Transcript
Scientific Notation 1,000,000 = 1 million
Scientific Notation 1,ooo,ooo = 1 million = 1 x 106
Move the decimal point to a value between 1 and 10
1 000 000. ------> 1 x 106
Move the
Decimal 6 places to the
left
Scientific Notation
There are 0.0000001 H+ ions in a neutral solution
Scientific Notation
There are 0.0000001 H+ ions in a neutral solution
= 1 x 10-7 H+ ions
Scientific Notation Format:
450,000 = 4.5 x 105
0.000073 = 7.3 x 10-5
Number between 1 and 9.99
Power of Ten10 x 10 x 10 x . . .x
Scientific Notation
NaCl crystal
Distance Na+ .. Cl–
0.000000000278 m
Scientific Notation
NaCl crystal
Distance Na+ .. Cl–
0.000000000278 m
= 2.78 x 10-10 m
Scientific Notation
US National Debt (2016)
$18, 200,000,000,000
Scientific Notation
US National Debt (2016)
$18, 200,000,000,000
= $1.82 x 1013
Scientific Notation
Scientific calculators
8.978+01 = 8.978 x 101
= 89.78
5.0627 E+15= 5.0627 x 1015
= 5,062,700,000,000,000
Significant Figures
How do you know how many decimal places to use?
All of the digits known with certainty plus one estimated digit.
Significant Figures
Rules
Any non-zero digit is Significant
Any zero between non-zero digits is Significant
All zeros to the left of the first non-zero digit are NOT Significant
Zeros after the decimal point are Significant
Zeros that occur without a decimal point are NOT significant
Significant Figures
How many significant figures does each value have?
Value # Significant figures
0.00008 m
36,000 km
22.00 g
5.05 x 10-3 mg
Significant Figures
How many significant figures does each value have?
Value # Significant figures
0.00008 m 1
36,000 km 2
22.00 g 4
5.05 x 10-3 mg 3
Significant Figures
When multiplying or dividing, the result cannot have more sig figs than either of the original values
In addition or subtraction, the answer cannot have digits after the decimal than the original values
Rounding: If the first digit to be dropped is 4 or less, the last digit and any following are dropped. If the last digit is 5 or more, the last digit is kept and increased by 1.
Significant Figures
A 2002 Toyota Camry uses 11.70 gallons of gas to travel 278 miles – what is its mileage?
Significant Figures
A 2002 Toyota Camry uses 11.70 gallons of gas to travel 278 miles – what is its mileage?
3 sig figs
278 miles = 23.8 mi/gal
11.7o gallons 3 sig figs
4 sig figs
Significant Figures
A 2002 Toyota Camry uses 11.70 gallons of gas to travel 278 miles – what is its mileage?
3 sig figs
278 miles = 23.8 mi/gal
11.7o gallons 3 sig figs
4 sig figs
The answer CANNOT have more significant figures than the input value with LESS sig figs.
Significant Figures
Significant Figures
Blood cholesterol level = 185 mg/dL
= ?? g/L
How many g of
cholesterol are in 5 Liters
Of blood?
Significant Figures
Blood cholesterol level = 185 mg/dL x g/1000mg x 10dL/L
= 1.85 g/L
How many g of
cholesterol are in 5L blood?
1.85 g/L x 5 L
= 9.25 g = 9 g
The answer is limited to 1 sig fig
Density Archimedes
confirmed that a crown was
made of gold rather than
gold-covered metal by measuring
its density by water displacement
mass
Density =
volume
Density
A piece of lead measures 0.5 cm x 1.55 cm x 25 cm and has a mass of 220.9 grams – what is its density?
Density A piece of lead measures 0.50 cm x 1.55 cm x 25 cm
and has a mass of 220.9 grams – what is its density?
mass
Density = volume
220.9 g
= 19.38 cm3
= 11.40 g/cm3 = 11 g/cm3 [2 sig figs]
Bone Density
Decreases with age (Osteoporosis)
Normal weakened
mgcm3
Body Mass Index (BMI)
Density & Temperature
Density measurement must include temperature
phase changes
Temperature
Temperature is a measure of the amount of Kinetic Energy in a substance
Kinetic Energy = Energy of motion
http://phet.colorado.edu/en/simulation/states-of-matter
Temperature Scales
°C = (°F – 32) x 0.55
°F = (°C x 1.8) + 32
K = °C +273
Temperature Scales°F °C K
57°F
-75°C
6
106°F
°C = (°F – 32) x 0.55
°F = (°C x 1.8) + 32°
K = °C +273
Temperature Scales°F °C K
57°F 14°C 287 K
-103°F -75°C 198 K
-449°F -267°C 6
106°F 41°C 314 K
°C = (°F – 32°) x 0.55
°F = (°C x 1.8) + 32°
K = °C +273°
States of Matter
melting
Freezing
evaporating
condensing
Phase Changes
Boiling Point
For water Tb = 100°C = 373 K
Freezing Point
For water, Tf = 0°C = 273K
Heating & Cooling Curves
Heat of Fusion
Energy necessary to separate particles
For water: 80 cal/g
Heat of Fusion
Ice cube tray hold 325 g water. If the water is originally at 25°C how many calories must be removed to cool and freeze the water at 0°C?
Heat of Fusion Ice cube tray hold 325 g water. If the water is originally at 25°C
how many calories must be removed to cool and freeze the water at 0°C?
Cooling:
325 g x 1 cal/g°C x 25°C = 8125 cal
• Freezing:
325 g x 80cal/g = 26000 cal
TOTAL: 34125 cal = 34.125 kilocalories
Heat of Vaporization
Energy to vaporize 1 g of liquid to gas
Water: 540 cal/g
Steam vs. Hot Water
Why does steam burn more than hot water at the same temperature? (100°C) body temp = 37°C
Hot water:
25 g x 63°C x 1 cal/g°C = 1575 cal
Steam:
25 g x 540 cal/g = 13500 cal
TOTAL: 15075 cal (10x that of hot water)
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