Transcript 20.0 g | 1 mL - WaylandHighSchoolChemistry

(74.0/23.60) + 15.000
• Do stepwise: 74.0/23.60 = 3.14 (rounded to 3SF)
• 3.14 + 15.000 = 18.14 (rounded to 2 decimal places)
• Rules: * or / round to least SF
• + or – round to least decimals
20.0 g and 19.3 g/mL
• Always start with single unit
• 20.0 g | 1 mL = 1.04 mL
| 19.3 g
Same measurement repeatedly…
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Quantitative
Qualitative
Accuracy
Precision
Property
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Measurement with numbers
Description without numbers
Getting the right answer
Getting the same answer repeatedly
A trait
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• Always start with single unit!
• 6.60 lb | 1 kg
| 80.0mg | 1 mL
| 2.2 lb
| 1 kg
| 0.48 mg
= 500. mL or 5.00*102 mL
3 SF because starting # had 3 SF
properties
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color
Boiling point
State of matter
Reacts with oxygen
malleable
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Physical
Physical
Physical
CHEMICAL
physical
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Ag + O2 g Ag2O •
NaCl(s) g NaCl(aq) •
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I2(s) g I2(g)
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Mg(s) g Mg(l)
H2O(g) g H2O(l) •
Elements to compound
Dissolving
Subliming
Melting
Condensing
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chemical
physical
physical
physical
physical
0.00000640301
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Leading zeros never count
Middle zeros always count
Digits 1-9 always count
Therefore 6 SF
• 453 mm | 1 m
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| 103 mm
0.453 m or 4.53*10-1m
Get NaCl out of aqueous solution
• Aqueous solution means the salt is dissolved
in the water, so to get the salt back (like we
did in both labs) evaporate the water!
• Tires wearing down is physical b/c its still a
tire, the composition didn’t change
• The iron poker getting hot is only a physical
change because it can cool down
• Amino acids creating a protein is chemical
because the composition is changed.
• Deposits forming on faucet is physical because
the water is simply evaporating leaving the
dissolved minerals behind
• Kelvin is the absolute temperature scale
because it contains absolute zero! It can
never be negative.
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Bunsen burner
Ring
Test tube brush
Wire gauze
Evaporating dish
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Beaker
Test tube
Funnel
Crucible tongs