# A piece of platinum metal with a density of 21.5 g/cm^3 has a volume of 4.49 cm^3. What is its mass?

Jun 6, 2017

$96.5 g$

#### Explanation:

Use the formula for density but rearrange the formula to solve for mass:

$d = \frac{m}{v}$ where $d$ is the density in $\frac{g}{c {m}^{3}}$, $m$ is the mass in $g$, and $v$ is the volume in $c {m}^{3}$:

Given the information we can write a formula like so:

$21.5 = \frac{m}{4.49}$

We are trying to find the mass so we can rewrite the equation such that we solve for $m$:

$4.49 \cdot 21.5 = \frac{m}{\cancel{4.49}} \cancel{4.49}$

$4.49 \cdot 21.5 = m$

$96.533 = m$

$96.5 g = m$ (With proper sigfigs)

We could check this answer by substituting our newly found mass and given volume to find density. In doing this, we should get $21.5 \frac{g}{c {m}^{3}}$ because that's what the problem told us;

Check:
$d = \frac{96.5}{4.49}$

$d = 21.5$