Determine the identity of a 2.97 mole sample of an unknown substance if the sample occupies a volume of 41.6 cm3 and has a density of 6.51 g/cm3.

Question

Element
Hafnium	Molar Mass of 178.49
Vanadium	Molar Mass of 50.9415
Berkelium	Molar Mass of 247.07
Zirconium	Molar Mass of 91.224
Cobalt	Molar Mass of 58.9332

a.Berkelium

b.Hafnium

c.Zirconium (Correct answer)

d.Vanadium

e.Cobalt

Answer 1

Find the molar (atomic) mass of the unknown, and then compare that to knowns in the table

molar (atomic) mass = g / mole

we know we have 2.97 mols, so we need to find g (grams)

41.6 cm³ x 6.51 g / 1 cm³ = 270.8 g

now we can find molar(atomic) mass (g / mol)

270.8 g / 2.97 mol = 91.2 g / mol

It looks like the unknown should be Zirconium