mass reactants = mass products
Post on 05-Jan-2016
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Mass Reactants = Mass Products
Law of Conservation of Mass: the mass of the reactants must equal the mass of the
products.
Law of Definite Proportions: a compound (like H2O) is always composed of the same elements in the same proportion by mass (no matter what the sample size).
% by Mass = mass of element (g) x 100 mass of compound (g)
Example: 78.0g of Unknown Compound 12.4g of Hydrogen (H) ? = % by mass of H
% by Mass H = mass of hydrogen (g) x 100 mass of unk compound (g)
= 12.4 g H x 10078.0g Unk Compound
= 15.9%
Practice:A 24.0g sample of unknown compound contains 6.5 g of hydrogen. What is the percent by mass of hydrogen in the compound?
Start by writing down your information.
Practice:A 24.0g sample of unknown compound contains 6.5 g of hydrogen. What is the percent by mass of hydrogen in the compound?
24.0 g of Unknown Compound 6.5 g of Hydrogen (H) ? = % by mass of H
Now, set up the equation & plug in the numbers.
Practice:A 24.0g sample of unknown compound contains 6.5 g of hydrogen. What is the percent by mass of hydrogen in the compound?
24.0 g of Unknown Compound 6.5 g of Hydrogen (H) ? = % by mass of H
% by Mass H = mass of hydrogen (g) x 100 mass of unk compound (g)
Practice:A 24.0g sample of unknown compound contains 6.5 g of hydrogen. What is the percent by mass of hydrogen in the compound?
24.0 g of Unknown Compound 6.5 g of Hydrogen (H) ? = % by mass of H
% by Mass H = 6.5 g Hydrogen x 100 24.0 g Unk Compound
Practice:A 24.0g sample of unknown compound contains 6.5 g of hydrogen. What is the percent by mass of hydrogen in the compound?
24.0 g of Unknown Compound 6.5 g of Hydrogen (H) ? = % by mass of H
% by Mass H = 6.5 g Hydrogen x 100 24.0 g Unk Compound= 27.1% by mass of Hydrogen
Law of Multiple Proportions: when different compounds are formed by a combination of the same elements, different masses of one element combine with the same relative mass of the element in a ratio of small whole numbers (can use colons or fractions).
Law of Multiple Proportions
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