chem 151 mass and density

Question

Calculate these masses.

(a)

What is the mass (in g) of 5.75 cm³ of palladium, density = 12.00 g/cm³?

(b)

What is the mass (in g) of 30.0 mL cyclohexane, density = 0.779 g/cm³?

Answer 1

Density = mass/volume

D = m/V

so m = D*V

for a) m = 12*5.75 = 69.0 g

for b) 1 mL = 1 cm³ so 30.0 mL = 30 cm³. Using that, m = 30*0.779 = 23.4 g

Answer 2

Answer 3

This problem requires the use of manipulating the variables within the density equation: Density(D) = mass(m)/volume(). In part a, we will be substituting the values for density and volume. When we isolate m, we find:

m = D*V = 12 cm³ x 5.75 g/cm³ = 69.0 g. Notice how the units cancel out to leave the units needed

For part b, we need to use the conversion factor 1 ml = 1cm³ and then the problem becomes substituting in values and solving for the mass.

30.0 mL = 30 cm³.

D = m/v Rearranging we get:

m = v * D = 30 cm³. *0.779 g/cm³ = 23.4 g