Measuring Density

Question

The density of platinum is 21.45 g/cm3 at 20˚C. Calculate the mass of 75.00 cm3 of platinum at this temperature.

Answer 1

The equation for density is d=m/V

Where d stands for density (usually in g/mL or g/cm³)

m stands for the mass (usually in g)

V is the volume (usually in mL or cm³) (1 mL = 1 cm³)

So at that point it's just plug in the values into the formula and solve for the mass.

21.45 g/cm³ = m / 75.00 cm³

Multiply both sides by 75.00 cm³ to get m by itself

(75.00 cm³)(21.45 g/cm³) = (m / 75.00 cm³)(75.00 cm³)

The left side will then equal 1608.75 g because the cm³ will cancel out.

The right side will then just equal m because the 75.00 cm³ cancel out as well.

Then because of significant figures (4 in this case), the mass of the object would be 1609 g or 1.609·10³ g)

Answer 2

You can simply use dimensional analysis. 75.00 cm3 x 21.45 g/cm3

note how units of cm3 cancel leaving you with grams.

75.00 cm3 x 21.45 g/cm3 = 1609 g