env bio lab midterm study guide

ENV BIO LAB MIDTERM STUDY GUIDE

I. The Metric System

What is the Metric System?

The metric system is a decimal system of measurement that allows for easier conversion between different metric units of measurement. The metric system has inherent convenience it the way that it is set up. All of the prefixes are in powers of 10, which makes conversions much easier that conversions between English system measurements. The metric system was invented by the First French Republic back in 1799. It was based on the meter, and over the years has been expanded into larger measurements and subdivisions. The metric system is also known as the International System of Units. Interestingly, the United States remains as the only industrialized country that has not accepted the metric system as its official system of measurement.

WHY IS THE ENGLISH SYSTEM SO ODD?

The English System of Measurement is not nearly so easy to work with. The idea of the foot as a unit of measurement actually came from a a man's foot, literally. The foot (the North German foot) measured 13.2 inches. The foot was used as the basis for the measurement of length. The foot then divided into 4 palms. 1 palm was equal 4 thumbs. long, so palms became another unit of measurement. A cubit was made to be 2 feet long and an elne was 4 feet long. A rod was 15 feet, a furlong was 10 rods.... YIKES

The foot was used as the basis for the measurement of length. The foot then divided into 4 palms. 1 palm was equal 4 thumbs.

To make matter worse, the "foot" in one region was not equal in length to the "foot" of another region. This held true for all measurements. The lack of standardization made for a convoluted mess of oddly defines measurements that had no basis in any real science. For example, the yard, foot, inch, etc. were changed to 10⁄11 of their previous value. The rod went from 5 old yards to 5 1⁄2 new yards. 15 old feet were now to 16 1⁄2 new feet. The furlong went from 600 old feet (200 old yards) to 660 new feet (220 new yards). The acre went from 36,000 old square feet to 43,560 new square feet.

Converting Between English and Metric Units of Measurement

English System	Metric System
2.54 inches (in.)	1 centimeter (cm)
0.305 feet (ft)	1 meter (m)
0.614 yards (yd)	1 meter (m)
1.609 miles (mi.)	1 kilometer (km)
0.964 quarts (qt)	1 liter (L)
3.785 gallons (gal)	1 liter (L)
28.349 ounces (oz)	1 gram (g)
0.484 pounds (lb)	1 kilogram (kg)

MASS vs WEIGHTClick on the Image to go to the EXPLORATORIUM WEB PAGE and see what you would weigh on other worlds! www.exploratorium.edu/ronh/weight/

When we measure MASS, we are only considering the amount of matter the object/entity is made up of. In contrast, WEIGHT takes into consideration the force of gravity exerted on the object.

In the metric system, weight is measured as Newtons. Newtons is a measure of FORCE. It refers to the force exerted on an object with mass by the gravitational pull it is exposed to.

Mass is constant and does not change with respect to the gravitational pull that acts on the object. It is the scientific measure of the amount of matter an object is made up of. No matter where you are at given moment in time, mass is constant. Did you know you weigh more at sea level than you would on a mountain top? Gravity exerts more force on you as you get closer to the Earth's core. So if you want to lose weight, move to the mountain top! Unfortunately, you mass would not change when you make this move.

Formula: W = MG

Where: (W) = Weight
      (M) = Mass
   (g) = Gravitational Acceleration

The value of (g) on Earth is = 9.8 m/s/s . The value of g changes when the acceleration due to gravitation changes.

How to convert Grams to Pounds1 gram (g) is equal to 0.00220462262185 pounds (lbs).
1 g = 0.00220462262185 lb
The mass m in pounds (lb) is equal to the mass m in grams (g) divided by 453.59237:
m(lb) = m(g) / 453.59237
TEMPERATURESThe United States is one of the very few countries that uses degrees Fahrenheit as the measurement for temperature. The unit, degrees Fahrenheit was developed in the 1700's by G. Daniel Fahrenheit).

