CHAPTER 1

            CHEMISTRY IS EASY! Do you agree? Everything around you is chemistry - the desk you are sitting at, the air you breathe, the food you eat. If you breathe and eat you have been doing chemistry.

            The two major classifications of everything we know is MATTER AND ENERGY.

            Matter is anything that occupies space and has mass (weight). Energy is the ability to change matter, either physically or chemically. Einstein gave an equation which showed a relationship between matter and energy : E = mc² E stands for energy, m stands for mass and c stands for the speed of light.

            If we keep breaking down matter to its simplest stuff, we will finally get to atoms. How many kinds of atoms are there? The periodic chart lists them: approximately 90 naturally occurring atoms and the rest are man made radioactive atoms.

ORGANIZATION OF MATTER

ELEMENTS - Think of them as letters of the alphabet. The letter "a" can also be a word. Most of the time we put letters together and made words. The chemical symbols for the elements are given in the periodic chart.

COMPOUNDS - Think of these as words. H₂O is the formula for water. It has 2 hydrogen atoms and one oxygen atom. Every water molecule will have the same formula. There may be impurities in the water, but all water is H₂O. Compounds are PURE SUBSTANCES, meaning that it has a fixed and definite composition.

MIXTURES - Mixtures have several substances present and can vary from one sample to another. Salt dissolved in water can be a mixture. Two salt solutions can vary by the amount of salt dissolved in the water.

ENERGY

Another definition of energy is the ability to do work. Energy can be divided ino potential and kinetic energy. Potential energy is the energy by location or position. Kinetic energy is the stuff we see and feel that does the work.

Some to the major kinds of energy are heat, electrical, light, radiant, mechanical, and chemical.

Energy can affect matter. Too much heat energy can turn a steak into a clump of charcoal. Depending upon the substance heat is working on, the change can be either PHYSICAL or CHEMICAL CHANGES

A physical change occurs without a change in composition. A chemical change changes the chemical composition.

ICE, WATER, and STEAM are all made up of water H₂O. The have the same formula but have different physical forms. This is the the stages of matter: solid, liquid, and gas.

Ice is solid H₂O. Water is liquid H₂O. Steam is gas H₂O.

Solid Liquid Gas

A solid has the atoms packed closely together. It has the least movement of the atoms. The liquid has more movement in its atoms and the gas has a great deal of movement. As you add heat to atoms, the atoms increase their movement. The more you heat them, the more they move. The gas has the greatest movement and the greatest volume.

In this instance heat made a physical change on the substance. If you heated sugar enough to char it, you would get a chemical change. The product cannot be changed back to the original form. A physical change the substance has the same formula for the beginning and final product. With a chemical change the formula of the final product is different from the original product.

MEASUREMENTS AND THE METRIC SYSTEM

A. Math Review

100 = 10² = 10 x 10
1000 = 10³ = 10 x 10 x 10
10 = 10¹
1 = 10⁰
0.1 = 10^-1 = 1/10 -1 means reciprocal 1 over 10 1/10
0.01 = 10^-2 = 1/10 x 1/ 10 = 1/100

2 x 10² = 2 x (10²) 10² = 10 x 10
            = 200

3 x 10^-3 = 3 x 0.001

(3 x 10²) (2 x 10³) =

3 ee or exp 2 X 2 ee or exp 3 =

(4 x 10^-4) ( 6 x 10^-3) =

4 ee or exp 4 +/- X 6 ee or exp 3 +/- =

0.0075 = 7.5 x 10^?
0.0000006 = 6 x 10^?
8,000,000,000 = 8 x 10^?

MEASUREMENTS

A great deal of the research in chemistry depends upon measurement. We have little or no difficulty in dealing with measurement for every day occurrences. However, we tend to think of science measurement as different and difficult. We buy a pound of grapes, a gallon of milk or a yard of cloth effortlessly. Pounds, gallons and yards are the terms used in the English system. In scientific measurements the Metric system of kilograms, liters, and meters is used.

There has been a push for American consumers to go to the metric system. We now have liter containers of drinks. The transition to the metric system is going very slowly simply because people are used to using the English system. Is the English system any better than the metric system? No! In fact the English system is much more difficult to use.

1 fluid ounce of water = 1 ounce of water *

* For other liquids 1 fluid ounce is not the same as ounce, depending on the density of the liquid. This is covered in the section on density.

1 quart = 0.946 Liter (946 milliliters)

MILLI, MICRO, NANO, PICO - 3, 6, 9, 12

In chemistry we will be working with the metric system.

