1. Units and Measurements
Mr. Stripling
Pre-AP Chemistry
Room 402

2. SI – used by all countries
Based on 10
Base unit is the starting point
Length, volume, mass, temperature
Also others such as: area, energy, etc.

4. King Henry Died Unexpectedly Drinking Chocolate Milk

5. Length/ Distance https://www.youtube.com/watch?v=djTNUp4XIRo
Measured in ___________ (base unit)
You are going to be measuring some items around the room.
Make a table to record the measurements
Width of lab table
Outlet
Faucet
Height of table (in class area)
Length of table (in class area)
Make sure to record your measurements in centimeters

7. Length/Distance Person is more commonly measured in ___________
Distance between towns or cities would be in ________________
A sheet of paper would be measured in _________
A grain of rice would be measured in ________

8. Mass Create a table to record your findings
Measured in ____________ (base units)
Tissue Box
Calculator
Safety glasses
You are going to measure the mass of :
Piece of paper
Pen
Notebook
Paperclip
Graduated Cylinder
Penny
Graduated Cylinder with 2mL of water
Create a table to record your findings
Graduated Cylinder with 5mL of water
Graduated Cylinder with 10mL of water

9. Volume Base unit _______________ cm3 (cc) and mL 1 mL = 1 cm3
Calculated with measuring or water displacement
Volume = height x width x length

10. Volume Water displacement
Have to measure before and after, find the difference
Not always convenient to measure this way

11. Volume Calculate the volume of the following: Chemistry book Two boxes
Tissue box
Lab table tops (front of room)
Paper clip
Calculator (or cell phone)
Pencil
Thumb tack
Marble

13. Initial Volume
Ending Volume
Calculated Volume
Paper clip
Thumb tack
Pencil
Record calculations in cm3

14. Volume Liquid medicine is most conveniently measured in __________
Bottled soda or water is measured in __________
Water in a swimming pool would be measured in _____

15. Temperature Base unit – Kelvin (K)
We are used to Fahrenheit or Celsius
We can convert from one to the other:
F to C (oF – 32) x 5/9= oC
C to F (oC x 9/5) + 32 = oF
C to K oC = K
K to C K – 273 = oC

16. Temperature 100 oF = ______ oC 22oC = _____ oF 50 oC = _______ K
325 K = ________ oC
How can you convert from Fahrenheit to Kelvin?

17. Graphs Display data Determines patterns
Circle graphs show parts of a whole
Divided into wedges that look like a pie (pie chart)
Wedges equal 100%

18. Graphs Bar graphs show quantities of categories
Quantity measured on the y-axis
Independent variable on x-axis

19. Graphs Most graphs used in chemistry are line graphs
Points on line graph show intersection of data of two variables
Independent variables are plotted on x-axis
Dependent are on the y-axis
Independent variables are those deliberately changed in an experiment
If line is straight (linear), slope can be calculated
Slope = rise / run = y2-y1 / x2-x1

20. Graphs

21. Graphs

22. Graphs
Take the data that you collected from the mass, length, and volume labs and create graphs that you believe would best display your data.
Create a separate graph for each of the labs.

23. Dimensional Analysis Used to convert from one unit to another.
Shows a relationship
We will set it up as a fraction (bridge)
The top has the unit we want to get in to
The bottom has the unit we want to change out of

24. Review Prefixes Base units
Convenient units are not always the base – examples
Keys to converting – always use the base unit in the conversion
Conversion factor
**Know which unit goes on top and which goes on bottom
The conversion factor shows a relationship between the 2 units used in converting

25. Dimensional Analysis
Converting English to Metric using dimensional analysis
Here are the relationships:
1 inch = 2.5 cm
1 ounce = 28 grams
16 ounces = 1 pound
1 cup = 0.24 liters

26. Scientific Notation
Used to express large and small numbers that would have lots of zeros
X.X x 10x

27. Scientific Notation

28. Scientific Notation

29. Scientific Notation

30. Significant Figures Nonzero numbers are always significant
Ex: 72.3 has three
All final zeros to the right of the decimal are significant
Ex: 6.20 has three
Any zero between significant figures is significant
Ex: 60.5 has three
Placeholder zeros are not significant. Remove placeholder zeros by rewriting the number in significant figures
Ex: and 4320 each have three

31. Density
Density – a physical property of matter and is defined as the amount of mass per unit volume.
Common units of density for solids:
Grams per cubic centimeter (g/cm3)
Common units of density for liquids and gasses:
Grams per milliliter (g/mL)

32. Density Usually cannot be measured directly Density equation:
Density = mass / volume

33. Density Classwork
On page 62 do problems: 65 (list, don’t draw),66, 67, 68
On page 64 do problems: 103 & 105
On page 977 do problems: 1 & 2
Show your work or receive no credit

34. Uncertainty in Data
Accuracy – how close a measured value is to an accepted value
Precision – how close a series of measurements are to one another

35. Error
The difference between an experimental value and an accepted value.
Calculating error:
Error = experimental value – accepted value

36. Error
Percent error expresses error as a percentage of the accepted value.
Percent error = (IerrorI / accepted value) x 100
Important way of showing the precision of our calculations

37. Error Classwork On page 49 do problems: 32, 33, 34
Show your work or receive no credit

38. Classwork
Do page 41 practice problem 11 and 12 (total of 12 problems) – express in scientific notation
Do page 51 practice problems 35 and 36

39. Classwork Do the following problems:- #13 (a-d) on page 42
#99 (a-f) and #100 (a-f) on page 64