Hexane is a hydrocarbon (a molecule containing only carbon and hydrogen) with a molecular weight of 86.18 g/mol,
a density of 0.660 g/mL, and a boiling point of 69C .
Pentanol is an alcohol (a hydrocarbon with a "OH" group attached to one of its carbons) with a molecular weight of
88.15 g/mol, a density of 0.814 g/mL, and a boiling point of 137C .
Calculate the volumes if 4.50 moles of each chemical is present.
Hexane: mL
Pentanol: mL
Think about this for the experiment you will perform in lab this week: You calculated the above volumes from the same number of molecules (moles). Why did you end up with two different volumes? The answer goes beyond the differences in the formula weights and densities.
What is your thinking? I will be happy to critique your thinking. Please refrain from posting under multiple names
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To calculate the volumes of 4.50 moles of hexane and pentanol, we need to use the equation:
Volume = (moles * Molecular weight) / Density
1. For hexane:
Molecular weight = 86.18 g/mol
Density = 0.660 g/mL
Volume = (4.50 mol * 86.18 g/mol) / 0.660 g/mL
Volume = 586.41 mL
So, the volume of 4.50 moles of hexane is 586.41 mL.
2. For pentanol:
Molecular weight = 88.15 g/mol
Density = 0.814 g/mL
Volume = (4.50 mol * 88.15 g/mol) / 0.814 g/mL
Volume = 487.09 mL
So, the volume of 4.50 moles of pentanol is 487.09 mL.
Now, let's consider why the volumes are different for the same number of moles. The key factors that influence the volume are molecular weight and density. Hexane has a lower molecular weight than pentanol, which means that a given mass of hexane contains more molecules than the same mass of pentanol. Consequently, the volume needed to hold the same number of moles for hexane is greater than for pentanol.
Furthermore, the densities of hexane and pentanol are different. Hexane has a density of 0.660 g/mL, while pentanol has a density of 0.814 g/mL. Density is a measure of how closely packed the molecules are in a substance. So, even if two substances have the same molecular weight, their densities can vary, leading to different volumes required to hold the same number of moles.
In summary, the difference in molecular weights and densities of hexane and pentanol leads to different volumes required for the same number of molecules (moles).