Question

How many molecules of methane, CH4 are in 125 g CH4

Answer 1

4.69 x 10²⁴ molecules CH₄

Step-by-step explanation:

To find the amount of molecules, you need to (1) convert grams to moles (via molar mass) and then (2) convert moles to molecules (via Avogadro's Number). It is important to arrange the conversions in a way that allows for the cancellation of units. The final answer should have 3 sig figs to match the sig figs of the given value (125 g).

Molar Mass (CH₄): 16.05 g/mol

Avogadro's Number:

6.022 x 10²³ molecules = 1 mole

125 g CH₄ 1 mole 6.022 x 10²³ molecules
---------------- x --------------- x ------------------------------------- =
16.05 g 1 mole

= 4.69 x 10²⁴ molecules CH₄