Answer:
3.46 x 10²³ atoms C₃H₈
Step-by-step explanation:
To find the total atoms, you need to (1) convert grams to moles (via molar mass from periodic table) and then (2) convert moles to atoms (via Avogadro's number). It is important to arrange the ratios/conversions in a way that allows for the cancellation of units. To clarify, the desired unit should be in the numerator. The final answer should have 3 sig figs to match the given value (25.3 g).
Molar Mass (C₃H₈): 3(12.01 g/mol) + 8(1.008 g/mol)
Molar Mass (C₃H₈): 44.094 g/mol
Avogadro's Number:
6.022 x 10²³ atoms = 1 mole
25.3 g C₃H₈ 1 mole 6.022 x 10²³ atoms
-------------------- x ------------------ x -------------------------------- =
44.094 g 1 mole
= 3.46 x 10²³ atoms C₃H₈