The scientific method is a set of procedures used to develop explanations of natural phenomena and possibly to predict additional phenomena. For example, The average temperature of seawater increases, the seawater will become less dense, its volume will increase, and sea level will rise even if no continental ice melts.

1. Matter
Dr. K. Shahzad Baig
MUN-Canada
Petrucci, et al. 2011. General Chemistry: Principles and Modern Applications. Pearson Canada Inc., Toronto, Ontario.
Tro, N.J. 2010. Principles of Chemistry. : A molecular approach. Pearson Education, Inc.

2. The Scientific Method
The scientific method is a set of procedures used to develop explanations of natural
phenomena and possibly to predict additional phenomena.
The four basic stages of the scientific method are
1. gathering data through observations and experiments;
2. reducing the data to simple verbal or mathematical expressions known as natural laws;
3. offering a plausible explanation of the data through a hypothesis;
4. testing the hypothesis to make a theory that explains the hypothesis

3. Matter
Matter is defined as anything that occupies mass, and display space, possesses
inertia.
Composition refers to the component parts of a sample of matter and their
relative proportions.
Atom is the basic building blocks of matter
Element
Matter that is composed of a collection of a single type of atom is known as an element.
Compound
Matter composed of two or more elements is known as a compound
Molecule is the smallest entity of a compound having the same proportions of the
constituent atoms as does the compound as a whole

4. Extensive properties depend on the amount of matter in a sample e.g. mass , volume
Intensive property is independent of the amount of matter sampled, e.g. density
In making a series of measurements,
the degree to which the measurements agree with one another is known as
the precision of the measurement
the degree to which the measurement agrees with the actual value is referred
to as the accuracy of the measurement.
The significant figures of a number are the digits that contribute to its measurement
resolution. This includes all digits except: All leading zeros

5. SI Base Quantities
Physical quantity Unim
Length meter
Mass kilogram
Time second
Temperature kelvin
Amount of
substance
mole
Electric current ampere
Luminous intensity candela

7. Density and Percent Composition:
Density is the ratio of mass to volume.
𝐷𝑒𝑛𝑠𝑖𝑡𝑦 𝑑 =
𝑀𝑎𝑠𝑠 (𝑚)
𝑉𝑜𝑙𝑢𝑚𝑒 (𝑣)
=
𝑔
𝑐𝑚3
Density is a function of temperature because volume varies with temperature, whereas
mass remains constant
The mass of 1.000 L of water at 4 °C = 1.000 kg.
The density of water at 4 °C = 1000 g/1000 mL = 1.0 g/mL
The density of water at 20 °C = ? g/ ? mL = 0.9982 g/mL
the average temperature of seawater increases, the seawater will become less dense, its
volume will increase, and sea level will rise even if no continental ice melts.

8. Example
A cube of osmium 1.000 cm on edge weighs 22.59 g. The density of osmium (the densest
of the elements) is 22.59 g/m3. What would be the mass of a cube of osmium that is 1.25
in. on edge ( 1 in = 2.54 cm)
𝑀𝑎𝑠𝑠 𝑜𝑓 𝑂𝑠𝑚𝑖𝑢𝑚 𝑠𝑎𝑚𝑝𝑙𝑒 = 𝑔 = 1.25 𝑖𝑛 𝑥
2.54 𝑐𝑚
1 𝑖𝑛
3
𝑥
22.59 𝑔 𝑜𝑠𝑠𝑚𝑖𝑢𝑚
1𝑐𝑚3
=
= 723 g ossmium
𝑀𝑎𝑠𝑠 = 𝑉𝑜𝑙𝑢𝑚𝑒 𝑥 𝐷𝑒𝑛𝑠𝑖𝑡𝑦
𝐷𝑒𝑛𝑠𝑖𝑡𝑦 𝑑 =
𝑀𝑎𝑠𝑠 (𝑚)
𝑉𝑜𝑙𝑢𝑚𝑒 (𝑣)
=
𝑔
𝑐𝑚3

9. Example
𝐷𝑒𝑛𝑠𝑖𝑡𝑦 𝑑 =
𝑀𝑎𝑠𝑠 (𝑚)
𝑉𝑜𝑙𝑢𝑚𝑒 (𝑣)
=
𝑔
𝑐𝑚3
At 25 °C the density of mercury, the only metal that is liquid at this temperature, is 13.5
g/cm 3. What is the volume, in mL, of 1.000 kg of mercury at 25 °C.
𝑉𝑜𝑙𝑢𝑚𝑒 𝑣 = 𝑀𝑎𝑠𝑠 𝑚 𝑥
1
𝐷𝑒𝑛𝑠𝑖𝑡𝑦 (𝑑)
= ? 𝑚𝐿
𝑚𝐿, 𝐻𝑔 = 1.000 𝑘𝑔 𝑥
1000 𝑔
1 𝑘𝑔
𝑥
1 𝑚𝐿 𝐻𝑔
13.5 𝑔
= 74.1 𝑚𝐿 𝐻𝑔

10. Example 1-2 Relating Mass, Volume, and Density
The stainless steel in the solid cylindrical rod pictured below has a density of 7.75 g/cm3. If
we want a 1.00 kg mass of this rod, how long a section must we cut off?
𝑑 =
(𝑚)
(𝑣)
𝑣 = 𝑚 𝑥
1
𝑑
𝑣 = 1.00 𝑘𝑔 𝑥
1000 𝑔
1 𝑘𝑔
𝑥
1 𝑐𝑚3
7.75 𝑔
= ? 𝑐𝑚3
𝑣 = 𝜋 𝑟2 𝐿
𝐿 =
𝑣
𝜋𝑟2
𝐿 =
129 𝑐𝑚3
3.1416 𝑥 0.500 𝑖𝑛 𝑥
2.54 𝑐𝑚
1 𝑖𝑛
2
= 25.5 𝑐𝑚3

