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WHAT WE CALL 12 PIECES OF BOTTLES ?

WHAT WE CALL 2 PIECES OF BOTTLES ?

AS YOU SAID,PAIR AND DOZENS ARE EXAMPLES OF UNITS THAT WE USED IN MEASURING THE AMOUNT OF OBJECTSIN OUR DAILY LIVESDO YOU KNOW THAT,IN A SIMILAR WAY CHEMIST USE THE UNIT MOLE TO MEASURETHE AMOUNT OF SUBSTANCES!!!! THEY USE MOL AS A SYMBOL OF MOLE.

WHAT IS MOLE ACTUALLY?

SINCE CARBON-12 IS THE STANDARD CHOSEN FOR RELATIVE ATOMIC MASS, WE USE THE NUMBER OF ATOMS IN EXACTLY 12g OF CARBON-12 AS A STANDARD IN MEASURING THE AMOUNT OF SUBTANCES..

THUSWE DEFINE THAT >>A MOLE IS AN AMOUNT OF SUBSTANCE THAT CONTAINS AS MANY PARTICLES AS THE NUMBEROF ATOMS IN EXACTLY 12g OF CARBON-12

CAN YOU GUESS HOW MANY ATOMS ARE THERE IN 12gOF CARBON-12?SCIENTISTS HAD DETERMINE ITS VALUE EXPERIMENTALLYAS 6.02 X 1023 !!!!!!!

6.02 X 1023AVOGADRO CONSTANTTHE AVOGADRO CONSTANT ,NAIS DEFINED AS THE NUMBER OF PARTICLESIN ONE MOLE OF A SUBSTANCE

ONE MOLE OF SUBSTANCECONTAINS 6.02 X 1023 PARTICLES

1 MOL OF MOLECULARSUBSTANCE CONTAINS6.02 X 1023 MOLECULES

1 MOL OF IONICSUBSTANCE CONTAINS6.02 X 1023 FORMULAUNITS1 MOL OF ATOMICSUBSTANCE CONTAINS6.02 X 1023 ATOMS ONE MOLE OF ANY SUBSTANCE IS THE AMOUNT OF SUBSTANCE THAT CONTAINS NA NUMBER OF PARTICLES

NUMBER OF MOLESNUMBER OF PARTICLESNA XNA

CAN YOU SOLVE NUMERICAL PROBLEMS USING THAT FORMULA ?LETS SEE SOME EXAMPLE..

CALCULATE THE NUMBER OF PARTICLESIN 0.2 MOLE OF COPPER ATOMS, Cu

SOLUTION:

1 MOLE OF COPPER CONTAINS6x1023 Cu ATOMS.0.2 MOLE-ATOM COPPER CONTAINS(0.2)/(1)x6x1023 Cu ATOMS=1.2x1023 ATOMS

CALCULATE THE NUMBER OF ATOMSIN 1.2 MOLE OF CHLORINE GAS, Cl2

SOLUTION:

1.2 MOLE OF CHLORINE CONTAINS1.2x6x1023 MOLECULES= 7.2x1023 MOLECULES1 CHLORINE MOLECULE (Cl2) HAS 2 ATOMS.THEREFORE THE NUMBER OF ATOMS= 2x7.2x1023= 1.44x1024 ATOMS

CALCULATE THE NUMBER OF MOLESIN 7.5x1021 CHROMIUM ATOMS

SOLUTIONS:

1 MOLE OF CHROMIUMCONTAIN 6x1023 ATOMS

THEREFORE 7.5x1021 CHROMIUM ATOMS=(7.5x1021)/(6x1023)x1 MOLE=0.0125 MOLE-ATOM

THE NUMBER OF ATOMS IN 0.2 MOLE OF NITROGEN GAS ?

INCORRECT:THE NUMBER OF ATOMS = 0.2x6x1023=1.2x1023

CORRECT:NITROGEN (N2) IS A DIATOMIC MOLECULE.0.2 MOLE OF NITROGEN GAS CONTAIN 1.2x1023 MOLECULES.THE NUMBER OF ATOMS PRESENT=2x1.2x1023=2.4x1023COMMON MISTAKE THAT YOU SHOULD NOT DO!!!

NOW LETS SOLVE THE NEXT PROBLEM BASED ON PREVIOUS EXAMPLES IN GROUP