Question

An aluminum atom has a mass of 4.48 * 10-23 g and a small airplane has a mass of 5000 kg. Use this information to answer the questions below. Be sure your answers have the correct number of significant digits.
(a) What is the mass of 1 mole of aluminum atoms?
(b) How many moles of aluminum atoms have a mass equal to the mass of a small airplane?

Answer 1

You should know that 1 mole has 6.02 x 10*23 atoms (Avogadro)...so if you have one atom with 4.48 *10-23 g...then 6.02 *10*23 how many??.. try the rule of 3...answer A is 26,9696 g. For answer b, first of all covert the 5000 kg to 5000000 g (you can write 5 x 10*6)..afterwards make the rule of 3.. if 26,9696 g they are in 1 mole, the mass of the plane 5 x 10*6 g... how many moles?.. be careful with g and the kg.!!.. Answer B should be 185393, 92 moles.

Answer 2

Explanation:

(a)   According to the mole concept, 1 mole of an atom contains $6.022 \times 10^{23}$ atoms.

Hence, number of atoms present in $4.48 \times 10^{-23}$ g will be as follows.

                 $4.48 \times 10^{-23} \times 6.022 \times 10^{23}$

                 = 26.97 g

or,              = 27 g

This means that 1 mole of aluminium atoms contain 27 g.

(b)     Mass of air plane is 5000 kg of $5000 \times 1000 g$ (as 1 kg = 1000 g).

As mass of 1 mole aluminium is calculated as 27 g and mass of air plane is given as 5000000 g.

Therefore, calculate the number of moles of aluminium atoms as follws.

               No. of moles of Al atoms = $\frac{\text{mass of small air plane}}{\text{mass of 1 mol Aluminium}}$

                                             = $\frac{5000000g}{27 g}$

                                              = 185185.18

So, the answer in three significant digits will be 185000 moles of aluminum atoms have a mass equal to the mass of a small airplane.