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PERCENT COMPOSITION

PERCENT COMPOSITION. mass of element. % mass of element. =. X 100. mass of compound. The relative amounts of the elements in a compound are expressed as the percent composition.

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PERCENT COMPOSITION

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  1. PERCENT COMPOSITION mass of element % mass of element = X 100 mass of compound

  2. The relative amounts of the elementsin a compound are expressed as the percent composition. The percent by mass of an element in a compound is the number of grams of the element divided by the mass in grams of the compound, multiplied by 100.

  3. PERCENT COMPOSITION FROM A FORMULA Propane(C3H8), is the fuel commonly used ingas grills. Calculate the percent composition of propane. KNOWNS REMEMBER: part whole • Mass of C in propane • Mass ofHin propane • Molar mass of propane C: 12.0(3) = 36.0g/mol X 100 H: 1.0(8) = 8.0g/mol 44.0g/mol CALCULATE 36.0 g % C = C__ = 81.8% X 100 = X 100 propane 44.0 g 8.0 g = 18.2% % H = H___ X 100 X 100 = propane 44.0 g

  4. PERCENT COMPOSITION FROM A FORMULA Try this with your partner. . . Find the percent composition of water. REMEMBER: part whole KNOWN X 100 • Formula of water • Mass of hydrogen in water • Mass of oxygen in water H2O H: 1.0(2) = 2.0g/mol O: 16.0(1) = 16.0g/mol CALCULATE 2.0 18.0 X 100 = 11.1 % % H = 88.9 % X 100 = % O = 16.0 18.0

  5. PERCENT COMPOSITION FROM MASS DATA When a 13.60 g sample of a compound containing only Mg & O is decomposed. 5.40 g of O is obtained. What is the % comp. of this cmp? REMEMBER: If you are not given each of the elements SUBTRACT to find them! KNOWN • Mass of compound = 13.60 g • Mass of oxygen = 5.40 g • Mass of magnesium when you subtract • 13.60g – 5.40 g = 8.20 g Mg REMEMBER: part whole CALCULATE X 100 8.20 13.60 X 100 % Mg = 60.3 % = 5.40 13.60 X 100 = 39.7 % = % O

  6. PERCENT COMPOSITION FROM MASS DATA Try this with your partner. . . A 34.0 g sample of a compound containing 8.5 g of O is formed. The remaining portion is composed of Ca. What is the % composition of this compound? REMEMBER: If you are not given each of the elements SUBTRACT to find them! KNOWN Mass of compound = 34.0 g Mass of oxygen = 8.5 g Mass of calcium when you subtract 34.0g – 8.5 g = 25.5 g Ca CALCULATE REMEMBER: part whole X 100 25% oxygen 75.0% calcium

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