Page 350 - General Knowledge

GENERAL KNOWLEDGE 2019

 Atoms of the same two or more given elements can combine in different simple whole
number ratios to form different compounds.
 In other words, two or more compounds can be composed of exactly the same elements, but
they have differing ratios of each element making them up.

Atomic Number
 The number of protons that are in a given atom.
 Atoms of the same element always have the same atomic number.
 Elements are arranged in the order of increasing atomic number on the Periodic Table.
Mass Number
The number of protons + the number of neutrons in a given atom of an element.
Isotopes
Isotopes are atoms of the same element, with the same number of protons and electrons,
but different numbers of neutrons in the nucleus.

3. GAS LAWS AND SOLUTIONS
 Gases are mostly empty space.
 It occupies containers uniformly and completely.
 Expands infinitely, diffuse and mix rapidly.
 Gases are mostly empty space. They are used to fill airbags to cushion the shock of an
impact.
 The chemical reaction that fills an airbag from the decomposition of sodium azide ( ).

 ( ) ( ) ( )

 Mathematical models explain the behavior of gases. This model includes one or more of
these quantities:
 P = Pressure (in units of atmospheres)
 V = Volume of the gas (in units of L)

 T = Temperature (in units of K)
 n = amount (in units of mole)
 R = gas constant 0.0821 (L*atm) / (mol*K)
 Barometers measure pressure. Barometers may measure in pressure units other than
atmospheres.
 The SI unit for pressure is Pascal.
Ideal Gas
 Ideal gas equation PV = nRT provides a valuable model of the relations between volume,
pressure, temperature and number of particles in a gas.
 To derive gas laws for two sets of conditions, solve the Ideal Gas Law for R

 If the Ideal Gas Law is correct, then above equation would apply under any set of
conditions of P, V, n and T giving,
 Equation 1. Ideal Gas Law for two sets of conditions.

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