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) The number of molecules will be,

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

Solution :

(1) As, 1 mole contains number of molecules

So, 7 moles contains number of molecules

Therefore, the number of molecules will be,

(2) Number of atoms of magnesium chloride =

In one magnesium chloride molecule there are two chlorine atoms.

Number of chlorine atoms in atoms of magnesium chloride =

1 mole = atoms

Moles of chlorine =

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

"standard molar enthalpy:

h2o ( liquid water ) : - 285.8 kj/mole

h2o ( water vapor ) : - 241.8 kj / mole.

δhrxn = - 241. 8 - ( - 285.8 )= -241.8 + 285.8 = 44.0

answer: 44.0 kj"