Question

Determine the mass in grams of 7.75 × 10²¹ atoms of carbon. (The mass of one mole of carbon is 12.01 g.)

Answer 1

Answer: Hope this Help :)

Explanation:

First Step: Mass Moles

- To calculate the moles of Au, multiply the given mass by the reciprocal of the molar mass.

58.27g Au×1mol Au196.967g Au= 0.295836 mol Au

I'm keeping a couple of guard digits to reduce rounding errors. The final answer will be rounded to four significant figures.

Second Step: Moles Atoms

- To calculate atoms of Au, multiply moles Au by Avogadro's number.

0.295836mol Au×6.022×1023atoms Au1mol Au=1.782×1023atoms Au

rounded to four significant figures due to 58.72 g

- So, if you are given the mass of an element, you use the periodic table to find its molar mass, and multiply the given mass by the reciprocal of the molar mass. This is Mass Moles

- Once you have moles, multiply by Avogadro's number to calculate the number of atoms. This is Moles  Atoms

How many atoms of zinc, Zn, are in 120.71 g Zn?

Answer: 1.112×1024 atoms Zn

Answer 2

The mass in grams of $7.75$ × $10^{21}$ atoms of carbon is $0.154$ g.

Explanation:

Mass of one mole of carbon $= 12.01$ g

And, $1$ mole $= 6.022$ × $10^{23}$ atoms

Therefore,

Mass of $6.022$ × $10^{23}$ atoms of carbon $= 12.01$ g

Mass of $1$ atom of carbon $= \frac{12.01}{6.022*10^{23} }$ g

Mass of $7.75$ × $10^{21}$ atoms of carbon $= \frac{12.01}{6.022*10^{23} }$ × $7.75$ × $10^{21}$ g

= $0.154$ g

Hence, the mass in grams of $7.75$ × $10^{21}$ atoms of carbon is $0.154$ g.