11. PRACTICE EXAMPLE A:
To determine the density of trichloroethylene, a liquid used to degrease electronic
components, a flask is first weighed empty (108.6 g). It is then filled with 125 mL of the
trichloroethylene to give a total mass of 291.4 g. What is the density of trichloroethylene
in grams per milliliter?
PRACTICE EXAMPLE B:
Suppose that instead of using the cylindrical rod of Example 1-2 to prepare a 1.000 kg
mass we were to use a solid spherical ball of copper (d = 8.96 g/cm3). What must be the
radius of this ball?

12. Example 1-3
Determining the Density of an Irregularly Shaped Solid
A chunk of coal is weighed twice while suspended from a spring scale. When the coal is
suspended in air, the scale registers 156 g; when the coal is suspended underwater at 20 °C,
the scale registers 59 g. What is the density of the coal? The density of water at 20 °C is
0.9982 g cm3
.
If we use mwater to denote the mass of displaced water, then the volume of the displaced
water is calculated as follows:
𝑣 =
𝑚𝑎𝑠𝑠 𝑤𝑎𝑡𝑒𝑟
𝑑
= ? 𝑐𝑚3
=
156 𝑔 − 59 𝑔
0.9982 𝑔
𝑐𝑚3
= 97 𝑐𝑚3
The volume of the chunk of coal is the same as the volume of displaced water.
𝑑 =
156 𝑔
97 𝑐𝑚3
= ? = 1.6 g / cm 3

13. Alternate way to solve
𝑣 =
𝑚𝑎𝑠𝑠 𝑤𝑎𝑡𝑒𝑟
𝑑
= ? 𝑐𝑚3
𝑑 =
𝑀𝑎𝑠𝑠 𝑔
𝑉𝑜𝑙𝑢𝑚𝑒 𝑐𝑚3
= ?
𝐷𝑒𝑛𝑠𝑖𝑡𝑦 𝑜𝑓 𝑂𝑏𝑗𝑒𝑐𝑡
𝐷𝑒𝑛𝑠𝑖𝑡𝑦 𝑜𝑓 𝑤𝑎𝑡𝑒𝑟
=
𝑊𝑒𝑖𝑔ℎ𝑡 𝑖𝑛 𝑤𝑎𝑡𝑒𝑟
𝑊𝑒𝑖𝑔ℎ𝑡 𝑖𝑛 𝑎𝑖𝑟 − 𝑊𝑒𝑖𝑔ℎ𝑡 𝑖𝑛 𝑤𝑎𝑡𝑒𝑟

14. PRACTICE EXAMPLE A:
A graduated cylinder contains 33.8 mL of water. A stone with a mass of 28.4 g is
placed in the cylinder and the water level rises to 44.1 mL. What is the density of the
stone?

15. EXAMPLE 1-4
Using Percent Composition as a Conversion Factor
A 75 g sample of sodium chloride (table salt) is to be produced by evaporating to
dryness a quantity of seawater containing 3.5% sodium chloride by mass. What volume
of seawater, in liters, must be taken for this purpose? Assume a density of 1.03 g/mL for
seawater
𝐷𝑒𝑛𝑠𝑖𝑡𝑦 𝑑 =
𝑀𝑎𝑠𝑠 (𝑚)
𝑉𝑜𝑙𝑢𝑚𝑒 (𝑣)
=
𝑔
𝑐𝑚3
𝑉𝑜𝑙𝑢𝑚𝑒 𝑣 = [𝑀𝑎𝑠𝑠 𝑚 ] 𝑥
1
[𝐷𝑒𝑛𝑠𝑖𝑡𝑦 𝑑 ]
= ? 𝑚𝑙
𝐿 𝑆𝑒𝑎𝑤𝑎𝑡𝑒𝑟 𝑣 = 75 𝑔 𝑁𝑎𝐶𝑙
100 𝑔 𝑆𝑒𝑎𝑤𝑎𝑡𝑒𝑟
3.5 𝑔 𝑁𝑎𝐶𝑙
𝑥
1 𝑚𝐿 𝑆𝑒𝑎𝑤𝑎𝑡𝑒𝑟
1.03 𝑔 𝑆𝑒𝑎𝑤𝑎𝑡𝑒𝑟
𝑥
1 𝐿 𝑆𝑒𝑎𝑤𝑎𝑡𝑒𝑟
1000 𝑚𝐿 𝑆𝑒𝑎𝑤𝑎𝑡𝑒𝑟
= 2.1 𝐿 𝑆𝑒𝑎𝑤𝑎𝑡𝑒𝑟

16. PRACTICE EXAMPLE A:
How many kilograms of ethanol are present in 25 L of a gasohol solution that is 90%
gasoline to 10% ethanol by mass? The density of gasohol is 0.71 g/mL
PRACTICE EXAMPLE B:
Common rubbing alcohol is a solution of 70.0% isopropyl alcohol by mass in water. If a
25.0 mL sample of rubbing alcohol contains 15.0 g of isopropyl alcohol, what is the
density of the rubbing alcohol?