Question

How many ethyne molecules are contained in 84.3 grams of ethyne (C2H2)?

Answer 1

(~26grams/mole) and Avogadros # (6.022x10^23) 84.3grams x 1mole/26grams x 6.022x10^23 molecules/mole = 1.95x10^24 molecules of C2H2

Answer 2

Explanation:

According to the mole concept, there are $6.022 \times 10^{23}$ atoms or molecules present in 1 mole.

As, it is given that mass of ethyne is 84.3 g. Hence, calculate its number of moles as follows.

          No. of moles = $\frac{mass}{\text{molar mass}}$

                                 = $\frac{84.3 g}{26.04 g/mol}$

                                 = 3.24 mol

Therefore, calculate number of ethyne molecules as follows.

                 $3.24 mol \times 6.022 \times 10^{23}$ atoms

                    = $19.51 \times 10^{23}$ atoms

Thus, we can conclude that there are $19.51 \times 10^{23}$ atoms in 84.3 grams of ethyne.