Question

The mass spectrograph of copper shows two isotopes. One with mass 62.9296 g/mole that has a percentage of 69.200 % and one that is 30.800 % with mass 64.9278g/mole.

Find the molar mass of a sample of naturally occurring copper.

Answer 1

Molar mass = 63.54 approximately

Step-by-step explanation:

In order to find the molar mass of a sample of naturally occurring copper, we can use the weighted average of the molar masses of its isotopes, taking into account their relative abundances. The formula for calculating the weighted average molar mass is:

`\sf \textsf{Average Molar Mass} = (\textsf{Abundance}_1 * \textsf{Mass}_1) + (\textsf{Abundance}_2 * \textsf{Mass}_2)`

Given the information provided:

Isotope 1:

• Mass: 62.9296 g/mol
• Abundance: 69.200% = 0.692

Isotope 2:

• Mass: 64.9278 g/mol
• Abundance: 30.800% = 0.308

Let's plug in the values and calculate:

`\sf \textsf{Average Molar Mass} = (0.692 * 62.9296) + (0.308 * 64.9278)`

`\sf \sf \textsf{Average Molar Mass} = 43.5460376+ 19.9977624`

`\sf \textsf{Average Molar Mass} = 63.5438`

So, the molar mass of a sample of naturally occurring copper is approximately. 63.54.