what is the mass of 3x1024 particles of ethylene?

Answer 1

Here we will want the molar mass of ethylene which is 28.05 g/mol.

We know there are 6.022*10^23 particles in a mole. So we can convert the 3*10^24 particles of ethylene to moles. So we take 3*10^24 particles * 1mole / 6.022*10^23 particles = 4.98 mol of ethylene

Then we can convert the moles to mass = 4.98 mol * 28.05 g/mol = 139.74 grams

But we will want only 1 significant figure here so we will round this to 1*10^2 grams of ethylene

Answer 2

Ethylene = C2H4

molar mass = 12x2 + 4x1 = 24 + 4 = 28 g/mol

Use Avogadro's number to find moles of C₂H₄ in 3x10²⁴ particles (molecules) of C₂H₄

3x10²⁴ particles C₂H₄ x 1 mol C₂H₄/6.02x10²³ particles = 4.98 moles C₂H₄ = 5 moles C₂H₄

5 moles C₂H₄ x 28 g/mol = 139 g C₂H₄ = 140 g C₂H₄ (2 sig. figs.) = mass C₂H₄ (100 g rounded to 1 s.f.)