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The greatest pleasure in life is doing what people say you cannot do.

The greatest pleasure in life is doing what people say you cannot do. NOW, WE WOULD LIKE TO BE ABLE TO CALCULATE HOW MANY ATOMS OF EACH TYPE ARE INVOLVED IN DIFFERENT SUBSTANCES. WE CAN FIGURE OUT HOW MANY GRAMS OF EACH SUBSTANCE ARE INVOLVED IN DIFFERENT COMPOUNDS.

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The greatest pleasure in life is doing what people say you cannot do.

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  1. The greatest pleasure in life is doing what people say you cannot do.

  2. NOW, WE WOULD LIKE TO BE ABLE TO CALCULATE HOW MANY ATOMS OF EACH TYPE ARE INVOLVED IN DIFFERENT SUBSTANCES. WE CAN FIGURE OUT HOW MANY GRAMS OF EACH SUBSTANCE ARE INVOLVED IN DIFFERENT COMPOUNDS. BUT, WE CAN’T WEIGH INDIVIDUAL ATOMS. 1 ATOMIC MASS UNIT = 1.67 X 10-24 grams ROUTINE MASS DETERMINATIONS ARE VERY DIFFICULT MUCH BELOW 10-6 grams.

  3. WHAT WE CAN DO IS TO WORK WITH LARGER QUANTITIES OF MATTER THAT CONTAIN EQUAL NUMBERS OF ATOMS. IF YOU LOOK AT THE ATOMIC MASSES GIVEN ON THE PERIODIC TABLE, IT TURNS OUT THAT IF YOU TAKE THESE MASSES IN GRAMS, THEY WILL CONTAIN THE SAME NUMBER OF ATOMS. THIS NUMBER IS REFERRED TO AS AVOGADRO’S NUMBER OR ONE MOLE. 6.023 X 1023 = 1 mole

  4. MOLAR MASS– THE MASS OF ONE MOLE OF ITS CHEMICAL FORMULA UNIT. THE MOLAR MASS CAN BE FOUND BY ADDING THE MOLAR MASSES OF ALL ELEMENTS PRESENT WITHIN THE COMOUND. EXAMPLE: MOLAR MASS OF H2SO4 2 H = 2 X 1 = 2 1 S = 1 X 32 = 32 4 O = 4 X 16 = 64 Molar mass = 98 g/mole

  5. CALCULATE THE MOLAR MASSES OF THE FOLLOWING: K3PO4 TiBr2 Fe2S3 CH3CH2OH IN THE CASE OF IONIC COMPOUNDS,WE SOMETIMES USE THE TERM FORMULA UNIT MASS RATHER THAN MOLAR MASS,AS TRUE MOLECULES DO NOT EXIST IN IONIC COMPOUNDS.

  6. ANOTHER LOOK AT FORMULAS AND MOLES. MOLECULAR FORMULA – A COLLECTION OF SYMBOLS REPRESENTING THE NUMBER OF ATOMS OF EACH ELEMENT IN A MOLECULE OF A COMPOUND. EMPIRICAL FORMULA – THE SIMPLEST WHOLE NUMBER RATIO OF THE ATOMS IN A MOLEUCLE OF A COMPOUND. IF WE ARE TALKING ABOUT AN IONIC COMPOUND, THE FORMULA UNIT, OR FORMULA, IS THE SAME AS THE EMPIRICAL FORMULA.

  7. FOR EXAMPLE, THE MOLECULAR FORMULA FOR A SIMPLE SUGAR IS: C6H12O6 THE EMPIRICAL FORMULA IS: CH2O IF YOU KNEW THE EMPIRICAL FORMULA, AND YOU KNEW THE MOLAR MASS WAS 180, YOU COULD CALCULATE THE MOLECULAR FORMULA.

  8. THE EMPIRICAL FORMULA MASS WOULD BE: 1 C = 1 X 12 = 12 2 H = 2 X 1 = 2 1 O = 1 X 16 = 16 EMPIRICAL FORMULA MASS = 12 + 2 + 16 = 30 MOLAR MASS/EFM = 180/30 = 6 SO THE MOLAR MASS IS 6 TIMES THE EMPIRICAL FORMULA MASS, SO THE MOLECULAR FORMULA IS: 6 X CH2O = C6H12O6

  9. MOLE/FORMULA PROBLEMS: HOW MANY GRAMS OF MgCl2 ARE IN 1.5 MOLES? HOW MANY MOLES OF Cl- ARE IN 0.255 g OF MgCl2 ? HOW MANY ATOMS OF OXYGEN ARE IN 75.0 g OF Fe2O3? HOW MANY ATOMS OF C ARE IN 1.05 g TOLUENE?

  10. MASS PERCENT COMPOSITION – THE RELATIVE MASS OF EACH ELEMENT PRESENT IN A GIVEN COMPOUND. PLEASE REMEMBER: EVERY CHEMICAL COMPOUND HAS A DEFINITE CHEMICAL FORMULA, WHICH INDICATES THAT EVERY CHEMICAL COMPOUND HAS A DEFINITE PERCENT MASS COMPOSITION. EXAMPLE: CALCULATE THE % C IN ACETALDEHYDE, C2H4O.

  11. IF YOU KNOW THE % COMPOSITION, YOU CAN CALCULATE THE EMPIRICAL FORMULA. SOLID TARTARIC ACID, WHICH IS PRODUCED IN THE FERMENTATION OF WINE, HAS THE PERCENT COMPOSITION 32.01% C, 4.03% H, AND 63.96% O . CALCULATE THE EMPIRICAL FORMULA.

  12. Find an empirical formula for a substance with 53.28% C, 15.65% H, and 31.07% N. Find the empirical formula for a compound with 11.33% C, 45.29% O, and 43.38% Na.

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