Question

One million atoms of a particular element have a mass of 1.99 x 10 ^-17 grams.
- How many moles of this element are there?
- What is the molar mass of this element?
- What is the identity of this element?

Answer 1

- How many moles of this element are there?
1000000 atoms ( 1 mol / 6.022x10^23 atoms ) = 1.66 x 10^-18 mol of the element

- What is the molar mass of this element?
Molar mass =  1.99 x 10 ^-17 grams / 1.66 x 10^-18 mol = 11.98 g/mol

- What is the identity of this element?
The identity most likely is closest to carbon which has a molar mass of 12.01 g/mol.

Answer 2

Answer:

Moles of this element =$1.660\times 10^{-18}$ moles

The molar mass of this element  is 12 g/mol.

Carbon is the identity of this element.

Explanation:

Number of atom = 1,000,000

Number of atoms = $moles \times N_A$

$1,000,000 =moles\times 6.022\times 10^{23}$

$moles=1.660\times 10^{-18}$

Moles of this element =$1.660\times 10^{-18}$ moles

If $1.660\times 10^{-18}$ moles weighs =  $1.99 \times 10^{-17} g$

Then mass of 1 mol = $\frac{1.99 \times 10 ^{-17} g}{1.660\times 10^{-18}}=11.98 g\approx 12 g$

The molar mass of this element  is 12 g/mol.

Carbon is the identity of this element.