(Chemistry Ch-1) 2. Properties of Matter

• Physical properties
  • Properties which can be measured or observed without changing the identity or composition of the substance
  • Example − Colour, odour, melting point, boiling point, density, etc.

• Chemical Properties
  • Properties in which chemical change in the substance takes place
  • Examples − Characteristic reactions of different substances such as acidity, basicity, combustibility, reactions with other elements and compounds
  • Quantitative properties can be of the following types:

Measurement of properties

• Systems of Measurement
  • English system
  • Metric system
  • International system of units (SI)

• The International System of Units (SI)
• Seven base units

Base Physical Quantity	Symbol for Quantity	Name of SI Unit	Symbol for SI Unit
Length Mass Time Electric current Temperature Amount of substance Luminous intensity	l m t I T n lv	metre kilogram second ampere kelvin mole candela	m kg s A K mol cd

• Definitions of SI base units
  
  

Unit of length	metre	The metre is the length of the path travelled by light in vacuum during a time interval of 1/299 792 458 of a second.
Unit of mass	kilogram	The kilogram is the unit of mass; it is equal to the mass of the international prototype of the kilogram.
Unit of time	second	The second is the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom.
Unit of electric current	ampere	The ampere is that constant current, which if maintained in two straight parallel conductors of infinite length of negligible circular cross-section and placed 1 metre apart in vacuum, would produce a force equal to 2 × 10−7 Newton per metre of length between these conductors.
Unit of thermodynamic temperature	kelvin	The kelvin, unit of thermodynamic temperature, is the fraction 1/273.16 of the thermodynamic temperature of the triple point of water.
Unit of amount of substance	mole	1. The mole is the amount of substance of a system, which contains as many elementary entities as there are atoms in 0.012 kilogram of carbon-12; its symbol is “mol.” 2. When the mole is used, the elementary entities must be specified and these may be atoms, molecules, ions, electrons, other particles, or specified groups of such particles.
Unit of luminous intensity	candela	The candela is the luminous intensity (in a given direction) of a source that emits monochromatic radiation of frequency 540 × 1012 hertz and that has a radiant intensity in that direction of 1/683 watt per steradian.

• Prefixes used to indicate the multiples or submultiples of a unit.

Multiple	Prefix	Symbol
10−24	yocto	y
10−21	zepto	z
10−18	atto	a
10−15	femto	f
10−12	pico	p
10−9	nano	n
10−6	micro	μ
10−3	milli	m
10−2	centi	c
10−1	deci	d
10	deca	da
102	hecto	h
103	kilo	k
106	mega	M
109	giga	G
1012	tera	T
1015	peta	P
1018	exa	E
1021	zeta	Z
1024	yotta	Y

• Mass and Weight

Mass	Weight
Amount of matter present in an object	Force exerted on an object by gravity
Constant, irrespective of the place	Vary from place to place due to change in gravity

• Mass can be determined accurately by using an analytical balance.

• SI unit of mass = Kilogram (kg)
• 1 kg = 1000 g = 10⁶ mg

• Volume

• Amount of space occupied by an object
• Has the units of (length)³
• SI unit = m³
• Often used units = dm³, L

1 dm³ = 1000 cm³

1 L = 1000 mL

• Litre is equal in size to dm³.

Millilitre is equal in size to cm³.

• Measuring devices − Burette, pipette, graduated cylinder, volumetric flask

• Density

• Amount of mass per unit volume

i.e., Density 

• SI unit of density =

 or kg m⁻³

• Often used unit = g cm⁻³

• Temperature

• Three scales − degree Celsius (°C)

degree Fahrenheit (°F)

kelvin (K)

• SI unit = Kelvin (K)
• Thermometers using different temperature scales

• Relation between °F and °C scale

°F =(°C) + 32

• Relation between K and °C scale

K = °C + 273.15

• Negative values of temperature are possible in °C scale, but not in °F and K scale.

Example The boiling point of water at sea level is 212 °F. What is its equivalent in Kelvin scale? Solution: To convert temperature from Fahrenheit scale into Kelvin scale, the following equations are used. °F =(°C) + 32 ⇒ °C = (°F − 32)/1.8 K = °C + 273.15 Converting °F into °C, °C = (212 − 32)/1.8 = 100 Therefore, the boiling point of water is 100°C converting °C into K. K = °C + 273.15 = 100 + 273.15 = 373.15 Hence, 212°F is equivalent to 373.15 K.