Properties of Matter and Their Measurement: Definition, Formula & Real-Life Applications

Physical properties, such as mass, volume, density, and melting point, can be measured without altering a substance's chemical identity. Chemical properties, like reactivity with acids or flammability, describe a substance's ability to undergo chemical changes. For example:

1. Physical: Density of water $=1\mathrm{g}/{\mathrm{c}\mathrm{m}}^3$ .

2. Chemical: Iron reacts with oxygen to form rust $\left({\mathrm{F}\mathrm{e}}_2{\mathrm{O}}_3\right)$ .

JEE questions may require identifying properties or using physical properties in calculations.

The International System of Units (SI) standardizes measurements with seven base units: meter (m, length), kilogram (kg, mass), second (s, time), kelvin (K, temperature), mole (mol, amount of substance), ampere (A, electric current), and candela (cd, luminous intensity). Derived units, like density ( $\mathrm{k}\mathrm{g}/{\mathrm{m}}^3$ ), are combinations of base units. SI prefixes (e.g., kilo- $={10}^3$ , milli- $={10}^{-3}$ ) simplify large/small quantities. JEE problems often involve unit conversions, such as converting ${\mathrm{c}\mathrm{m}}^3$ to ${\mathrm{m}}^3$ : $1{\mathrm{c}\mathrm{m}}^3={10}^{-6}{\mathrm{m}}^3$

\Mass is the amount of matter in a substance (kg), invariant across locations. Weight is the force exerted by gravity on mass (N), varying with gravitational field strength ( $g\approx 9.8\mathrm{m}/{\mathrm{s}}^2$ ).

$\text{Weight}=\text{mass}\times g$

Mass is measured using balances (e.g., analytical balance, precision to 0.0001 g ). Example: A 2 kg object has weight: $\text{Weight}=2\times 9.8=19.6\mathrm{N}$

JEE MAIN and NEET exam numericals test mass-weight distinctions and conversions.

Volume is the space occupied by matter ( ${\mathrm{m}}^3$ or L , where $1\mathrm{L}=1000{\mathrm{c}\mathrm{m}}^3$ ). It is measured using graduated cylinders, pipettes, or burettes, with precision to 0.1 mL for graduated cylinders. Conversion example: $500{\mathrm{c}\mathrm{m}}^3=0.5\mathrm{L}=0.0005{\mathrm{m}}^3$

JEE problems involve volume calculations in gas laws or solution chemistry.

Density is mass per unit volume ( $\mathrm{k}\mathrm{g}/{\mathrm{m}}^3$ or $\mathrm{g}/{\mathrm{c}\mathrm{m}}^3$ ): $\text{Density}=\frac{\text{mass}}{\text{volume}}$

Example: A 10 g object with volume $5{\mathrm{c}\mathrm{m}}^3$ has density: $\text{Density}=\frac{10}{5}=2\mathrm{g}/{\mathrm{c}\mathrm{m}}^3$

Density is temperature-dependent (liquids expand with heat).

JEE questions may require density-based calculations, such as determining mass from volume.

Temperature measures the degree of hotness or coldness, expressed in kelvin (K). Celsius ( ${}^{\circ }\mathrm{C}$ ) is also used, where: $\mathrm{K}={}^{\circ }\mathrm{C}+273.15$

Fahrenheit ( ${}^{\circ }\mathrm{F}$ ) conversion: ${}^{\circ }\mathrm{C}=\frac{5}{9}\left({}^{\circ }\mathrm{F}-32\right),\mathrm{}{}^{\circ }\mathrm{F}=\frac{9}{5}{}^{\circ }\mathrm{C}+32$

Example: ${25}^{\circ }\mathrm{C}=25+273.15=298.15\mathrm{K}$ . Thermometers (mercury or digital) measure temperature.

JEE problems involve temperature conversions in gas laws or thermochemistry.

Example 1: A metal block has a mass of 250 g and volume of $50{\mathrm{c}\mathrm{m}}^3$ . Calculate its density in $\mathrm{k}\mathrm{g}/{\mathrm{m}}^3$ . (JEE Main)

$\text{Density}=\frac{\text{mass}}{\text{volume}}=\frac{250}{50}=5\mathrm{g}/{\mathrm{c}\mathrm{m}}^3$

Convert units: $5\mathrm{g}/{\mathrm{c}\mathrm{m}}^3=5\times 1000=5000\mathrm{k}\mathrm{g}/{\mathrm{m}}^3\mathrm{}\left(1\mathrm{g}/{\mathrm{c}\mathrm{m}}^3=1000\mathrm{k}\mathrm{g}/{\mathrm{m}}^3\right)$

Example 2: Convert a gas volume of 2.5 L at $27{}^{\circ }\mathrm{C}$ to ${\mathrm{m}}^3$ at 300 K . (JEE Main) Volume in ${\mathrm{m}}^3$ :

Since volume is temperature-dependent $(V\propto T)$ : $V_2=V_1\times \frac{T_2}{T_1}=2.5\times {10}^{-3}\times \frac{300}{300}=2.5\times {10}^{-3}{\mathrm{m}}^3$

(Note: Same temperature implies no change, but JEE tests such conversions.)