Question

The density of platinum is `21.5` `g``/``cm^3` at 25°C. What is the volume of 79.5 g of platinum at this temperature?

Answer 1

The `Volume` of platninum @ `25^oC` is `3.70cm^3`

Explanation:

`Given Data:`

`Density = 21.5 g/(cm^3)`
`Mass= 79.5 g`

`Required:` `Volume = ?`

`Solution:`

From the formula
`Density = (Mass)/(Volume)`; rearrange to find the volume
`Volume=(Mass)/(Density)`; plug in the given data
`Volume=(79.5cancelg)/(21.5cancelg/(cm^3)`
`Volume=3.70cm^3`

`Answer:` `3.70cm^3`

Answer 2

Approx. `4` `cm^3`.

Explanation:

Density, `rho`, is simply mass per unit volume, and has units `g*cm^-3`. So if mass is divided by density, we should get an answer in `1/(cm^-3)`, i.e. in `cm^3`.

So, `rho` `=` `"Mass"/"Volume"`; likewise, `Volume` `=` `"Mass"/rho`:

`"Volume"` `=` `(79.5*cancelg)/(21.5*cancelg*cm^-3)` `=` `??` `cm^3`.