Tuesday, November 30, 2010

Nov 29 2010 - percent composition

Today we went over percent composition.

Percent composition of a compound shows that how much of each elements in the compound and which elements are in the compound.

Percentage compound = mass of element / mass of compound x 100 %

Ex 1. What is the percentage composition of CuCl2?

Total MM(Molar Mass) = 134.5g/mol


% of Cu = 63.5/134.5 x 100 % = 47.2 %

% of Cl = 71.0/134.5 x 100% = 52.8 %


2. What is the percentage ocomposition of CaO?

Total MM = 56.1g/mol

% of Ca = 40.1/56.1 x 100% = 71.5 %

% of O = 16.0/56.1 x 100 % = 29.5


3. Calculate percentage composition of the bolded components of Na2SO4.

Total MM = 142.1g/mol
MM of all the SO4 = 96.1g/mol

% of SO4 = 96.1/142.1 x 100 % = 67.6 %

4. Calculate percentage composition of NaCl.

Total MM = 58.5g/mol

% of Na = 23.0/58.5 x 100 % = 39.3 %

% of Cl = 35.5/58.5 x 100% = 60.7 %

5. Calculate the percentage of bolded components of (NH4)3PO4.

Total MM = 149.1
MM of all the NH4 = 54.0

% of NH4 = 54.0 / 149.1 x 100 % = 36.2 %

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