Question

1.Hess's Law ProblemsCalculate the AH for the reaction CHa (g) + Ha (g) - C»He (g), from the following:a.CHa (g) + 3 0, (g) › 2 CO, (g) + 2 H,0 (1)2 C_Ho (g) + 7 02 (g) - 4 COz (g) + 6 H,0 (1)C.2 H2 (g) + 02 (g)-2 H,0 (1)IAH = - 1411. kJAH = - 3120. kJAH = - 571.6 kJ

Answer 1

ΔH for the reaction is +12.2 kJ

Step-by-step explanation

Given:

The given reaction is:

The following are the given data:

What to find:

To calculate the ΔH for the given reaction.

Step-by-step solution:

Step 1: Multiply (a) through by 2

`\begin{gathered} a.\text{ }C_2H_4(g)+3O_2(g)\rightarrow2CO_2(g)+2H_2O(l)*2\text{ }\Delta H=-1411\text{ }kJ*2 \\ \\ a.\text{ }2C_2H_4(g)+6O_2(g)\rightarrow4CO_2(g)+4H_2O(l)\text{ }\Delta H=-2822\text{ }kJ \end{gathered}`

Step 2: Reverse (b)

`\begin{gathered} b.\text{ }2C_2H_6(g)+7O_2(g)\rightarrow4CO_2(g)+6H_2O(l)\text{ }\Delta H=-3120\text{ }kJ \\ \\ Reverse\text{ }the\text{ }equation \\ \\ b.\text{ }4CO_2\left(g\right)+6H_2O\left(l\right)\rightarrow2C_2H_6\left(g\right)+7O_2\left(g\right)\text{ }\Delta H=+3120\text{ }kJ \end{gathered}`

Step 3: (c)

`c.\text{ }2H_2(g)+O_2(g)\rightarrow2H_2O(l)\text{ }\Delta H=-571.6\text{ }kJ`

Step 4: Combine (a), (b), and (c) and simplify.

`\begin{gathered} 2C_2H_4(g)+6O_2(g)+4CO_2\left(g\right)+6H_2O\left(l\right)+2H_2(g)+O_2(g)\rightarrow \\ \\ 4CO_2(g)+4H_2O(l)+2C_2H_6\left(g\right)+7O_2\left(g\right)+2H_2O(l) \\ \\ \Delta H=(-2822\text{ }kJ+3120\text{ }kJ-571.6\text{ }kJ)-(-3120\text{ }kJ+2822\text{ }kJ) \\ \\ Simplify\text{ }the\text{ }equation \\ \\ 2C_2H_4(g)+2H_2(g)\rightarrow2C_2H_6\left(g\right)\text{ }\Delta H=(-273.6\text{ }kJ)-(-298\text{ }kJ) \\ \\ 2C_2H_4(g)+2H_2(g)\rightarrow2C_2H_6\left(g\right)\text{ }\Delta H=+24.4\text{ }kJ \end{gathered}`

Since the given equation is in 1 mole, then divide through by 2

Therefore, ΔH for the given reaction is +12.2 kJ