Question 1

Explain the differences between a bomb calorimeter and a cone calorimeter.

Accepted Answer

A bomb calorimeter and a cone calorimeter are both used to measure the heat release and combustion characteristics of materials, but they have different designs and applications.

A bomb calorimeter is a closed vessel used to measure the heat of combustion of a sample. It consists of a strong metal container (the bomb) in which the sample is placed, along with an excess of oxygen. The bomb is then placed in a container of water, and the sample is ignited with an electric current. The heat released from the combustion of the sample raises the temperature of the water, and this temperature change is used to calculate the heat of combustion.

On the other hand, a cone calorimeter is an open vessel used to measure the heat release rate, smoke production, and mass loss rate of a material when exposed to a controlled heat source. It consists of a sample holder in the shape of a cone, which is placed in a furnace and exposed to a heat flux. As the sample combusts, the heat release rate, smoke production, and mass loss rate are measured and recorded.

In summary, the main differences between a bomb calorimeter and a cone calorimeter are their design and the parameters they measure. A bomb calorimeter is used to measure the heat of combustion of a sample in a closed vessel, while a cone calorimeter is used to measure the heat release rate, smoke production, and mass loss rate of a material in an open vessel when exposed to a controlled heat source.

Question 2

Determine how much heat is required to increase the temperature of a 495.0 g sample of acetone from 58°C to its autoignition temperature of 465°C, given that the specific heat capacity of acetone is 1.20 J/g·°C.

Accepted Answer

2.4 × 10⁵ J

Question 3

What physical process is happening between points E and F?

Accepted Answer

D

Question 4

Calculate the specific heat capacity in J/kg·°C of an unknown metal in a 3.76 kg block that requires 1.83 × 10⁴ J of heat to raise the temperature from 23.8°C to 61.2°C.

Accepted Answer

The answer of Calculate the specific heat capacity in J/kg·°C...

Question 5

Compounds with which type of intermolecular force will tend to have large heats of vaporization?

Accepted Answer

Hydrogen bonding is a strong type of dipole-dipole interaction that occurs when hydrogen is bonded to a highly electronegative atom (such as nitrogen, oxygen, or fluorine), leading to large heats of vaporization due to the significant energy required to overcome these interactions.

Question 6

A 0.500 g sample of TNT (C₇H₅N₂O₆) is ignited in a bomb calorimeter and the temperature of 610 mL of water increases from 20.0°C to 23.0°C. What is the heat of combustion (J/g) of the TNT?

Accepted Answer

The answer of A 0.500 g sample of TNT (C₇H₅N₂O₆)...

Question 7

Convert 76.2 Calories to kilojoules.

Accepted Answer

The answer of Convert 76.2 Calories to kilojoules.
...

Question 8

A 28.4 g sample of aluminum, initially at 39.4°C, heated 50.0 g of water from 22.0°C to 24.0°C upon being submerged in the water. Determine the specific heat of aluminum, given that the specific heat of water is 4.184 J/g·°C.

Accepted Answer

The answer of A 28.4 g sample of aluminum, initially...

Question 9

Which element is oxidized in the following reaction? 10I^- + 16H⁺ + 2MnO₄^- → 5I₂ + 2Mn²⁺ + 8H₂O

Accepted Answer

Iodine (I) is oxidized as it goes from a -1 oxidation state in the reactants to a 0 oxidation state in the products.

Question 10

What physical process is happening between points B and C?

Accepted Answer

The answer of What physical process is happening between points...

Question 11

Write and balance the equation for the complete combustion of pentane.

Accepted Answer

The answer of Write and balance the equation for the...

Question 12

Which element is reduced in the following reaction? 4Ag(s) + 2H₂S(g) + O₂(g) → 2Ag₂S(s) + 2H₂O(g)

Accepted Answer

In the given reaction, oxygen (O) is reduced as it gains electrons, going from a 0 oxidation state in O2 to a -2 oxidation state in H2SO4.

Question 13

Indicate whether the following statement is true or false
-Temperature is a measure of the heat content of a body.

Accepted Answer

Temperature is a measure of the average kinetic energy of the particles in a substance, not a measure of its total heat content.

Question 14

In which type of reaction do the products have more energy than the reactants?

Accepted Answer

In an endothermic reaction, the products have more energy than the reactants because energy is absorbed from the surroundings during the reaction.

Question 15

Write and balance the equation for the complete combustion of C₆H₁₄.

Accepted Answer

The answer of Write and balance the equation for the...

Question 16

What is the oxidation number of Mn in the compound Mn₂S₃?

Accepted Answer

In Mn₂S₃, sulfur typically has an oxidation number of -2. Since there are three sulfur atoms, the total negative charge is -6. To balance this, the total positive charge from two manganese atoms must be +6, making the oxidation number of each Mn atom +3.

Question 17

What is the initial temperature of a 13.5 g sample of gold if it raises the temperature of 60.0 g of water from 19.5°C to 20.5°C upon submersion? The specific heat of gold is 0.13 J/g·°C and of water is 4.184 J/g·°C.

Accepted Answer

The answer of What is the initial temperature of a...

Question 18

What is the oxidation number of Hg in Hg₂Cl₂?

Accepted Answer

In Hg2Cl2, mercury exists as a diatomic ion (Hg2^2+), where each Hg has an oxidation state of +1. Chlorine has an oxidation state of -1, and the compound is neutral overall.

Question 19

Convert the heat of combustion of ethanol, 7.1 Cal/g, to J/g.

Accepted Answer

The conversion factor from calories to joules is 4.184 J/Cal. Therefore, to convert 7.1 Cal/g to J/g, multiply 7.1 by 4.184 to get approximately 29.7 J/g, which is closest to 3.0 × 10^4 J/g.

Quiz 9: Chemistry of Fire and Heat

Explain the differences between a bomb calorimeter and a cone calorimeter.

Determine how much heat is required to increase the temperature of a 495.0 g sample of acetone from 58°C to its autoignition temperature of 465°C, given that the specific heat capacity of acetone is 1.20 J/g·°C.

What physical process is happening between points E and F?

Calculate the specific heat capacity in J/kg·°C of an unknown metal in a 3.76 kg block that requires 1.83 × 104 J of heat to raise the temperature from 23.8°C to 61.2°C.

Compounds with which type of intermolecular force will tend to have large heats of vaporization?

A 0.500 g sample of TNT (C7H5N2O6) is ignited in a bomb calorimeter and the temperature of 610 mL of water increases from 20.0°C to 23.0°C. What is the heat of combustion (J/g) of the TNT?