Final answer:
To find the number of atoms in 3.0 moles of copper, multiply the moles by Avogadro's number. The calculation gives us 1.8 x 10²¶ atoms of copper when rounded to two significant figures.
Step-by-step explanation:
To calculate the number of atoms in 3.0 moles of copper, we simply multiply the number of moles by Avogadro's number, which is the number of atoms in one mole of any substance. Avogadro's number is approximately 6.02 x 10²³ atoms/mol.
So the calculation would be:
3.0 moles of Cu x (6.02 x 10²³ atoms/mol of Cu) = 18.06 x 10²³ atoms of Cu
However, we must express this number in proper scientific notation. To do this, we shift the decimal point three places to the left to get 1.806. The exponent on the 10 increases by three to compensate for each place we moved the decimal point:
1.806 x 10²¶ atoms of Cu
When rounding to two significant figures, we obtain 1.8 x 10²¶ atoms of Cu.