Question

Calculate the number of molecules in 7.00 moles H2S.

Calculate the number of moles of Cl atoms in 1.81 x10^24 units of magnesium chloride,MgCl2.

Answer 1

One mole has 6.02*10^23 so 7 moles has 6.02*10^23 * 7 or 4.21*10^24

For the second part you do:
6.02*10^23/1.81*10^24 and get 3 moles of MgCl2, so there are 3 moles of Cl atoms

Hope this helps

Answer 2

Answer : (1) The number of molecules will be,
`42.154* 10^(23)`

(2) The number of moles of chlorine atoms is, 6.0112 moles

Solution :

(1) As, 1 mole
`H_2S` contains
`6.022* 10^(23)` number of molecules

So, 7 moles
`H_2S` contains
`7* 6.022* 10^(23)=42.154* 10^(23)` number of molecules

Therefore, the number of molecules will be,
`42.154* 10^(23)`

(2) Number of atoms of magnesium chloride =
`1.81* 10^(24)`

In one magnesium chloride molecule there are two chlorine atoms.

Number of chlorine atoms in
`1.81* 10^(24)` atoms of magnesium chloride =
`2* 1.81* 10^(24)=3.62* 10^(24)`

1 mole =
`6.022* 10^(23)` atoms

Moles of chlorine =
`(3.62* 10^(24))/(6.022* 10^(23))=6.0112moles`

Therefore, the number of moles of chlorine atoms is, 6.0112 moles