Properties of matter (mass, volume, density)

Measurements and units

Measurements - Units of measurement:

For the length we have the measure, for the mass we have the balance (scale), for the volume the volumetric cylinder, for the temperature the thermometer etc. (picture 1.1).

1.1

The International System of Units (SI):

The SI system contains 7 fundamental quantities with their characteristic units (Table 1.2). All other quantities used are derivatives of these fundamental quantities. Despite the efforts of scientists for the full dominance of the International System of Units, other units are still used today, e.g. the pressure of a gas is usually expressed in atm and not in pascal - Pa (N / m2, where N = Kg.m / s2).

1.2

Many times we use multiples and multiples of the basic units (easy to use units) (Figure 1.3)

1.3

The measurements we most often use in chemistry include the quantities mass, volume, density and temperature.

Mass and Weight: Mass and weight

sizes are different. A body has the same mass in all parts of the earth, but it has a different weight from place to place.

• Weight is the gravitational force exerted on the body by the earth's gravitational field.

• Mass is the measure of a body's resistance to changing its velocity and expresses the amount of matter contained in a substance.

Weight measuring instruments: the dynamometer

Mass measuring instruments:

Units of measurement:

Weight: N

Mass: Kg

Volume: It is the space occupied by a body.

Volume measurement: in the chemical laboratory it is done with the help of volumetric instruments such as the pipette, the pipette, the volumetric cylinder, the volumetric flask, etc. (figure 1.3)

1.3

Density (p):

The density is defined as the quotient of the mass to the corresponding volume at constant pressure (in the case of gas) and temperature conditions.

Type:ρ = m / V

The unit of density (derivative size) in SI is Kg / m3.