Deci = -1                                     1 dg = 1 x 10-1 g                                         1 x 101 dg = 1 g

Centi = -2                                    1 cg = 1 x 10-2 g                                         1 x 102 cg = 1 g

Milli = -3                                      1 mg = 1 x 10-3 g                                        1 x 103 mg = 1 g

Micro = -6                                   1 ug = 1 x 10 -6 g                                        1 x 106 ug = 1 g

Nano = -9                                    1 ng = 1 x 10-9 g                                         1 x 109 ng = 1 g

Pico = -12                                    1 pg = 1 x 10 -12 g                                      1 x1012 pg = 1 g

1 x 10³ mg                         1 g
1 g                                 1 x 10³ mg

Kilo = 10³ = 1000                    1000 g = 1 Kg                      1 x 10³ m = 1 Km

Write the conversion equations for micrograms, nanograms, and picograms with grams.

HOW TO DO CONVERSION PROBLEMS - DIMENSIONAL ANALYSIS

Relax! The Jackson approach to math is to use it as a tool to get at something else. It is not a philosophical approach. It is one of pigeon holes and formulas. Stuff µ>em in or plug µ>em in.

In math generally you are given something and asked to find something else from what you were given. To set up a problem we divide it into two sections:

WHAT YOU HAVE and WHAT YOU ARE LOOKING FOR

Problem: How many milligrams are in 8.6 grams?

A) Write what you have

8.6 grams

B) Write what you are looking for

8.6 grams = milligrams

C) Scan your mind to see if you have anything relating to grams and milligrams. (Hint: milli, micro, nano, pico)

1 gram = 1 x 10³ milligrams 1 gram 1 x 10³mg

1 x 10³ mg 1 gram

D) Write down the conversion factors for mg and g.

( 8.6 g) ( 1 g      )     = ______mg
               1 x 10³ mg

 

( 8.6 g) ( 1 x 10³ mg )      =  ______mg
                    1 g

Which one are you going to pick?

If you pick the first one, nothing cancels out on the left and you have g²/mg
                   so g²/mg does not equal mg on the right.

If you pick the second one, the grams cancel out and you have - mg = mg

Problem: How many nanograms are present in 5.2 milligrams?

A) 5.2 mg

B) 5.2 mg                                              = __________ng

C) Mind scan

1 g 1 x 10³ mg                       1 g 1 x 10⁹ ng
1 x 10³ mg 1 g                       1 x 10⁹ ng 1 g

D) We want to cancel out the milligrams, so we need the conversion expression where milligrams is on the bottom.

5.2 mg     1 g                                         = __________ng
           1 x 10³ mg

E) The milligrams have cancelled out. Now we need to cancel out the grams. Since grams is on the top, weµ=ll need the conversion expression where grams is on the bottom.

5.2 mg  1 g                     1 x 10⁹ ng                           = __________ng
         1 x                        10³ mg 1 g

MORE PROBLEMS

Convert:

1) 35 mg to pg

2) 7.2 kg to mg

3) 86 pg to ug

4) 18 dl to mL

5) 32 mg to g

6) 63 mL to L

7) 13 kg to mg

8) 2.5 x 10⁴ ug to pg

9) 62 L to mL

10) 5.7 x 10^-2 uL to L

11) 6.7 x 10^-4mg to g

12) The yellow light given off by a sodium lamp has a wavelength of 589 nm. Express than in a) Angstroms and b) meters. ( 1 x 10¹⁰ Angstroms = 1 meter)

13) The radius of a sodium atom (Na) is 1.23 Angstroms. Express that in meters.

14) A 5 mL sample of water has a mass of 5 grams. What is the mass of 1 liter of water?

15) The recommended dosage of a drug is 2 mg for each kilogram of body weight. How many milligrams would be needed for a a) 60 lb child b) 120 lb woman c) 210 lb man

16) Give the weight (mass) in Kg for the following body weights of individuals

a) 45 lbs

b) 220 lbs

c) 125 lbs

d) 310 lbs

e) 70 lbs

f) 105 lbs

g) 180 lbs

i) 20 lbs

j) 260 lbs

k) 165 lbs

17) Given the following dosage - 0.2 mg/Kg body weight. How many milligrams of the drug would be needed for individuals with the following weights?

a) 145 lbs

b) 275 lbs

c) 80 lbs

d) 190 lbs

e) 110 lbs

f) 50 lbs

g) 135 lbs

h) 200 lbs

i) 230 lbs

18) The label on a drug vial read "25 µg/mL"  How many milliliters would be needed for the following dosages?

a) 10 µg

b) 150 µg

c) 0.2 mg

d) 0.5 mg

e) 80 µg

19) Convert:

a) 19 mg = ________µg

b) 0.2 g = ______mg

c) 8 µg = ______mg

d) 1.2 mg = _____µg

e) 1.2 mg = ______g

f) 1.2 µg = _______ g

g) 2 Kg = _______g

h) 2 mg = ______Kg

i) 6 L = ________mL

j) 2.5 L = _______dL

k) 250 dL = _______L

m) 250 dL = ______mL

n) 15 mL = _______L

o) 1 dL = _______mL

p) 800 mL = ________L

20. A multi-dose vial had the concentration 2 mg/mL. The adult dosage was 2 mg. What would that be in mg/kg for a) 120 lb woman b) 185 lb man?

