A Birmingham Community Charter High School
Density
Ms. Samayoa
Chemistry A
Birmingham Community Charter High School

23. Warm-Up
Using algebra, rearrange the equation 𝑎= 𝑏 𝑐 to isolate the following variables…
b = ?
c = ?

24. Volume (Derived Units)
Volume is the amountofspaceanobjecttakesup
Volume can be measured with a graduated cylinder
Have to read the graduated cylinder at the MENISCUS
Graduated cylinders measure in mL
DONOTMEASUREVOLUMEWITHABEAKER
Units: Liters (L), milliliters (mL)

25. At every station there is a graduated cylinder
Take turns on going to every station and determine the volume measurement of water

26. Density: Mass vs Weight
Matter is anything that takes up space
Mass is the measureoftheamountofmatterinthebody
Weight is the measure of the amount of force acting on a mass due to gravity

27. Comparison of Mass vs Weight
property of matter
Mass of an object is the same everywhere
Mass can never be zero
Mass is usually measured in grams and kilograms
Weight
Weight varies depending on gravity
Weight can be zero if no gravity acts upon it
Measured in Newtons

28. 𝐷= 𝑚𝑎𝑠𝑠 (𝑖𝑛 𝑔𝑟𝑎𝑚𝑠) 𝑣𝑜𝑙𝑢𝑚𝑒 (𝑖𝑛 𝑚𝐿 𝑜𝑟 𝑐𝑚 3 )
Finally…Density
Density of a substance is the relationship between the mass of the substance and how much space it takes up (volume)
𝐷= 𝑚𝑎𝑠𝑠 (𝑖𝑛 𝑔𝑟𝑎𝑚𝑠) 𝑣𝑜𝑙𝑢𝑚𝑒 (𝑖𝑛 𝑚𝐿 𝑜𝑟 𝑐𝑚 3 )
Units for density is
𝑔 𝑚𝐿 or 𝑔 𝑐𝑚 3

29. Find the mass of the object Find the volume of the object
To find the density
Find the mass of the object
Find the volume of the object
Divide : Density = 𝑚𝑎𝑠𝑠 𝑜𝑓 𝑡ℎ𝑒 𝑜𝑏𝑗𝑒𝑐𝑡 (𝑖𝑛 𝑔𝑟𝑎𝑚𝑠) 𝑣𝑜𝑙𝑢𝑚𝑒 𝑜𝑓 𝑡ℎ𝑒 𝑜𝑏𝑗𝑒𝑐𝑡 (𝑖𝑛 𝑚𝐿 𝑜𝑟 𝑐𝑚 3 )

30. Learning Check
1 Frank has a paper clip. It has a mass of 9g and a volume of 3cm3. What is its density?
2. Frank also has an eraser. It has a mass of 3g, and a volume of 1cm3. What is its density?
3. Jack has a rock. The rock has a mass of 6g and a volume of 3cm3. What is the density of the rock?

31. Ways to Affect Density (Honors)
Change Mass AND Keep Volume Same
Increase the mass  increase density
Decrease the mass  decrease in density
Which container has more density?
A B

32. Which container has more density?
Ways to Affect Density
Change Volume AND Keep Mass Same
Increase the volume  decrease density
Decrease the volume  increase density
Which container has more density?
A B

33. What 2 ways will INCREASE density?
Keep the same mass AND decrease the volume
Keep the same volume AND increase the mass

34. Density and Buoyancy Density of water = 1 𝑔 1 𝑚𝐿
If the density of an object is > 1 𝑔 1 𝑚𝐿 , it (floats/sinks) in water
Example: Lead density = 𝑔 𝑚𝐿

35. Density and Buoyancy Density of water = 1 𝑔 1 𝑚𝐿
If the density of an object is < 1 𝑔 1 𝑚𝐿 , it (floats/sinks) in water
Example: wood = 0.6 𝑔 𝑚𝐿

36. Learning Check
Calculate the volume of a piece of metal if its mass is 222 g and its density is 5.34 g/mL
Answer 41.6

37. Water Displacement
Record the initial volume of water by reading the BOTTOM of the meniscus
Add the object in the graduated cylinder
Record the final volume of water
𝐹𝑖𝑛𝑎𝑙 𝑣𝑜𝑙𝑢𝑚𝑒 −𝑖𝑛𝑖𝑡𝑖𝑎𝑙 𝑣𝑜𝑙𝑢𝑚𝑒=𝑣𝑜𝑙𝑢𝑚𝑒 𝑜𝑓 𝑜𝑏𝑗𝑒𝑐𝑡

38. LEARNING CHECK Find the volume of the hammer.
The initial volume is 65 mL
Once the hammer is put inside, the meniscus rises to 69 mL
69 mL is the final volume
So according to the equation: 𝐹𝑖𝑛𝑎𝑙 𝑣𝑜𝑙𝑢𝑚𝑒 −𝑖𝑛𝑖𝑡𝑖𝑎𝑙 𝑣𝑜𝑙𝑢𝑚𝑒=𝑣𝑜𝑙𝑢𝑚𝑒 𝑜𝑓 𝑜𝑏𝑗𝑒𝑐𝑡 69 𝑚𝐿 −65 𝑚𝐿=4 𝑚𝐿
4 mL will be the volume of the hammer

39. LEARNING CHECK (HONORS)
Calculate the volume of water, in milliliters, that would be displaced by 1.82 grams of cobalt, when cobalt's density is g / mL