Need help with conversion

[parisnicole1989]

Hey! Please help me if you can....Here is the problem:
How many liters of Cl₂ gas at 25C and 745 torr could be prepared from 7.2g HCl according to the following reaction? 4HCl +MnO₂=2H₂O+MnCl₂+Cl₂
Also....can someone explain why aluminum chloride is predominately covalent while aluminum fluoride is predominately ionic.

[Simon]

Hey! Please help me if you can....Here is the problem:
How many liters of Cl₂ gas at 25C and 745 torr could be prepared from 7.2g HCl according to the following reaction? 4HCl +MnO₂=2H₂O+MnCl₂+Cl₂

1) Calculate number of moles of HCl from it's mass.
n(HCl) = m(HCl) / M(HCl)
2) Calculate number of moles of Cl₂ (in according to the reaction)
n(Cl₂) = n(HCl) / 4
3) Convert pressure from torr to atm
P[atm]= P[torr] / 760
4) Calculate volume of Cl₂
V(Cl₂) = n(Cl₂) * R * T / P[atm] (R=0.082058 L*atm*mol-1*K-1)
You will get the volume in liters.

Also....can someone explain why aluminum chloride is predominately covalent while aluminum fluoride is predominately ionic.

That's because the difference in electronegativities of F and Al is bigger than for Cl and Al.
"Electronegativity is a measure of the tendency of an atom to attract a bonding pair of electrons."