Question

The enthalpy of reaction for the decomposition of ammonium nitrate, NH4NO3 is -77.4 kJ mol^-1. Calculate the heat evolved when 78.8 g of water is formed from this reaction. Given: NH4NO3 (S)—> N2O+ 2H2O (g)

Answer 1

Answer:

- 169.42 kJ.

Explanation:

• We have the enthalpy of reaction for the decomposition of ammonium nitrate, NH₄NO₃, is - 77.4 kJ/mol.

• We need to calculate the no. of moles of NH₄NO₃ that will produce 78.8 g of H₂O.

• Firstly, we need to calculate the no. of moles of 78.8 g of H₂O produced using the relation:

n = mass/molar mass.

∴ n of H₂O = mass/molar mass = (78.8 g)/(18.0 g/mol) = 4.377 mol.

• From the balanced equation of the decomposition of NH₄NO₃:

NH₄NO₃ → N₂O + 2H₂O,

It is clear that every 1.0 mole of NH₄NO₃ decomposes to 1.0 mole of N₂O and 2.0 moles of H₂O.

Using cross multiplication:

1.0 mole of NH₄NO₃ decomposes into → 2.0 moles of H₂O.

??? mole of NH₄NO₃ decomposes into → 4.377 moles of H₂O.

∴ The no. of moles of NH₄NO₃ that will produce 78.8 g of H₂O = (1.0 mol)(4.377 mol)/(2.0 mol) = 2.188 mol.

• To get the heat evolved when 2.188 mol of NH₄NO₃ decomposed:

1.0 mole of NH₄NO₃ gives → - 77.4 kJ/mol.

∴ The heat evolved when 78.8 g of water is formed from this reaction = (no. of moles of NH₄NO₃)(heat evolved from decomposition of 1.0 mole of NH₄NO₃) = (2.188 mol)(- 77.4 kJ/mol) = - 169.42 kJ.

Answer 2

The study of chemicals and bonds is called chemistry. There are two types of elements in the periodic table and these are metals and nonmetals.

The correct answer is -169.42 kJ.

What is decomposition reaction?

• Chemical decomposition, or chemical breakdown, is the process or effect of simplifying a single chemical entity into two or more fragments.
• Chemical decomposition is usually regarded and defined as the exact opposite of chemical synthesis.

We have the enthalpy of reaction for the decomposition of ammonium nitrate, NH₄NO₃, which is - 77.4 kJ/mol. We need to calculate the no. of moles of NH₄NO₃ that will produce 78.8 g of H₂O.

Firstly, we need to calculate the no. of moles of 78.8 g of H₂O produced using the relation:

n = $\frac{mass}{molar\ mass}$

n of H₂O = $\frac{(78.8 g)}{(18.0)} = 4.377 mol.$

From the balanced equation of the decomposition of NH₄NO₃:

$NH_4NO_3 ----> N_2O + 2H_2O,$

It is clear that every 1.0 mole of NH₄NO₃ decomposes to 1.0 moles of N₂O and 2.0 moles of H₂O.

Using cross multiplication:

1.0 mole of NH₄NO₃ decomposes into → 2.0 moles of H₂O.

The no. of moles of NH₄NO₃ that will produce 78.8 g of H₂O = (1.0 mol)

$\frac{(4.377)}{(2.0)} = 2.188 mol.$

To get the heat evolved when 2.188 mol of NH₄NO₃ decomposed:

1.0 mole of NH₄NO₃ gives → - 77.4 kJ/mol.

The heat evolved when 78.8 g of water is formed from this reaction

= (no. of moles of NH₄NO₃)(heat evolved from the decomposition of 1.0 mole of NH₄NO₃)

= (2.188 mol)(- 77.4 kJ/mol) = - 169.42 kJ.

Hence, the correct answer is -169.42.

For more information about the decomposition reaction, refer to the link:-

https://brainly.com/question/16759172