Chemistry: a science that deals with matter; its structure, its composition, and transformation or changes.

It is very important in allied health to be able to measure physical dimensions pertaining to matter.

Matter is anything that has mass and occupies space (volume).

Mass is defined as the quantity of matter in an object; does not change with location even if it is in the moon or in any weightless condition.

Weight is a measure of gravitational attraction on an object; it varies with location. An astronaut with a mass of 200 lbs has the same mass of 200 lbs in the moon; the weight, however, would be less. Compare gravitational attraction in the moon and on the earth.

**1.1 Units of Measurement
**

Metric System is used almost throughout the world, with the exception of a few countries, by scientists and allied health professionals. In 1960, a modification of the metric system, Systeme Internationale (SI), was adopted . In this textbook, metric system and some SI units are used.

Table 1.1 shows comparison of the metric and SI units.

Measurements Metric SI

Length Meter (m) Meter (m)

Volume
Liter (L)
cubic meter (m^{3})

Mass Gram (g) Kilogram (kg)

Time Second (s) Second (s)

Temperature
Celsius (^{o}C)
Kelvin (K)

Temperature measures how hot or how cold an object is. It is not the same as heat.

*How to use your text book:*

Each topic is followed by
CONCEPT CHECK, SAMPLE PROBLEM, Study Check, and Questions and Problems.
Answers to Study check are found at the end of the chapter. Also, answers to **
red numbered problems** are found at the back of the chapter. **BE SURE TO DO
EACH CONCEPT, SAMPLE PROBLEMS, and STUDY CHECKS for practice. **

**
1.2 Scientific Notation**: Exponential Form.

Large or small numbers can be converted into scientific notation by moving decimal. The number should be written as coefficient with a value between 1 - 10 and multiplied by 10 raised to some power or exponent.

** The exponent represents how many places the decimal has been moved.

**(+) power or exponent means decimal has been moved to the left
for number larger than 1. Table 1.2**

10000 = 1 x 10** ^{4}
**= 10 x 10 x 10 x 10

7550000 = 7.55 x 10^{6}

**(-) power or exponent means decimal has been moved to the right for number
less than 1.**

0.00001 = 1 x 10** ^{-5}** = 1/10 x 1/10 x 1/10 x
1/10 x 1/10

0.0000755 = 7.55 x 10^{-5}

***Do Sample problems 1.2, Study Check, and Questions and Problems (p. 21)

Make sure you know how to use your calculator with scientific notation. (p. 20) or go to the math lab at the library.

**1.3 Measured
Numbers and Significant Figure**

Numerical values obtained from any
**measurement** are never exact because
of some degree of uncertainty due to the precision of the equipment and
the skill of the operator.

Significant figures (SF) in **measurement** include all the digits (definitely
known) and one estimated digit.

Example: 355.8**7** ; **7**
is an estimated digit

Significant Figures in **Measured Numbers** and rules of
counting Significant Figures (SF).

Determining the number of significant figures:

1. A number is a ** significant figure **if it is:

(a) **Non** zero, therefore, digits 1 - 9 are significant : Ex. 25g
**2SF**; 1.88cm
** 3SF **

(b) **Zero** between nonzero digits (captive zeros):
Ex.
205L **3SF**; 10.88kg
** 4SF**

(c) A **zero at the end of a decimal**
: Ex.
25.**0**m **3SF ** 151.**00 **mg ** 5SF
**

** **(d) Any digit in the coefficient of a number

written in scientific notation Ex.
**2.50** x 10^{5} mm **3SF
2.1** x 10^{-3} lb **2SF**

2. A zero is __
not significant __ if it is

(a) At beginning of decimal number not significant
0.**0**68mg **2SF**
0.**0000**2 kg 1SF

(b) Used as a placeholder in a large number **without a decimal **or trailing zeros
1200m **2SF**

135 000mL **3SF**

Exact Numbers
are **NOT** measured; they are obtained by **counting** or from **defined
equalities in the same measuring system**; they **do not affect the number**
of SF in a calculated answer.

Counted numbers U.S. System Metric System

15 oranges 1 ft = 12 in. 1 m = 10 dm

25 persons 1 lb = 16 oz. 1kg = 1000 g

**1.4 Significant Figures in
Calculations**

** **a)
Rounding off:

1. If the
first digit to be dropped is **4 or less,** then it and all the following are
dropped from the number.

Two SF Three SF

Example:
5.21**4**84 round off to
5.2
5.21

2. If the first
digit to be dropped is **5 or greater**, then the last retained digit of the
number is increased by **1.**

Example:
5.214**8**4 round off to **four** SF 5.21**5**

**
Do Concept 1.4; Sample problem 1.4, and Study Check**

b) Multiplication and Division: the final answer will have the same number of SF as the measurement with the fewest SF.

Ex. 2.34(3SF) x 0.032 **(2SF)** = 0.07488 (calculator) = 0.075 **
(2SF) rounded to 2SF**

**
**2.34/0.0**32** = 73.125 (calculator) = 73 **(2SF) rounded to **2SF

c) Addition and Subtraction: the answer is written so that it has the same
number of decimal places as the measurement with the** fewest** decimal
places.

Examples: 1.2 **(one
decimal place)** + 1.22 (2 decimal place) = 2.42 (calculator) = 2.4 **(one
decimal place) rounded to one decimal place **

**
** **55(ones place) **- 2.8 (one decimal) = 52.2 (calculator) = **52
rounded to ones place** ** **

Do Concepts, Sample problems, and Study Checks.

d) Adding Significant Zeros: Significant zeros, sometimes, may be written to correct the number of SF displayed by the calculator.

