01: Video Tutorial for Matter and Measurement
- Page ID
- 43955
Take notes while watching the following video tutorials to prepare for the “Matter & Measurement Activity”.
Measurement Part 1:
Significant Figures are used to communicate measurement uncertainty.
Rules for Significant Figures (Sig Figs):
0.0032005700
Round each of the following numbers to the number of sig figs indicated in ( ).
- 6,478 (two)
- 0.000793 (two)
- 456,924 (three)
- 0.05307 (three)
- 4000 (two)
Important Distinction!
Zeros are important place holders to preserve the overall value of the measurement. Sig figs are about the accuracy and precision of the measurement.
Round 689,532 to the indicated number of sig figs:
Four:
Two:
Round 0.0027869 to the indicated number of sig figs:
Four:
Two:
Significant Figures in Calculations:
- For multiplication and division, the result is limited by the term with the smallest number of significant figures:
7.05 ft x 2.6 ft =
5.0 mL x 13.9 g =
mL
- For addition and subtraction, the result is limited by the term with the least precision. Look at what digit place has the uncertainty – the hundreds, tens, ones, tenths, hundredths, . . . ?
7.05 ft
+ 2.6 ft
63,200 g
+ 365 g
Measurement Part 2:
Scientific Notation
Exponents – a very brief review
Exponents > 1
Exponents < 1
Converting from Decimal to Scientific Notation
Learn to use your calculator to toggle back and forth between decimal and scientific notation.
Learn how to enter numbers in scientific notation into your calculator.
Convert the following numbers from decimal to scientific notation or vice versa.
3.500 x 10-3
238,000
2.021 x 105
0.000167
Mathematical Operations with Scientific Notation
Multiplication
Division
Be Aware of the Order of Operations
Practice Problems – solve the following
(2.340 x 10-3) x (2.6 x 106) =
3.506 x 103 =
(5.7 x 107) (2.61 x 10-2)
7.4 x 10-2 =
(3.248 x 106) (6.50 x 10-3)
Measurement Part 3: Converting Between Units
Converting between Metric Units – 2 Approaches
- Unit Conversion Factors
How many mg are in 0.53 g?
- Shifting Decimals by adding/subtracting exponential terms
How many dg are in 3,475,892 mg?
How many mL are in 0.375 kL?
Converting Between Metric and English Units - 3 important bridges
What is the kilogram weight of a 210 lb patient?
A typical member of the species Vibrio cholerae is 8.8 x 10-6m long. How long is this in inches?
Using Multiple Conversion Factors
Horse racing uses the distance of furlongs. If a mile is defined as 8 furlongs, how many kilometers is a 22 furlong race?
There are 42 gallons in one barrel of crude oil. How many mL of crude oil are contained in one barrel?
Measurement Part 4: Dosage Calculations
Dosage Calculations
An antibiotic is prepared in 3.0 mL ampoules that contain 60.0 mg of drug. How many mL of the solution should be administered to a patient prescribed 45 mg per injection?
Ivermectine is used to treat dogs that have intestinal parasites. The effective dosage of this drug is 1.5 mg/kg of body weight. How much invermectine should be given to a 17 lb dog?
The doctor ordered 20. mg/kg of a medication for a patient who weighs 36 lbs. The medication is available as 100. mg/mL. How many mL should be given to the patient?
A young child is being treated for a severe ear infection. The pediatrician prescribes amoxicillin at a daily dose of 40 mg/kg to be given in three injections 8 hours apart. If the amoxicillin is supplied as a solution that contains 125 mg amoxicillin per 5 mL of liquid, then how many mL should the child receive in each injection? The child weighs 7.64 kg.
Dosage of IV Solutions – administering drugs gradually over time to allow for different metabolism rates
Flow rate = dosage per unit time
A medication is given intravenously at the rate of 250 drops per min. The medication’s concentration is 450 ng/mL (450 ng/mcL). What is the weight, in grams, of the medication delivered to the patient in 24 hours? (15 drops = 1.0 mL)
A patient is given intravenous morphine at a rate of 0.35 mg per hour. At this rate, how many minutes will it take to give the patient 1.5 mg of morphine?
Measurement Part 5: Energy & Specific Heat
Energy – the capacity to do work
Heat – a form of energy
Temperature – a measure of the hotness or coldness of an object
Heat vs Temperature
The units for heat:
Specific Heat (SH)
The heat needed to raise 1.00 g of any substance by 1°C.
The units of specific heat:
Specific Heats for Some common Substances
Substance | SH (cal/g·°C) | Substance | SH (cal/g·°C) |
Water | 1.00 | Wood – average | 0.42 |
Ice | 0.48 | Glass – average | 0.22 |
Steam | 0.48 | Rock - average | 0.20 |
Iron | 0.11 | Ethanol | 0.59 |
Aluminum | 0.22 | Methanol | 0.61 |
Copper | 0.092 | Ether | 0.56 |
Specific Heat calculations use the following equation:
Calculate the number of calories of heat energy required to heat 25.0 g of copper from 23.0°C to 34.7 °C.
Calculate the final temperature after 175 cal of heat energy is added to 7.73 g of water at 43.2°C.
What is the mass, in grams, of a piece of aluminum if its temperature changes from 30.0°C to 315 °C when it absorbs 1770 cal?
Measurement Part 6: Specific Gravity
Specific gravity is the density of a substance relative to water ( 1.00 g/mL)
The specific gravity of urine can be used diagnostically. Normal urine has a specific gravity between 1.010 and 1.030.
Figure 1: Hydrometer (left) used to measure specific gravity and typical reading from a modern refractometer (right). In adult humans, normal specific gravity values range from 1.003 to 1.03.
Solids, Liquids, and Gases Part 1: Temperature
Temperature – a measure of the hotness or coldness of an object
When converting between temperature units we must consider
1)
2)
°F = 9/5 (°C) + 32 K = °C + 273.2
The hottest temperate ever recorded in the US was 56.7 °C in Death Valley, California. Convert this temperature into °C and K.