Percent Error and Density Calculation

Tuesday: percent error, density, quiz

• Don’t forget to park your cell phone!

• Work on your method of study (MOS)

• QUIZ : Dimensional Analysis, Scientific Notation, Sig Figs

• Fri 9/1 pennies lab quiz (open notes)

• Monday 9/4- NO SCHOOL, labor day

• Tuesday 9/5

• Wed 9/6: Unit 1 test

Announcements/Reminders

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Bellwork:

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Agenda

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quiz review on GC

• review: percent error & density

• Quiz 1 (15 minutes)

• percent error & density practice on GC (pg 15-16 in workbook)

• read density of pennies lab intro pg 17 and design a procedure

HW:

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• finish percent error & density practice on GC

Percent Error

○ There are two types of error in measurement:

○ Systematic error → error is in one direction only

○ Ex. Bathroom scale always reads 2 pounds

○ Random error → error that fluctuates in both

directions

○ Ex. Bathroom scale says 2 pounds one time, and 100

pounds the next time

<<time>>

Percent Error

○ The melting point of carbon is 3,550 degrees Celsius. In

lab, a student calculated the melting point as 3,446
degrees Celsius. What is the student’s percent error?

3446 – 3,550
___________ X 100 = 2.93%
3,550

<<time>>

Density-Amount of matter present in a given
volume of substance (how compact is it?

○
○

D = m

v

○ Units are g (for solids) or g (for liquids)

cm3

mL

○ Ex. A block has a volume of 25.3 cm3. Its mass is

21.7 g. What is its density?

3

D = m = 21.7 g = 0.858 g/cm3

v

25.3 cm3

Density

○ Determined by dividing the mass by the

volume.

D- density (g/cm3)

m – mass (g)

V – volume (cm3 or liters)

<<time>>

Multiple Choice

The attendance for the basketball game was estimated to be 15,000 people but 12,500 people attended. What was the percent error?

• 16.67%

• 20%

• 2500%

• 80%

Multiple Choice

Jessie estimates the weight of her cat to be 8 pounds.  The actual weight of the cat was 10 pounds.  Find the percent error.  

• 15%

• 20%

• 25%

• 30%

Unit 1 quiz - 10 multiple choice
on formative (20 minutes)

After Quiz:
percent error & density practice on GC
(pg 15-16 in workbook)

• read density of pennies lab intro pg 17 and design a procedure