Temperature

Fahrenheit: Water boils at 212^oF. Water freezes at 32^oF.

Celsius: Water boils at 100^oC. Water freezes at 0^oC. (centigrade)

Kelvin: Water boils at 373^oK. Water freezes at 273^oK.

O^oK is absolute zero - as cold as you can go. No molecular activity at O^oK.

Formulas: ^oK = ^oC + 273^o

1.8C = F^o - 32

NOTE: Always do the math of the brackets first.

Problems:

1. In the lab a reaction took place at -20^oC. What was that on the Kelvin scale?

2. 200^oK = ________________^oC

3. 98.6^oF = _______________^oC

4. 54^oC = _________________^oF

5. ______ A sustained body temperature of 107^oF is fatal. What is that on the Celsius scale?

Density

D = M/V                                      D = density (g/ml)
                                                    M = mass (g)
                                                    V = volume (ml) Remember 1 mL is equal to 1 cm³ or cc.

Density is a relative term, meaning how "heavy" per unit size something is.

Example: Two people weigh 185 pounds. One is "solid" a football player. His weight is in muscle. His volume is not all that big. Another is "sloppy" heavy. His weight is in a gut. His volume is greater.

Problems:

1. An object has a mass of 100 g and a volume of 50 cm³ (think of cm³ as ml). What is the density?

D = M/V

2. The density of an object is 4.0 g/ml and it weighs 1.00 kg. What is its volume? (convert kg to g first)

D = M/V

3. A steel ball has a density 7.2 g/cm³ and a volume of 5.0 liters. What is its weight? (Convert liters to mL first)

D = M/V

How can we measure volumes?

In a graduated cylinder that has 50 ml water, we put a steel ball in, the water now goes up to 60 ml.

water + ball       = 60 mL
             water   = 50   
             ball      = 10 mL

The volume of the steel ball is 10 ml.

Def: The ratio of the density of a particular substance compared to water at 4^oC.

1 g water has a volume of 1 cm³ (1 ml) What is the volume of 50 grams of water?

D = M/V
D = 1 g/l ml
D_H2O = 1 g/ml

Specific gravity does not have units - it is a ratio. The density of water is 1 g/ml. The specific gravity of water is 1.

Problems:

1. An object has a density of 7.2 g/ml, determine its specific gravity.

Sp. gravity = Density of unknown
                      Density of water

2. The specific gravity of water is 1. What volume is occupied by 500 g?  (Since sp. gravity H₂O = 1, density = 1.0 g/ml)

D = M/V

3. An object weighing 250 g has a volume of 200 ml. Calculate its specific gravity.

CALORIES

A calorie is a unit of heat energy. One calorie is the amount of energy required to heat 1 gram of water 1^oC. A kilocalorie is 1000 calories. A kilocalorie is represented by a capital 'C'. The calorie people use when referring to food calories, it is a kilocalorie.

Specific heat is the amount of heat required to raise 1 gram of a substance 1^o Celsius.

This can be given for either calories or joules in charts..

Specific heat of water 1 cal/g^oC

The lower the value for specific heat, the easier for the substance to heat up. Insulators will have high specific heats.

Δ means change

SpH means specific heat

temperature is given in Celsius

It takes energy for matter to changes phases. For a solid to change to a liquid, it takes heat energy, either referred to as calories or joules. These values are given in charts.

Heat of fusion for water ΔH_fus = 80 cal/g

To go from the liquid to the gas phase, it requires energy. This is referred to as the heat of vaporation.

calories = (mass) (Δ H_vap)

Heat of vaporation of water ΔH_vap = 540 cal/g

1) -5^oC ice to 0^oC ice

2) 0^o C ice to 0^o C water

3) 0^oC water to 100^oC water

4) 100^oC water to 100^oC steam

More problems:

1. Convert a) 145 lbs to kg;     b) 47 mg to g;     c) 47 mg to ng;     d) 47 mt to m g

2. On the bottle for drug, it read 0.5 mg/Kg.  How many mg would be needed for

a) 50 lb child

b) 105 lb woman

c) 190 lb man

3. On a drug vial, it read 2 mg/mL. How many mL would be needed for

a) 6 mg

b) 2 mg

Thursday, January 03, 2008 09:48:35 AM