# Question #8dd63

##### 1 Answer
Feb 23, 2015

You would need $380 \mu \text{L}$ of absolute ethanol to prepare that particular solution.

So, your $\text{1.2-mL}$ sample must contain clarified yeat extract and ethanol.

${V}_{\text{solution") = V_("yeast") + V_("ethanol}}$

Since the only source of ethanol for your solution will be the absolute ethanol, all you need to do is determine how much ethanol your sample contains.

A $\text{32% v/v}$ solution implies that you have $\text{32 mL}$ of ethanol for every $\text{100 mL}$ of solution. This means that your sample will contain

$\text{1.2 mL solution" * ("32 mL ethanol")/("100 mL solution") = "0.384 mL ethanol}$

Rounded to two sig figs, the answer will be $\text{0.38 mL}$.

In microliters, this is equal to

$\text{0.38 mL" * (1000mu"L")/("1 mL") = "380"mu"L}$

As a conclusion, if you mix $\text{0.38 mL}$ absolute ethanol with $\text{0.82 mL}$ clarified yeast extract you'll end up with $\text{1.2 mL}$ of a $\text{32%}$ ethanol solution.