"Hun kjøper en mengde forskjellige ting."
Translation:She is buying a lot of different things.
The couple instances I've encountered this word I've seen it paired with the preposition "med", e.g. "Hun kjøper en mengde med ting." Is this normal or am I mistaken?
I wouldn't say that, there's not much of a difference. Here, 'med' might direct the attention even more towards what is being bought, instead of the one purchasing.
'Med' is used in other sentences as well: -"Jeg er med dem" (I'm with them) -"Hun snakker med ham" (She talks with him) -"Hvordan går det med deg?" (How are you doing?)
Some more examples of 'med' (in Norwegian): http://www.nob-ordbok.uio.no/perl/ordbok.cgi?OPP=med&ant_bokmaal=5&ant_nynorsk=5&bokmaal=+&ordbok=begge
As far as I understand both translations, you can use both 'mengde' and 'masse' to express something like 'a lot of'. But 'masse' also translates to 'mass' (e.g. 1kg) and 'menge' refers to 'amount' (e.g. 1 mole, 10 pieces). Therefore it is not always interchangeble, especially in a scientific context!
Instead of 'en mengde' could you write 'mye'?
Hun kjøper mye forskjellige ting.