chapter 2, section 5 mass and volume. august 30, 2011 hw: none 2.3 quiz honors requirements choose...
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Chapter 2, Section 5
Mass and Volume
August 30, 2011HW: None
• 2.3 Quiz• Honors Requirements• Choose Chapter/Section for presentation– Choose from • Ch. 2.6-2.9, • Ch. 6 (skip 6.5 and 6.8), • Ch. 1
• Find current event
2.3 Quiz
• Differentiate between solutions, suspensions, and colloids
Filter Laser Beam Example
Solution
Suspension
Colloid
2.3 Quiz
• Differentiate between solutions, suspensions, and colloids
Filter Laser Beam Example
Solution Pass through Pass straight through
NaCl in water
Suspension Liquid will pass thru, larger particles caught in filter paper
Stops laser beam Soil in water
Colloid Pass through Scatters/spreads out
Milk
August 30, 2011HW: 2.5 CTG, pg 142, #1-9, 11(Due Friday)
• LO– Determine density of liquids and solids– Correctly use significant figures
• SC– Determine the densities of various
liquid and solid materials– Make measurements in the lab to the
precision of the instruments used– Learn the difference between
accuracy and precision in experimental measurements
– Use density measurements to determine the identity of a material
– Locate sources of the variation in the class’s results
• Do Now– Write LO and SC on new
left side page– WDYS/WDYT-pg 134
• Agenda– Do Now– Investigate – Summary
Investigate Part A-pg 134-136
• Set up notebook for #1-5, OK with teacher• Complete #1-5• Graph data as a class (6a)• Answer questions 6b-f in your notebook using
your graph• Complete #7-9• Show teacher your calculations
Investigate Part B: pg. 136-7
• Set up notebook for #1, 3-6. Ok with teacher• Complete #1, 3-6 using the method shown
below• Calculate Density (#6) using
Density=mass/volume
Summary
• Why do some objects float while other sink?– Be sure to use the terms mass, volume, and
density
September 6, 2011HW: 2.5 CTG, pg 142, #1-9, 11 (Due Wed)
• LO– Determine density of liquids and solids– Correctly use significant figures
• SC– Determine the densities of various
liquid and solid materials– Make measurements in the lab to the
precision of the instruments used– Learn the difference between
accuracy and precision in experimental measurements
– Use density measurements to determine the identity of a material
– Locate sources of the variation in the class’s results
• Do Now– Explain the layers in the
density column.– How is it possible for giant
cruise ships and tankers made of steel to float in the ocean? Explain using density.• I know we already did this, but
I want to see if you understand!
• Agenda– Do Now– Chem Talk– Summary
Part C-Teacher Demo
• http://link.brightcove.com/services/player/bcpid34762914001?bckey=AQ~~,AAAAB_wnNRk~,WN9MweAQd_tBaI99JKgDAcW3bUx7peWv&bctid=84449964001
Chem Talk
• What is density?
• What is the equation for Density?
• A measurement of mass per unit of volume
• Density=mass/volume
D
M
V
D=
Chem Talk• When will objects sink?
• When will objects float?
• When will objects neither sink or float?
• When the object is MORE dense than the liquid, it will sink
• When the object is LESS dense than the liquid, it will float on top
• Objects with the SAME density will suspend in the middle of the liquid.
Chem Talk
• How can you measure the volume of a solid?
• Volume=LxWxH• Volume of an irregular
solid: Use water displacement method
Chem Talk
• Significant Figures: • Measurement should be the same as the smallest division on your measurement instrument.
Chem Talk
• Significant Figures… • Calculations:– Adding or subtracting:
• Arrange the numbers so the decimals line up.
• Complete the addition or subtraction.
• Draw a vertical line to mark the end of your least precise number
• The answer should have the same number of decimal places as the least precise number.
12.76+ 3.875 16.635
Answer=16.64
Chem Talk
• Significant Figures… – Multiplying and Dividing• The result should have NO
MORE Sig Figs than the factor with the LEAST amount of significant figures.
• Counting sig figs– 735=3 sig figs– 2008=4 sig figs (zeros count)– 00.0076=2 sig figs (zeros on
the left don’t count)– 820.00=5 sig figs (zeros on
the right count IF there is a DECIMAL point!)
– 230=2 sig figs (no decimal)
Significant Figure Rules
• There are three rules on determining how many significant figures are in a number:– Non-zero digits are always significant.– Any zeros between two significant digits are
significant.– A final zero or trailing zeros in the decimal
portion ONLY are significant.
Practice
• http://www.chem.sc.edu/faculty/morgan/resources/sigfigs/index.html
• Sig Fig Practice 1• Sig Fig Practice 2• Density Practice
Summary
• LO and SC reflection
Relay!
• Get out HW: packet and 2.5 CTG• Density and Sig Fig Relay• 2.5 Quiz
RELAY
• Get a calculator • There are three rules on determining how many significant figures are in a number:– Non-zero digits are always
significant.– Any zeros between two
significant digits are significant.
– A final zero or trailing zeros in the decimal portion ONLY are significant.
D=
D
M
V
RELAY!
• Get a Calculator and be ready for your density relay!