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

Moles of this element =
`1.660* 10^(-18)` moles

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

Carbon is the identity of this element.

Step-by-step explanation:

Number of atom = 1,000,000

Number of atoms =
`moles * N_A`

`1,000,000 =moles* 6.022* 10^(23)`

`moles=1.660* 10^(-18)`

Moles of this element =
`1.660* 10^(-18)` moles

If
`1.660* 10^(-18)` moles weighs =
`1.99 * 10^(-17) g`

Then mass of 1 mol =
`(1.99 * 10 ^(-17) g)/(1.660* 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.

Answer 2

- 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.