Math of the lab Data collection & analysis
Measurement= accurate data is used to identify science facts Tool must be precise for data to be accurate enough to be reliable
Katie Ledecky has won gold again in the 800-meter freestyle. Her finishing time: 8:04.79s. She finished 11.38 seconds before the silver medal winner, Jazz Carlin of Britain. What was Jazz Carlin’s time? Jazz beat the 3rd place finisher, Boglárka Kapás of Hungary, by two tenths of a second. What was Boglarka Kapas’ time?
Precise measurement for reliable data results The average length of a blink is 100-400 milliseconds. In less than 10 milliseconds, Gale Devers won the women’s 100m sprint in the 1996 Summer Olympics. In 2008, Michael Phelps beat out Tom Shields by less than .01 seconds for the men’s 100m gold medal. In 2014, Netherland’s Koen Verweij lost the men’s 1500m speed skating gold medal by just 0.003 seconds. That’s less than 1/100 of a heartbeat.
Measurement Tasks in chemistry A. Metric is used in science experiments for both extensive & intensive properties B. Significant figures indicate if measurement is reliable C. Scientific notation prevents errors in writing big & small data D. Temperature scales are converted using an equation E. Percent error indicates reliability of data
I. Metric Based on multiples of 10 A. prefixes modify base unit Base unit
Characteristic of sample (can be varied =extensive properties)
Mass Length volume
B. Prefixes=the multiple of 10 to multiply by – Kilo= 1000 times, kilogram= – Milli=.001 times, milligram=
C. Changing prefixes 1. Start at given prefix 2. Determine if you are going to a greater or smaller value(direction on the stairs) 3. Count the number of steps 4. If the #of steps is >the number you have, add zeros
Circle the larger unit in each pair of units or values. 1. centimeter, millimeter 2. kilogram, gram 3. milligram, gram 4. milliliter, liter 5. .001, .1 6. 1000, 1.0x103
Write the equivalent measurement: 1. 2. 3. 4.
9mg= ____g 4ml= ____L 12mg=___g 8g=____mg
5. 6035mm=___cm 6. 7.02ml=____cm3 given:1000joules= 1kj 7. 2000J=____kJ 8. 20500J=____kJ
1. Dr. Thompson had one cereal bar with a mass of 37g. What is the mass of 6 cereal bars? Is that more than or less than 1 kg? Explain your answer. 2. Dr. Thompson is working in his garden he needs 1 kg of potting soil for his plants. He has 750g. How much more does he need? Explain your answer. 3. Which unit would you use to measure the capacity? Write milliliter or liter. a) A thimble c)A bucket b) A water storage tank d)A carton of juice
II. Significant figures? A. Survival depends on the quality of the data. B. How accurate is the data? 1. Depends upon the precision of the measurement device 2. The talent of the scientist 3. The reporting of the data in significant figures
C. Counting Sig Figs R‐59 1. All digits =Sig fig. 2. Zero in middle of number= sig fig ex: 5007= 4sig fig 3. Zero’s @beginning of number NOT sig fig ex: 0.005 =1 sig fig
4. Zero’s @the end • With a decimal point the end zeros are sig fig Ex 6.00 =3 sig fig Ex. 60.50=4 sig fig Ex. 60.00=
• Without a decimal pt Not sig fig Ex 600= 1 sig fig Ex60,000= 1sig fig
• • • • • •
552 55102 501020 5110020.00 0.00102012 5.0000010
D. Rounding answer in Sig fig • 1. Multiply & divide: Product/answer number limited to lowest amount of SIG FIGs of the measurements (data). Ex: data 12m x 4m= 48m=
Data 102m x 15m=
2. Addition & subtraction • Decimal places • Answer has same number of decimal places as least amount in a measurement (data) ex: 54.5m +3.1m +7.82m =65.12 m=
589.544g – 28.00g = 561.544g=
III. Density p89‐90 • Define: ratio of mass over the volume • Math equation (table ) • Physical property unique to the substance it depends on the composition of the substance • elemental densities on table • Temperature impacts density
Yellow Orange Red blue Purple Green
Density flip page: • cut on dashed line, the solid perpendicular line and the outer rectangle. • Glue into book. • On top flaps of check for understanding determine the correct sample to answer the question • Lift flap write a complete sentence explanation based on “composition of sample” &/or Density ratio.
• Using the chart on p. 90:
Why do helium balloons float? –Explain why the BP explosion in the gulf of Mexico was very difficult to clean up. –How might a scientist use this chart? –
IV. Scientific notation(R56‐‐59) 1. Efficient format of a BIG or small # 2. Notation format has two parts: Coefficient X 10 exponent 3. BIG value: decimal moves left
4. Small values decimal moves right
5. Calculations in sci. not. 1. Multiplication: • Multiply the coefficients ADD the exponents
2. division • Divide coefficients Subtract exponents
3. Addition • Exponent Values in same power of 10 • Add coefficients exponent unchanged
4. Subtraction
V. Temperature 1. average kinetic energy of the particles of the sample. • 0Celsius = 273Kelvins • Differing zero points on scales require a given equation: Table T • One degree Celsius = 1 Kelvin
1. 100C= ________k 2. 200C=________k 3. 0k= _______C (this= absolute zero.)
3. Phase change diagram A. Shows “fixed points” on the thermometer
B. Phase changes
• Melting point/ freezing pt ; boiling pt /condensing pt are intensive properties • Elements table S
• Fusion: phase change between solid &liquid • Vaporization: phase between liquid & gas
IV. The 3 states of matter A. Solids: NaCl (s)
Definite shape & volume Orderly arrangement of atoms tightly packed Strongest intermolecular forces Vibrate in position
B. Liquids:NaCl (l) • Definite volume • No definite shape • Intermolecular forces are not as strong as in solid • Particles are close together, but free to flow past ea. other
C. Gas: NaCl (g) • No intermolecular forces • Move: constant random Straight lines • No fixed volume • No definite shape • Compressible!
What is the error in reading the meniscus in”g”
select the two terms in each group that are related. Explain how the terms are related. 1. Celsius degree, mass, Kelvin _________________
2. balance, second, mass ____________________
3. kilogram, liter, cubic centimeter _____________________
4. decimeter, kilometer, Kelvin ___________________
I. To convert unit: multiply by 1 • The conversion fraction =1 • Ex; 1ft=12in, 60 min=1hr • Ex:How many minutes is 4.5 hours?
• 60 minutes=1 hour • 60 min= 1 1 hr • 4.5 hr x 1 • 4.5 hr x 60 min 1 hr • 4.5 x 60 min 1
4.5= 270?! • Dimensions are numbers with units data 1. Choose a fraction =1 2. Choose a conversion factor using the given units and the desired units (hr & min) 3. Write it as an equation: 1hr= 60min or 1 min=.6hr 1. Convert to fraction= desired unit on top Given units on bottom