Question

Calculate the number of moles of Cl atoms in 1.81×10^24 formula units of magnesium chloride,MgCl2.

Answer 1

Answer: The number of moles of Chlorine atoms in given formula units of magnesium chloride are 6 moles.

Step-by-step explanation:

Formula unit is defined as lowest whole number ratio of ions in an ionic compound. It is calculate by multiplying the number of moles by Avogadro's number which is
`6.022* 10^(23)`

We are given:

Number of formula units of magnesium chloride =
`1.81* 10^(24)`

By applying unitary method, we get:

If
`6.022* 10^(23)` number of formula units are present in 1 mole of a compound.

So,
`1.81* 10^(24)` number of formula units will be present in
`(1)/(6.022* 10^(23))* 7.81* 10^(24)=3mol` of magnesium chloride.

For the given compound magnesium chloride:

As, 1 mole of magnesium chloride contains 1 mole of magnesium atom and 2 atoms of chlorine atoms.

So, 3 moles of magnesium chloride will contain
`(1* 3)=3mol` of magnesium atoms and
`(2* 3)=6mol` of chlorine atoms.

Hence, the number of moles of Chlorine atoms in given formula units of magnesium chloride are 6 moles.

Answer 2

Avogadro's number represents the number of units in one mole of any substance. This has the value of 6.022 x 10^23 units / mole. This number can be used to convert the number of atoms or molecules into number of moles. We calculate as follows:

1.81×10^24 formula units MgCl2 ( 1 mol / 6.022x10^23 formula units ) ( 2 mol Cl / 1 mol MgCl2 ) = 6.01 mol Cl atoms