# Question #b94a2

Jul 18, 2017

Well what is $0.61 \cdot m o l \times 58.44 \cdot g \cdot m o {l}^{-} 1$?

#### Explanation:

Approx. $36 \cdot g$? The key part of the answer is NOT the numerical figure but the dimensional analysis.

The product of the dimensions, $\cancel{m o l} \times g \cdot \cancel{m o {l}^{-} 1} = g$, which we require for a mass......and sometimes this sort of dimensional analysis allows you to check your answer, and determine whether you should divide or multiply.

And remember what a mole represents. It is simply a large number, $6.022 \times {10}^{23} \cdot m o {l}^{-} 1$.....

And here we have $6.022 \times {10}^{23} \cdot m o {l}^{-} 1 \times 0.61 \cdot m o l \times 2$ $\text{sodium}$ and $\text{chloride}$ ions..... Now this is dimensionally consistent as before. Is it? Why did I include the $2$ factor in the product? Did I make a mistake?