# Show how one would set up a ration to determine the mass of a substance given that the density was 5.6g/ml with a volume of 3.7ml. What is the mass?

Oct 19, 2016

rho("density")="mass"/"volume"

#### Explanation:

And thus mass is simply the product:

$\text{mass}$ $=$ $\text{volume "xx" density}$.

For your problem, $\text{mass}$ $=$ $5.6 \cdot g \cdot \cancel{m {L}^{-} 1} \times 3.7 \cdot \cancel{m L}$ $=$ ??g

Note that using the units in the calculation automatically gives the correct units, $\text{grams}$, for the answer. This is called dimensional analysis, and you can use it as a check on your calculations. It is also too easy to divide when you should have mulitplied, or multiplied when you should divide. Solving a problem dimensionally helps to avoid this.