Question

1. 3.000 grams of Ca is burned in a bomb calorimeter. The
water’s temperature rose from 20.0 degrees centigrade to 21.79
degrees centigrade. The heat capacity of the calorimeter is 26.60
kJ/C. What is the enthalpy change for this reaction as written. The
thermochemical equation is:

2Ca (s) + O2 (g) —> 2CaO (s)

2. 1.30 grams of C7H6O2 is combusted in a bomb calorimeter.
The water’s temperature rose from 20.00 degrees centigrade to 21.58
degrees centigrade. The heat capacity of the calorimeter is 10.90
kJ/C. What is the enthalpy change for this reaction. The
thermochemical reaction is:

2C7H6O2 + 15O2 —> 14CO2 + 6H2O

3. 0.560 grams of C6H6 is burned in a bomb calorimeter. The
water rises in temperature from 22.0 degrees centigrade to 29.90
degrees centigrade. The heat capacity of the calorimeter (bomb plus
water) is 2.96 kJ/C. What is the enthalpy change for the combustion
of one mole of C6H6? The thermochemical equation is:

C6H6 (l) + 15/2O2 —> 6CO2 (g) + 3H2O (l)

Answer #1

1):

Moles of Ca = Mass of Ca/ atomic mass of Ca = 3.000 g/(40.078 g/mol) = 0.07485 mol

Heat of calorimeter (q_{cal}) = heat capacity of
calorimeter x temperature change

= (26.60 kJ/^{o}C) x (21.79 ^{o}C - 20.0
^{o}C)

= 47.61 kJ

Enthalpy change of the reaction = - q_{cal} /mol Ca = -
47.61 kJ/0.07485 mol = **- 636 kJ/mol**

When 2.25mg of anthracene was combusted in a constant volume
bomb calorimeter, the temperature rose by 1.35K. Given that the
standard molar enthalpy of combustion of anthracene at 298K is
-7061 kJ/mol, calculate the heat capacity of the calorimeter.

A 1.000 g sample of octane (C8H18) is burned in a bomb
calorimeter containing 1200 grams of water at an initial
temperature of 25.00ºC. After the reaction, the final temperature
of the water is 33.20ºC. The heat capacity of the calorimeter (also
known as the “calorimeter constant”) is 837 J/ºC. The specific heat
of water is 4.184 J/g ºC. Calculate the heat of combustion of
octane in kJ/mol.

A 0.373-g sample of naphthalene (C10H8) is burned in a bomb
calorimeter and the temperature increases from 24.90 °C to 27.80
°C. The calorimeter contains 1.05E3 g of water and the bomb has a
heat capacity of 836 J/°C. Based on this experiment, calculate ΔE
for the combustion reaction per mole of naphthalene burned
(kJ/mol).

A 0.287-g sample of bianthracene (C28H18) is burned in a bomb
calorimeter and the temperature increases from 25.30 °C to 27.50
°C. The calorimeter contains 1.03E3 g of water and the bomb has a
heat capacity of 856 J/°C. Based on this experiment, calculate ΔE
for the combustion reaction per mole of bianthracene burned
(kJ/mol).

A 0.553-g sample of diphenyl
phthalate
(C20H14O4) is
burned in a bomb calorimeter and the temperature increases from
24.40 °C to 27.57 °C. The
calorimeter contains 1.08×103 g of
water and the bomb has a heat capacity of 877
J/°C. The heat capacity of water is 4.184 J
g-1°C-1. Based on this experiment, calculate
ΔE for the combustion reaction per mole of diphenyl
phthalate burned.
______ kJ/mol

. A 0.500 g sample of naphthalene (C10H8) is burned in a bomb
calorimeter containing 650 grams of water at an initial temperature
of 20.00 oC. After the reaction, the final temperature of the water
is 26.4ºC. The heat capacity of the calorimeter is 420 J/oC. Using
these data, calculate the heat of combustion of naphthalene in
kJ/mol.

A 1.000g sample of benzene (C6H6) is
burned in a bomb calorimeter whose total heat capacity is 4.957 kJ/
oC. If the temperature of the calorimeter increases from
25.30 to 33.74 oC , what is the heat of combustion of
the benzene per mole.
Explanation please.

A quantity of 1.922 g of methanol (CH3OH) was
burned in a constant-volume bomb calorimeter. Consequently, the
temperature rose by 5.56°C. If the heat capacity of the bomb plus
water was 8.09 kJ /
°C, calculate the molar
heat of combustion of methanol.

A 2.50 mol sample of benzene (C6H6, 78.11 g/mol) was burned in a
bomb calorimeter with a heat capacity of 800 J/°C. The calorimeter
contained 100g of water (4.18J/g°C) and the temperature increased
by 4°C. What is the molar enthalpy of combustion for this
compound?

Sulfur (2.56 g) is burned in a bomb calorimeter with excess
O2(g). The temperature increases from 21.25 °C to 26.72 °C. The
bomb has a heat capacity of 923 J/K, and the calorimeter contains
815 g of water.
Calculate the heat evolved, per mole of SO2 formed, in the
course of the reaction:
S8(s) + 8 O2(g) --> 8 SO2(g)
Answer is in kJ.
A. 301.2
B. 3410
C. 296.3
D. 145.1

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