Question

how many moles are in 78.9 grams of fes? include the unit with the answer, but do not write the chemical formula.
answer:

Explanation:

Step1: Calculate molar mass of FeS

Molar mass of Fe: $55.85\ g/mol$, molar mass of S: $32.07\ g/mol$.
Molar mass of FeS = $55.85 + 32.07 = 87.92\ g/mol$.

Step2: Use moles formula ($n = \frac{m}{M}$)

Given mass $m = 78.9\ g$, molar mass $M = 87.92\ g/mol$.
$n = \frac{78.9}{87.92} \approx 0.897\ mol$.

Answer:

$0.90\ mol$ (or $0.897\ mol$, depending on precision)