Find the molecular mass of each of the following to one decimal places, ex: H20
ID: 1055980 • Letter: F
Question
Find the molecular mass of each of the following to one decimal places, ex: H20 H = 2(1.0) = 2.0 O = 1(16.0) = 16.0 H2O = 2.0 + 16.0 = 18.0 After finding the molar mass of #1-3, Find the percent composition of each element in each substance. CuSO4 C2H5OH C2H3O Empirical and Molecular formulas A compound is found to be 57.1 % C, 38.1 % S and the rest is H. Find the empirical formula If the molecule, weight of the compound is 168.0g/mol, determine the molecular formula. A compound is 75.46% carbon, 4.43% hydrogen, and 20.10% oxygen by mass. It has a molecular weight of 318 g/mol. What is the molecular formula for this compound? Caffeine has the following percent composition: carbon 49.48%, hydrogen 5.19%, oxygen 16.48% and nitrogen 28.85%. Its molecular weight is 194.19 g/mol. What is its molecular formula? What is the empirical formula?Explanation / Answer
Answer A)
Finding of molar mass and % Composition of each element constitueating it.
Atomic massess are,
Cu (63.55), S (32), O(16.0), H (1.0)
Also,
% composition of an element = (Atomic mass of element / Molar mass of compound) x 100
Usint this,
1) Copper sulfate CuSO4.
Molar mass of CuSO4 = 1 x Atomic mass of Cu + 1 x Atomic mass of S + 4 x Atomic mass of O
= 1 x 63.55 + 1 x 32.0 + 4 x 16.0
= 63.55 + 32.0 + 64.0
= 159.55
% Cu = (63.55 / 159.55) x 100 = 39.83 %
% S = (32 / 159.55) x 100 = 20.06 %
% O = (64 / 159.55) x 100 = 40.11 %
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2) Ethanol C2H5OH or C2H6O
Molar mass of C2H6O = 2 x Atomic mass of C + 6 x Atomic mass of H + 1 x Atomic mass of O
= 2 x 12.0 + 6 x 1.0 + 1 x 16.0
= 24.0 + 6.0 + 16.0
= 46.0
% C = (24/46) x 100 = 52.18 %
% H = (6/46) x 100 = 13.04 %
% O = (16/46) x 100 = 34.78 %
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3) C2H3O (Something missing in this compound)
Molar mass = 2 x 12.0 + 3 x 1.0 + 1 x 16.0
= 24.0 + 3.0 + 16.0
= 43.0
% C = (24.0/43.0) x 100 = 55.81 %
% H = (3/43) x 100 = 6.98 %
% O = (16/43) x 100 = 37.21 %
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