What is the standard enthalpy change for the reaction?
Given the standard enthalpy changes for the following two reactions:
(1) Zn(s) + Cl2(g)ZnCl2(s)...... ΔH° = -415.0 kJ
(2) Pb(s) + Cl2(g)PbCl2(s)......ΔH° = -359.4 kJ
what is the standard enthalpy change for the reaction:
(3) Zn(s) + PbCl2(s)ZnCl2(s) + Pb(s)......ΔH° = ?
Given the standard enthalpy changes for the following two reactions:
(1) Zn(s) + Cl2(g)ZnCl2(s)...... ΔH° = -415.0 kJ
(2) Pb(s) + Cl2(g)PbCl2(s)......ΔH° = -359.4 kJ
what is the standard enthalpy change for the reaction:
(3) Zn(s) + PbCl2(s)ZnCl2(s) + Pb(s)......ΔH° = ?
2 Answers
Explanation:
What you have
You have two equations:
From these, you must devise the target equation:
What you must do
The target equation has
Equation (4) has
You need an equation with
Reverse Equation (2).
When you reverse an equation, you reverse the sign of its
Now, you add equations (4) and (5), cancelling species that appear on opposite sides of the reaction arrows.
When you add equations, you add their
This gives the target equation (6):