Question

a 6.55 g sample of aniline (\\(\text{c}_6\text{h}_5\text{nh}_2\\), molar mass = 93.13 g/mol) was combusted in a bomb calorimeter with a heat capacity of 14.25 kj/°c. if the initial temperature was 32.9°c, use the information below to determine the value of the final temperature of the calorimeter.

\\(4\text{c}_6\text{h}_5\text{nh}_2(\text{l}) + 35\text{o}_2(\text{g}) \
ightarrow 24\text{co}_2(\text{g}) + 14\text{h}_2\text{o}(\text{g}) + 4\text{no}_2(\text{g})\\)

\\(\delta h^{\circ}_{\text{rxn}} = -1.28 \times 10^4\text{ kj}\\)

257°c
46.6°c
48.7°c
41.9°c
931°c

question 12

when 1.50 mol of \\(\text{ch}_4(\text{g})\\) reacts with excess \\(\text{cl}_2(\text{g})\\) at constant pressure according to the chemical equation shown below, 1062 kj of heat are released. calculate the value of \\(\delta h\\) for this reaction, as written.

\\(2\text{ch}_4(\text{g}) + 3\text{cl}_2(\text{g}) \
ightarrow 2\text{chcl}_3(\text{l}) + 3\text{h}_2(\text{g})\\) \\(\delta h = ?\\)

-1420 kj
-708 kj
+708 kj
+1420 kj

Explanation:

Calculate moles of aniline reacted

Using the Stoichiometry knowledge point

$$ n = \frac{6.55\text{ g}}{93.13\text{ g/mol}} \approx 0.070332\text{ mol} $$

Determine heat released by aniline combustion

Using the Thermochemical Equations and Stoichiometry knowledge points

$$
LATEXBLOCK0
$$

Calculate final temperature of calorimeter

Using the Bomb Calorimetry and Calorimeter Heat Capacity knowledge points

$$
LATEXBLOCK1
$$

Scale enthalpy for the second reaction

Using the Thermochemical Equations and Stoichiometry knowledge points

$$
LATEXBLOCK2
$$

Answer:

Question 1

• (A) 257°C
• (B) 46.6°C
• (C) 48.7°C (Correct answer)
• (D) 41.9°C
• (E) 931°C

Question 2

• (A) -1420 kJ (Correct answer)
• (B) -708 kJ
• (C) +708 kJ
• (D) +1420 kJ