Lab 6.2 questions

[Rachel Herold]

My first question is to do with the store bought 70% ethyl alcohol I bought.

Using Table 6-2 on pg 99, I filled in A as 42.1 g and B as 127.4.
This gave me a mass of 85.3g for C.
Which gave me a density of .853g/mL for D.

I then looked up the concentration via this table, http://www.handymath.com/cgi-bin/ethanolwater3.cgi?submit=Entry

Looking up .853 gave me a concentration of 76%. Which contradicts the bottles label of 70%.

Am I doing something wrong?

[The Home Scientist]

Hi, Rachel

You didn't do anything wrong. 0.85 g/mL is a good value for 70% ethanol.