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Which of the reactions are exothermic? Agcl(s)⟶ag+(aq)+cl−(aq) δh=127 kj/mol nh3(g)+hcl(g)⟶nh4cl(s) δh=−176 kj/mol 2fe2o3(s)+3c(s)⟶4fe(s)+3co2(g) δh=468 kj/mol 2mg(s)+o2(g)⟶2mgo(s) δh=−1203 kj/mol c(graphite)+o2(g)⟶co2(g) δh=−393.5 kj/mol ch4(g)+2o2(g)⟶co2(g)+2h2o(l)δh=−891 kj/mol?

Respuesta :

Exothermic reactions are chemical reactions that proceed with the release of heat energy. I contrast, endothermic reactions involve absorption of heat.

The enthalpy change (ΔH) for exothermic reactions is negative while that of endothermic reactions is positive.

In the given examples, reactions that show a negative ΔH are:

NH3 + HCl ------- NH4Cl  ΔH = -176 KJ/mol

2Mg + O2 -------- 2MgO  ΔH = -1203 kj/mol

C + O2 ---- CO2 ΔH = -393.5 kj/mol

CH4 + 2O2 ----------------- CO2 + 2H2O  ΔH = -891 kj/mol

Exothermic reactions are defined as the reactions that evolves or releases heat energy. On the other hand, endothermic reactions are those in which heat energy is involved.

The equations given in the questions are endothermic or exothermic. The value of [tex]\Delta[/tex]H if is positive, then the equation will be endothermic. If the value of [tex]\Delta[/tex]H is negative then it will be an exothermic reactions.

The exothermic equations are:

Exothermic:

  • [tex]\text {NH}_{3} + \text {HCl} \rightarrow \; {\text {NH}_{4}\text{Cl}\; \Delta \text H = -176 \text{KJ/mol}[/tex]
  • [tex]2\text{Mg + O}_{2}\rightarrow\; 2\text{MgO}\;\Delta\textH = -1203 \;\text{\;kj/mol}[/tex]
  • [tex]\text {C+O}_{2}\rightarrow\; \text{CO}_{2}\;\Delta \text H = -393.5\text{kj/mol}[/tex]
  • [tex]\text {CH}_{4} + \text {2 O}_{2} \rightarrow \; {\text {CO}_{2}+\text{2 H}_{2}\text {O}\; \Delta \text H = -891 \text{KJ/mol}[/tex]

Therefore, the exothermic equations can be identified by the negative enthalpy change in the reaction.

To know more about the exothermic reactions, refer to the following link:

https://brainly.com/question/14053515?referrer=searchResults

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