Hey guys. I’m struggling to understand the concept of moles, and was hoping someone could explain it a lot easier than in previous posts. I understand that a mole of something means that there is 6.022 x 10\^23 of that something (similar to the idea of 1 dozen = 12 things), but I don’t quite understand when for example 1 mole of Nitrogen is 14g.
If 1 mole of nitrogen means that there is 6.022 x 10\^23 nitrogen atoms, how does 1 mole of nitrogen equal 14g? Is it saying that 6.022 x 10\^23 nitrogen atoms (1 mole of nitrogen) is equal to 14g, since the mass of a nitrogen atom (single nitrogen atom) would be super small, and so we use moles to convert it into a reasonable mass for easier calculations e.g. 14g?
Hope that wasn’t too confusing :S
Thanks everyone! 🙂
In: Chemistry
>since the mass of a nitrogen atom (single nitrogen atom) would be super small, and so we use moles to convert it into a reasonable mass for easier calculations e.g. 14g?
Kind of the other way around. We use mass as an approximation for 1 mole of a particular element, because counting 6.022 × 10^(23) would be incredibly time consuming and very, *very* expensive.
Think of it like this. Imagine you sell bulk hardware wholesale to hardware retailers. A customer has placed an order for two hundred fifty thousand (250k) M10 hex nuts. They want the nuts delivered in boxes of 1,000.
As the seller, you have to decide how you’ll go about this. Counting out 250 boxes of 1,000 nuts per box would take a ridiculous amount of labor if you had people do it. You could invest in expensive machinery that automatically counts the nuts, but there is a much cheaper way.
You count out 1,000 nuts one time, then you weigh them. Since all the nuts weigh pretty much the same, 1,000 nuts should weigh the same every time.
So you count out 1,000 nuts, weigh them, and you find that the weight is 11.5 kg. Now you can simply package up the nuts at 11.5 kg per box and you know that you’ll be pretty darn close to 250k nuts when you’re done.
When working with moles of atoms, we do the same thing. We know that 6.022 × 10^(23) nitrogen atoms weighs around 14g, so if we need 1 mole of nitrogen, we just weigh out 14g and call it close enough.
But why would we need a mole of something instead of simply saying we need 14g of something? Sometimes working by quantity is easier to understand than working by mass. For example, if you want to make the molecule H2O, you need two hydrogen and one oxygen. You know the *quantity* of each element required, not the mass. You could calculate the mass, but it’s easier to just work with the quantities directly until you’re done with the math, then convert to mass at the end. Just like when someone orders 250k M10 nuts instead of ordering 2,875 kg of M10 nuts. Sometimes we need to work in quantities, not mass. That’s where the mole is handy.
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