Example: 55.0/**1.1** = 5
(calculator gives **one** SF; from the calculation answer should have **2SF**;
therefore the correct answer is written as **5.0(2SF)**

__ __

**1.5 Prefixes and Equalities**

**
** Table 1.6 Metric and SI Prefixes

**Common Prefixes
that increase the size of the unit: **
gram (m), Liter (L), meter (m), and seconds (s)

Prefix Symbol Numerical Value Scientific Notation Equality

giga
G
1000 000 000
10^{9}
1Gm = 10^{9} m

mega
M
1000 000
10^{6}
1Mg = 10^{6}

kilo
k
1000
10^{3 }
kL = 10^{3}L

*Common Prefixes that decrease the size of the
unit:**gram (m), Liter (L), meter (m), and
seconds (s) ** *

Prefix Symbol Numerical Value Scientific Notation Equality

deci
d
0.1
10^{-1}
1dL = 10^{-1}L

*1L =10 ^{1}dL*

centi
c
0.01
10^{-2 }
1cm = 10^{-2} m

* 1m = 100 cm*

milli
m
0.001
10^{-3 }
1mg = 10^{-3} g

*1g = 1000 mg*

micro
µ
0.000 001
10^{-6}
1µm = 10^{-6} m

*1m = 10 ^{6} µ m*

Some equalities:

1 meter = 100 cm 1dL = 100 mL

1L = 10dL
1g = 10^{6} µg

1L = 1000 mL

**1.6 Writing Conversion Factors**

** a) Table 1.9 Some Common Equalities**

**Quantity
US
Metric (SI)
Metric-US**

Length 1ft = 12 in. 1km = 1000 m 2.54 cm = 1 in.

1 yard = 3 ft 1m = 1000 mm 1m = 39.4 in

1 mile = 5280 ft 1cm = 10 mm 1 km = 0.621 mi

____________________________________________________________________________________________________________________

Volume 1qt = 4 cups 1L = 1000 mL 946 mL = 1 qt

1 qt = 2 pt 1 dL = 100 mL 1 L = 1.06 qt

1 gallon = 4 qt 1 mL = 1cm^{3}

____________________________________________________________________________________________________________________

Mass 1 lb = 16 oz 1 kg = 1000 g 1 kg = 2.20 lb

1 g = 1000 mg 454 g = 1 lb

_____________________________________________________________________________________________________________________

Time 1 hr = 60 min

1 min = 60 s

____________________________________________________________________________________________________________________

**b) Examples of conversion factors**

Equality Conversion factor

1 m = 100 cm 1m/100 cm and 100cm/1m

1 kg = 2.20 lb 1 kg/2.20 lb and 2.20/1kg

**c) How to set up problems using two or more
conversion factors: **

Rules to follow in unit conversion:

(a) Write down the known or given quantity including the unit.

(b) Write down the conversion factors in fraction form.

(c) Multiply (a) by the conversion factor written in fraction such that units cancel.

(d) Determine the number of significant figures in the answer.

Examples:

How many mL are there in 1.75 gallons? **(Two steps)** Table 1.9

(a) Given: 1.75 gallons (Ans. 6620 mL (3SF)

(b) conversion factors:

1 gallon/4qt and 4qt/1gal

(c) Multiply (a) by conversion factor so that units cancel:

Equalities: 1 gal = 4 qt; 1qt = 946 mL

A 15.0 km distance is how many miles long?
(Ans. 9.32 mi)

Equality: 1 km = 0.621 mi

How many cm/second are there in 120 miles/minute?
(ans. 3.2 x 10^{ 5} cm/s )

Equalities: 1 km = 0.621 mi; 1km = 1000 m; 1 m = 100 cm; 1 min = 60 seconds

**1.7
Practice problems**: PRACTICE ** **

**1.8 Density
(mass/volume): **

It is a comparison of the mass of an object and its volume.

In metric
system, the densities of solids and liquids are expressed as gram per cubic
centimeter (g/cm ^{3}) or gram per millimeter (g/mL); gases are
expressed as grams per liter (g/L).

Example problems:

Determine the density in g/mL of a liquid that has a mass of 61.5 grams and a
volume 73.2 mL. **(Ans.0.840 g/mL, 3SF) **

A copper sample has a mass of 44.65 g and a volume of 5.0 mL.
What is the density of of copper? **(Ans. 8.9 g/mL, 2 SF) **

**Density of Solids: **

Weigh the solid to get its mass. Calculate the volume of the solid by volume displacement because a completely submerged object displaces a volume of liquid that is equal to its volume.

Problem example:

A metal has a mass of 226 g. When the metal is placed in a graduated cylinder containing 200.0 mL of water, the water level rises to 220.0 ml. What is the density of of the metal in g/mL?

Volume of the metal: 220.0 mL - 200.0 mL = 20.0 mL

Mass of the metal: 226 g

Density =m/v = 226g /20.0
mL = **11.3 g/mL (3SF)**

Do the study checks 1.15 on p. 44 and study check 1.16 p. 44

Do sample problem 1.17 p.46

**Specific Gravity (spgr): **It is a ratio between the density of
a substance and the density of water which id 1.00g/mL at 4^{o}C.
An instrument, a hydrometer, is used to measure the specific gravity of
fluid (battery fluids, urine, etc)

Specific gravity = density of substance /density of water; if units cancel (NO UNIT)

If the hydrometer reading is 1.006, what is the density of the liquid?

Problem:

John took 2.0
teaspoons (tsp) of cough syrup with a specific gravity of 1.20. If there
is 5.0 mL in a teaspoon, what is mass in grams of the syrup? **(Ans.12
g)**

Equalities (conversion factor):

1tsp=5.0 mL ; 1mL= 1.20g