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EXPLAIN MOLE CONCEPT,AVOGADRO'S LAW,GAYLUSSAC'S LAW WITH 20 PROBLEMS ON EACH LAW

Mole concept:
A mole is equivalent to 6.022 x 1023 (Avogadro's constant) units.It is a convenient unit for counting. The periodic table provides molar masses, i.e. the number of grams of an element equivalent to one mole of atoms of that specific element. This can be extrapolated to molecules of known molecular formula.
Prblm: Calculate the number of moles of Ag contains 1.204 * 1024 atoms?
Particles to Moles
 number of Particles * (1 mole/6.02 x 1023)= number of moles
                                                                     = 1.204 x 1024 atoms Ag * (1 mol/6.02 x 1023 atoms Ag)= 2 moles of Ag

Avogadro’s law:

Equal volumes of gases, at the same pressure and temperature, contain equal amounts of molecules. The law can be used to find the volumes of gases in a reaction:

Prblm:What volume of oxygen is needed to completely burn 1g of methane? (C = 12 H = 1 , 1 mole of gas occupies 24dm3)?
             CH4 + 2O2 -----> CO2 + 2H20
             1mol   2mol
Molecular mass of methane is 12 + 1 + 1 + 1 + 1 = 16 g/mole

1g is 1/16 of a mole or 0.0625 moles

From the equation you can see that 1 mole of methane burns in 2 moles of oxygen gas. Therefore, 0.0625 moles of methane burns in 2 x 0.0625 moles of oxygen, or 0.13 moles.

We know that 1 mole of gas occupies 24 dm3,
0.13 moles occupies 24 x 0.13 dm3 = 3.12 dm3

Gay Lussac's Law:

Gay-Lussac's Law states that the pressure of a sample of gas at constant volume, is directly proportional to its temperature in Kelvin.

According to Gay-Lussac's Law: P1 / T1 = constant
After the change in pressure and temperature,
  P2 / T2 = constant
Combine the two equations:
                                  P1 / T1 = P2 / T2

Prblm: 10.0 L of a gas is found to exert 97.0 kPa at 25.0°C. What would be the required temperature (in Celsius) to change the pressure to standard pressure?

Solution: Let x be the required temperature.Change 25.0°C to 298.0 K and remember that standard pressure in kPa is 101.325. Insert values into the equation and get:
                  97.0kPa/298.0K = 101.325kPa/x

The answer is 311.3 K, but the question asks for Celsius, so you subtract 273 to get the final answer of 38.3°C.The volume (as well as the moles) remains constant.





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