Question

the skeletal structure of (2e)-but-2-enamide (mm = 85.106 g/mol) is shown below: how many carbon atoms are present in 27.1 g of (2e)-but-2-enamide? report your answer using scientific notation to one decimal place.

Explanation:

Step1: Calculate the number of moles

Use the formula $n=\frac{m}{M}$, where $m = 27.1\ g$ and $M=85.106\ g/mol$.
$n=\frac{27.1}{85.106}\ mol\approx0.3184\ mol$

Step2: Determine the number of molecules

Use Avogadro's number $N_A = 6.022\times 10^{23}\ molecules/mol$. The number of molecules of (2E)-but - 2 - enamide, $N=n\times N_A$.
$N = 0.3184\times6.022\times 10^{23}\ molecules\approx1.9174\times 10^{23}\ molecules$

Step3: Count carbon atoms per molecule

From the structure, there are 4 carbon atoms per molecule of (2E)-but - 2 - enamide.

Step4: Calculate the number of carbon atoms

Multiply the number of molecules by the number of carbon atoms per molecule.
$N_{C}=4\times N=4\times1.9174\times 10^{23}=7.6696\times 10^{23}\approx7.7\times 10^{23}$

Answer:

$7.7\times 10^{23}$