# Can someone help me math? (Density and converting weight to volume.)

**URL:** <https://boards.straightdope.com/t/can-someone-help-me-math-density-and-converting-weight-to-volume/717487>\
**Category:** Factual Questions\
**Created:** [April 12, 2015, 2:40pm UTC](https://boards.straightdope.com/t/can-someone-help-me-math-density-and-converting-weight-to-volume/717487 "2015-04-12T14:40:37Z")\
**Posts on this page:** 1\
**Page:** 2

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**Author:** ![WhyNot](https://avatars.discourse-cdn.com/v4/letter/w/c77e96/32.png) [@WhyNot](https://boards.straightdope.com/u/WhyNot)\
**Post date:** [April 12, 2015, 10:41pm UTC](https://boards.straightdope.com/t/can-someone-help-me-math-density-and-converting-weight-to-volume/717487/21 "2015-04-12T22:41:30Z")

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> [@LSLGuy](#):
>
> As \*\*Hail Ants \*\*mentioned in post #2, are the purities of the two vendors the same?
> 
> e.g. when buying isopropyl it comes in IIRC, 70%, 80%, and 96(?)%. Businesses love to charge the price of expensive ingredients for added water.
> 
> Does this issue apply to the stuff you’re comparing?

Not in this case, but a very good point for the general case of ordering chemistry supplies!

Back when I was making gallons of herbal tinctures every week, we got the bright idea to order 99.999% pure ethanol to make our dilution math easier. (Some mixtures had to be 80% alcohol, others 45%…).

There’s a reason it’s really hard to order 99.999% ethanol.

I think we got drunk off the fumes. And it evaporated as you poured it, making measuring…exciting. And we had to pay extra hazmat fees to handle it.

We went back to Everclear and our calculators.

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