Question

question 20 (1 point)
which of the following represents an exothermic reaction?
\\( \mathrm{s}_{(s)} + \mathrm{o}_{2(g)} \
ightarrow \mathrm{so}_{2(g)} \quad \delta h = -297 \text{ kj} \\)
\\( \mathrm{n}_{2(g)} + 2\mathrm{o}_{2(g)} + 33.8 \text{ kj} \
ightarrow 2\mathrm{no}_{2(g)} \\)
\\( \mathrm{n}_{2(g)} + 2\mathrm{o}_{2(g)} \
ightarrow 2\mathrm{no}_{2(g)} \quad \delta h = 90.4 \text{ kj} \\)
\\( \mathrm{caco}_{3(s)} \
ightarrow \mathrm{cao}_{(s)} + \mathrm{co}_{2(g)} \quad \delta h = 177.7 \text{ kj} \\)

question 21 (1 point)
consider the reaction:
\\( 2\mathrm{bao} + \text{energy} \
ightarrow 2\mathrm{ba} + \mathrm{o}_2 \\)
this reaction may be classified as a
neutralization reaction
synthesis reaction
endothermic reaction
exothermic reaction

Explanation:

Identify exothermic reaction criteria

An exothermic reaction releases heat to the surroundings.
In thermochemical equations, this is represented by:

• A negative enthalpy change: \(\Delta H < 0\)
• Energy written as a product on the right side.

Analyze Question 20 options

Let's evaluate each given option:

• Option 1: \(\text{S}_{(s)} + \text{O}_{2(g)}

ightarrow \text{SO}_{2(g)} \quad \Delta H = -297\text{ kJ}\)
Since \(\Delta H\) is negative, this reaction is exothermic.

• Option 2: \(\text{N}_{2(g)} + 2\text{O}_{2(g)} + 33.8\text{ kJ}

ightarrow 2\text{NO}_{2(g)}\)
Energy is on the reactant side, meaning it is endothermic.

• Option 3: \(\text{N}_{2(g)} + 2\text{O}_{2(g)}

ightarrow 2\text{NO}_{2(g)} \quad \Delta H = 90.4\text{ kJ}\)
Since \(\Delta H\) is positive, this reaction is endothermic.

• Option 4: \(\text{CaCO}_{3(s)}

ightarrow \text{CaO}_{(s)} + \text{CO}_{2(g)} \quad \Delta H = 177.7\text{ kJ}\)
Since \(\Delta H\) is positive, this reaction is endothermic.

Analyze Question 21 reaction

We are given the following chemical equation:

$$2\text{BaO} + \text{energy} ightarrow 2\text{Ba} + \text{O}_2$$

Energy is written on the reactant (left) side.
This means energy is absorbed during the chemical process.

Classify Question 21 reaction

A reaction that absorbs energy is classified as endothermic.
Therefore, this reaction is an endothermic reaction.

Answer:

Question 20

• **(A) \(\text{S}_{(s)} + \text{O}_{2(g)}

ightarrow \text{SO}_{2(g)} \quad \Delta H = -297\text{ kJ}\) (Correct answer)**

• (B) \(\text{N}_{2(g)} + 2\text{O}_{2(g)} + 33.8\text{ kJ}

ightarrow 2\text{NO}_{2(g)}\)

• (C) \(\text{N}_{2(g)} + 2\text{O}_{2(g)}

ightarrow 2\text{NO}_{2(g)} \quad \Delta H = 90.4\text{ kJ}\)

• (D) \(\text{CaCO}_{3(s)}

ightarrow \text{CaO}_{(s)} + \text{CO}_{2(g)} \quad \Delta H = 177.7\text{ kJ}\)

Question 21

• (A) neutralization reaction
• (B) synthesis reaction
• (C) endothermic reaction (Correct answer)
• (D) exothermic reaction