   The unit of measurement for temperature used by pretty much the rest of the world, is degrees Celsius which was developed in the 18th Century. Sometimes for scientific temperature measurements, especially relating to chemistry and physics, is Kelvin. The Kelvin system has no negative numbers and goes as low as the theoretical "absolute zero." As energy is taken away from an atom or molecule, the temperature is asymptotically decreased approaching, but never reaching, "absolute zero." The chemical properties of matter at its most fundamental level changes as we approach absolute zero. Liquid helium has been shown to go through glass and defy gravity at these extremely cold temperatures of only a few thousandths.

Fahrenheit is a temperature scale created by Daniel Gabriel Farenheit that bases the boiling point of water at 212 and the freezing point at 32.
The three different temperature scales have been placed side-by-side in the chart here (created by Scientist Cindy of www.scientistcindy.com) for comparison.
CONVERTING BETWEEN F and C
They both measure the same thing (temperature!), but use different numbers:

Boiling water measures 100° in Celsius, but 212° in Fahrenheit
And as water freezes it measures 0° in Celsius, but 32° in Fahrenheit
The scales start at a different number (0 vs 32), so we will need to add or subtract 32
The scales rise at a different rate (100 vs 180), so we will also need to multiply or divide
And so, to convert:
from Celsius to Fahrenheit: first multiply by 180/100, then add 32
from Fahrenheit to Celsius: first subtract 32, then multiply by 100/180

But 180/100 can be simplified to 9/5,
and 100/180 can be simplified to 5/9, so this is the easiest way:
°C to °F Multiply by 9, then divide by 5, then add 32
°F to °C Deduct 32, then multiply by 5, then divide by 9We can write each as a formula like this:

Celsius to Fahrenheit: (°C × 9/5) + 32 = °F

Fahrenheit to Celsius: (°F − 32) x 5/9 = °C
Measuring in Multiple DimensionsLength
1 DIMENSION = A meter is a 1-dimensional measurement of a thing. For example, we can say that a desk is 1.5 meters long. 
Area
2 DIMENSIONS = When we measure 2 dimensions, we get the AREA of an object. We can make 2 1-dimension measurements (length and width) and multiply them together to get the AREA with the units SQUARED. For example, to measure the AREA of your desk top you measure the length (say it's 1.5 meters long) and then measure the width (say it's 0.5 meters long). Area is calculated by multiplying the length and width which gives us 0.75 meters squared (or to the 2nd power).
Volume3-Dimensions - Sometimes we need to know how much total space a 3-dimensional object take up. This measurement is called VOLUME. For example, in order to measure the volume of an object like a cube, we must measure 3 dimensions; the length, the width and the height.
For other regularly shaped objects, the field of geometry has given us several formulas for finding volume. For example, the formula for calculating the volume of a cone, a prism and a sphere are shown below.

Volume of a LiquidOK great.... but what about measuring liquids? Liquids do not have a defined shape. However, we could fill up a container that has a defined shape, and then apply the volume formula to the container, assuming the container is really thin. This would work. Luckily for us, special measuring tools for measure liquid have done this work for us!

    In the metric system, the unit for volume of a liquid is mL. The mL was derived from the cubic centimeter, or CC. Hospitals and laboratories often use CC as the unit of measurement for drug injections.

    Graduated Cylinders are calibrated and are very accurate when used and read correctly. In order to read a graduated cylinder correctly, you must take the value of the measurement that is at the BOTTOM of the MENISCUS.
The meniscus is the concave formation that the surface of a liquid forms in a cylinder. This happens because water has a natural cohesive property that tends to cling to the slide of the container it is in. The smaller the surface area of the exposed surface of the liquid is, the more predominant the meniscus will be.

   The measurement should be taken from the bottom of the meniscus. For example, the correct measurement of the liquid in the graduated cylinder shown here, is 20 mL.
Image Courtesy of By PRHaney - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=9472731

Graduated CylinderVOLUME to Mass ConversionsConveniently, 1 mL of water = g of water. You may also want to note that a cubic centimeter (cc) is also equal to 1mL and equal to 1 gram (g).

For example, 10 mL of water = 10 g
40 mL of water = 40 g
A more challenging example...
1 mL of water = g of water