Question

The value of AH rxn for the following reaction is -72 kJ. How many kJ of heat is released when 0.989 g of HBr (80.91 g/mol) is formed? H2 (g) + Br2 (g) -› 2 HBr (gram). A. -144B. -72 C. -0.44 D. -36

Answer 1

`C\text{ : -0.44 KJ}`

Step-by-step explanation:

Here, we want to get the amount of heat released in KJ

From the change in enthalpy given and the equation of reaction, we know that 2 moles of HBr would lead to that amount of heat

Now, let us get the actual amount of heat released

We need to get the actual number of moles of HBr produced

Mathematically, we can calculate that by dividing the mass of HBr by its molar mass

We have that as:

`(0.989)/(80.91)\text{ = 0.0122 mol}`

From the reaction information:

-72 KJ was released by 2 moles

x KJ would be released by 0.0122 mol

To get the value of x, we have it that:

`\begin{gathered} x\text{ }*2\text{ = 0.0122 }*\text{ \lparen-72\rparen} \\ \\ x\text{ = -36 }*\text{ \lparen0.0122\rparen = -0.44 KJ} \end{gathered}`