Percent Error and Density
What does Percent Error Sound
Like?
Measuring and calculating
Percent Error tells us how well something was
done. (ie how well you did your experiment….)
Measured Value - Accepted Value
Accepted value
X 100 = percent Error
Lets Try This Together!
Measured=40.35 g
Calculated= 39.25g
40.35g -39.25g
39.25g
= 0.02802 x 100 = 2.8%
Try on your own
Measured: 25.55 g
Calculated: 26.33g
What do you do when it’s Negative!
Measured Value - Accepted Value
Accepted value
X 100 = Present Error
25.55g- 26.33g x100 = -2.962%
26.33
Take absolute Value of the answer = 2.962%
Ratio
What are some examples of ratio’s?
Density
• Mass: Volume
D= M
V
Mass
Volume
M
D
V
Unit
Density = g/ml
Mass = g
Volume = ml or cm3
Lets try this
Mass: 22.6g
Volume: 25 ml
What is the density?
Mass: 22.6g
Volume: 25 ml
22.6g
25 ml
Don’t Forget! 2 Sig Fig
= 0.90 g/ml
On your own
Density: 62 g/cm3
Mass: 12.33 g
12.33g
62 g/cm3
0.19887 ~ 0.20 cm3
Division it gets
flipped
Unit Math:
g
1
cm3
g
=
cm3
1
• Density = 1.869g/cm3
• Volume = 23.6cm3
(1.869g/cm3)(23.6cm3) = 44.1084 ~ 44.1 g