Question #6a733
2 Answers
+294kJ
Explanation:
We will use Hess' Law to work out
(Normally an enthalpy cycle would be drawn but I do not know how to do that on a laptop so here is an alternative)
Hess' Law states that there is an indirect route along with the direct route in a reaction. We can use this indirect route to find the enthalpy change of the direct route.
Route A is the
Route B is the
Route C is the
We need to find route C which is A+B
224+436= 660kJ
660 - 72 = 588kJ
588kJ is for 2HBr but we only want HBr so we divide 588 by 2.
Warning! Long Answer.
Explanation:
You get the answer by applying Hess's Law.
You are given three equations:
From these, you must devise the target equation
The target equation has
When you reverse an equation, you change the sign of its
When you divide an equation by 2, you halve its
Equation (4) has
You need an equation with
Divide equation (1) by 2.
Equation (5) has
You need an equation with
Reverse equation (3) and divide it by 2.
Now, you add equations (4), (5) and (6), cancelling species that appear on opposite sides of the reaction arrows.
When you add equations, you add their
This gives us the target equation (7):