OLLU
What are the number of atoms in 22.4dm of chlorine gas at S. T.P:
A. 10
B. 20
C 6.02 x 1023
- 1.2 x 1024
3

C. 6 E23 atoms Cl2

Explanation:

S.T.P:

∴ T = 25°C ≅ 298 K

∴ P = 1 atm

ideal gas:

∴ R = 0.082 atm.L/K.mol

∴ V = 22.4 dm³ = 22.4 L

⇒ mol (n) = PV/RT

⇒ n Cl2(g) = ((1 atm)(22.4 L)/(0.082 atm.L/K.mol)(298 K))

⇒ n Cl2(g) = 0.9166 mol

⇒ atoms Cl2(g) = (0.9166 mol)*(6.022 E23 atoms/mol)

⇒ atoms Cl2(g) = 5.52 E23 atoms ≅ 6 E23 atoms

chemical changes occur when a substance combines with another to form a new substance, called chemical synthesis or, alternatively, chemical decomposition into two or more different substances. these processes are called chemical reactions and, in general, are not reversible except by further chemical reactions. some reactions produce heat and are called exothermic reactions and others may require heat to enable the reaction to occur, which are called endothermic reactions. understanding chemical changes is a major part of the science of chemistry.