Match each chemical process on the left with its corresponding thermodynamic energy classi… — JAMB UTME

Match each chemical process on the left with its corresponding thermodynamic energy classification and enthalpy characteristics on the right.

Dissolution of ammonium chloride in water ( $NH_4Cl_{(s)} \xrightarrow{H_2O} NH_{4(aq)}^+ + Cl_{(aq)}^-$ )Endothermic dissolution ( $\Delta H > 0$ ), where heat is absorbed from the surroundings, resulting in a temperature drop of the solution.
Combustion of methane gas ( $CH_{4(g)} + 2O_{2(g)} \rightarrow CO_{2(g)} + 2H_2O_{(l)}$ )Exothermic combustion ( $\Delta H < 0$ ), where bond formation in products releases substantial thermal energy to the surroundings.
Neutralization of hydrochloric acid with sodium hydroxide ( $HCl_{(aq)} + NaOH_{(aq)} \rightarrow NaCl_{(aq)} + H_2O_{(l)}$ )Exothermic neutralization ( $\Delta H < 0$ ), releasing heat as hydrogen ions react with hydroxide ions to form liquid water.
Thermal decomposition of calcium carbonate ( $CaCO_{3(s)} \xrightarrow{\Delta} CaO_{(s)} + CO_{2(g)}$ )Endothermic thermal decomposition ( $\Delta H > 0$ ), requiring continuous thermal energy input to break chemical bonds in the reactant.

Cevap

Dissolution of ammonium chloride matches Endothermic dissolution (absorbs heat causing solution temperature drop); Combustion of methane matches Exothermic combustion (releases heat energy into surroundings); Neutralization of acid and base matches Exothermic neutralization (releases heat during water formation); Thermal decomposition of calcium carbonate matches Endothermic thermal decomposition (requires continuous external heat input).

The pairs are assigned based on thermodynamic principles: reactions that absorb energy from their surroundings (ammonium chloride dissolution and calcium carbonate breakdown) are endothermic (

\Delta H > 0

), whereas reactions that release heat to their surroundings (methane combustion and acid-base neutralization) are exothermic (

\Delta H < 0

Adım Adım Çözüm

Identify whether each reaction absorbs or releases energy from its surroundings.

Dissolution of

NH_4Cl

and decomposition of

CaCO_3

absorb heat (

\Delta H > 0

). Combustion of

CH_4

and neutralization of

HCl/NaOH

evolve heat (

\Delta H < 0

Endothermic processes absorb heat from surroundings (

\Delta H > 0

), while exothermic processes release heat to surroundings (

\Delta H < 0

Pair dissolution of ammonium chloride with its thermodynamic behavior.

Matches 'Endothermic dissolution (

\Delta H > 0

), where heat is absorbed from the surroundings, resulting in a temperature drop of the solution.'

Lattice dissociation energy exceeds hydration energy in

NH_4Cl

dissolution, causing a cooling effect in the solution.

Pair combustion of methane gas with its thermodynamic behavior.

Matches 'Exothermic combustion (

\Delta H < 0

), where bond formation in products releases substantial thermal energy to the surroundings.'

Energy released upon forming

C=O

and

O-H

bonds is greater than energy required to break

C-H

and

O=O

bonds.

Pair acid-base neutralization with its thermodynamic behavior.

Matches 'Exothermic neutralization (

\Delta H < 0

), releasing heat as hydrogen ions react with hydroxide ions to form liquid water.'

The reaction

H^+_{(aq)} + OH^-_{(aq)} \rightarrow H_2O_{(l)}

has a standard enthalpy change of approximately

-57.3\text{ kJ mol}^{-1}

Pair thermal decomposition of calcium carbonate with its thermodynamic behavior.

Matches 'Endothermic thermal decomposition (

\Delta H > 0

), requiring continuous thermal energy input to break chemical bonds in the reactant.'

Thermal breakdown of limestone into calcium oxide and carbon dioxide requires continuous high-temperature heat input.

Anahtar Kavram

Classification and Enthalpy Changes of Exothermic and Endothermic Reactions

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