<u>Given:</u>
Mass of Ag = 1.67 g
Mass of Cl = 2.21 g
Heat evolved = 1.96 kJ
<u>To determine:</u>
The enthalpy of formation of AgCl(s)
<u>Explanation:</u>
The reaction is:
2Ag(s) + Cl2(g) → 2AgCl(s)
Calculate the moles of Ag and Cl from the given masses
Atomic mass of Ag = 108 g/mol
# moles of Ag = 1.67/108 = 0.0155 moles
Atomic mass of Cl = 35 g/mol
# moles of Cl = 2.21/35 = 0.0631 moles
Since moles of Ag << moles of Cl, silver is the limiting reagent.
Based on reaction stoichiometry: # moles of AgCl formed = 0.0155 moles
Enthalpy of formation of AgCl = 1.96 kJ/0.0155 moles = 126.5 kJ/mol
Ans: Formation enthalpy = 126.5 kJ/mol
I'm assuming you need to know the percentage yield of the reaction
To calculate the percentage yield = (actual yield x 100%) / predicted yield
actual yield is 56,9 g
predicted yield is 36,6g ( is the amount that's expected if nothing had got lost)
(56,9 x100)/36,6=
= 155%
Yes, it would be considered as physical change.
Subscripts cannot be changed because they are the ratio of the amount. And as we know, in a chemical equation/reaction, mass cannot be created nor destroyed. Therefore, we cannot change subscripts, however, we could change coefficients. <span />
