For which of the following reactions is δh∘rxn equal to δh∘f of the product(s)?

choose all that apply.
a. c(s, graphite)+o2(g)→co2(g)
b. li(s)+12cl2(g)→licl(s)
c. li(s)+12cl2(l)→licl(s)
d. 2li(s)+cl2(g)→2licl(s)
e. co(g)+12o2(g)→co2(g)
f. baco3(s)→bao(s)+co2(g)

The change in enthalpy in the formation of 1 mole of the elements is called enthalpy of formation

The enthalpy of formation measured in standard conditions (25 ° C, 1 atm) is called the standard enthalpy of formation (ΔHf °)

Determination of the enthalpy of formation of a reaction can be through a calorimetric experiment, based on the principle of Hess's Law, enthalpy of formation table, or from bond energy data

Delta H reaction (ΔH) is the amount of heat / heat change between the system and its environment

(ΔH) can be positive (endothermic = requires heat) or negative (exothermic = releasing heat)

The value of ° H ° can be calculated from the change in enthalpy of standard formation:

∆H ° rxn = ∑n ∆Hf ° (product) - ∑n ∆Hf ° (reactants)

ΔH∘rxn = ΔH∘f of the product(s) if ∆Hf ° (reactants)  = 0

The elements in standard conditions are not included in the enthalpy calculations because the enthalpy of those elements under the standard conditions is zero.

a.ΔH°rxn = ∆Hf ° CO₂(∆Hf °C and ∆Hf °O₂ =0)

b.ΔH°rxn = ∆Hf ° LiCl(∆Hf °Li and ∆Hf °Cl₂=0)

c.ΔH°rxn = ∆Hf ° LiCl- 12∆Hf° Cl₂

d. ΔH°rxn = 2∆Hf °LiCl (∆Hf °Li and ∆Hf °Cl₂=0)

e. ΔH°rxn = ∆Hf °CO₂ - ∆Hf °CO

f. ΔH°rxn = ∆Hf °CO₂ + ∆Hf °BaO - ∆Hf ° BaCO₃

Delta H solution

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an exothermic reaction

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as endothermic or exothermic

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an exothermic dissolving process

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Keywords: Delta H reaction (ΔH), enthalpy of standard formation

the correct answer is:

a. formation of precipitation