Question

Find the number of millimoles of KOH in a sample containing 30 KOH formula units.

• A. $4.98\times {10}^{-23}$
• B. $0.498\times {10}^{-23}$
• C. $4.98\times {10}^{23}$
• D. $4.98\times {10}^{-20}$

Answer 1

The correct option is D $4.98\times {10}^{-20}$

We know,
$6.022\times {10}^{23}$ formula units of KOH = 1 mole of KOH

So, 30 formula units of KOH = $\frac{30}{6.022\times {10}^{23}}$ moles of KOH
$=\left(\frac{30}{6.022\times {10}^{23}}\right)\times {10}^3$ millimoles of KOH $=4.98\times {10}^{-20}$ millimoles of KOH