# How many molecules of glucose are in a xenopus oocyte if the total volume is 10 ul and the concentration of glucose is 10 mM?

Sep 21, 2016

There are 6.0 × 10^15color(white)(l) "molecules" of glucose in the oocyte.

#### Explanation:

The formula for molarity is:

color(blue)(bar(ul(|color(white)(a/a) "Molarity" = "moles"/"litres"color(white)(a/a)|)))" "

or

$\textcolor{b l u e}{\overline{\underline{| \textcolor{w h i t e}{\frac{a}{a}} M = \frac{n}{V} \textcolor{w h i t e}{\frac{a}{a}} |}}} \text{ }$

$M = \text{10 mmol/L" = 1.0 × 10^"-3"color(white)(l) "mol·L"^"-1}$
$V = \text{10 µL" = 1.0 × 10^"-5"color(white)(l) "L}$
n = MV = (1.0 × 10^"-3"color(white)(l) "mol")/(1 color(red)(cancel(color(black)("L")))) × 1.0 ×10^"-5" color(red)(cancel(color(black)("L"))) = 1.0 × 10^"-8"color(white)(l) "mol"
$\text{Molecules" = 1.0 × 10^"-8" color(red)(cancel(color(black)("mol"))) × (6.022 × 10^23color(white)(l) "molecules")/(1 color(red)(cancel(color(black)("mol")))) = 6.0 × 10^15color(white)(l) "molecules}$