Question

Analysis of an athletes urine found the presence of a compound with a molar mass of 312 g/mol. How many moles of this compound are contained in 30.0 mg? How many molecules of the compound is this?

Answer 1

= 5.79 × 10^19 molecules

Step-by-step explanation:

The molar mass of the compound is 312 g/mol

Mass of the compound is 30.0 mg equivalent to 0.030 g (1 g = 1000 mg)

We are required to calculate the number of molecules present

We will use the following steps;

Step 1: Calculate the number of moles of the compound

`Moles=(mass)/(molar mass)`

Therefore;

Moles of the compound will be;

`=(0.030)/(312g/mol)`

= 9.615 × 10⁻5 mole

Step 2: Calculate the number of molecules present

Using the Avogadro's constant, 6.022 × 10^23

1 mole of a compound contains 6.022 × 10^23 molecules

Therefore;

9.615 × 10⁻5 moles of the compound will have ;

= 9.615 × 10⁻5 moles × 6.022 × 10^23 molecules

= 5.79 × 10^19 molecules

Therefore the compound contains 5.79 × 10^19 molecules