Multiple Choice
A sample contains 7.5 g of CaCl2·9H2O. How many grams of pure CaCl2 are present in this sample?
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2. Atoms & Elements
Calculating Molar Mass
Multiple Choice
What is the molar mass of CH3CH2OH (ethanol)? Provide your answer to two decimal places.
A
48.09 g/mol
B
45.06 g/mol
C
46.07 g/mol
D
44.05 g/mol
Verified step by step guidance1
Identify the molecular formula of ethanol, which is CH3CH2OH. This can also be written as C2H6O, meaning it contains 2 carbon (C) atoms, 6 hydrogen (H) atoms, and 1 oxygen (O) atom.
Find the atomic masses of each element from the periodic table: Carbon (C) ≈ 12.01 g/mol, Hydrogen (H) ≈ 1.008 g/mol, Oxygen (O) ≈ 16.00 g/mol.
Calculate the total mass contributed by each element by multiplying the number of atoms by their atomic masses: For carbon, multiply 2 by 12.01; for hydrogen, multiply 6 by 1.008; for oxygen, multiply 1 by 16.00.
Add all these contributions together to get the molar mass of ethanol: \(\text{Molar mass} = (2 \times 12.01) + (6 \times 1.008) + (1 \times 16.00)\).
Sum the values from the previous step to find the total molar mass, and then round your answer to two decimal places as requested.
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