Question 1

Complete combustion of hydrocarbons or compounds with only C, H, and O gives CO₂ and H₂O as the only products. If carried out under standard conditions, the CO₂ is a gas and the H₂O is a liquid. Given these standard enthalpies of combustion: C₆H₁₂(l)= -3919.86 kJ mol^-1, C₆H₆(l)= -3267.80 kJ mol^-1, H₂(g)= -285.90 kJ mol^-1, C(s)= -393.50 kJ mol^-1, calculate $\Delta$H°_reactionfor the reaction,C₆H₆(l)+ 3 H₂(g)$\rarr$C₆H₁₂(l)Hint: Remember it is always products minus reactants when performing enthalpy calculations.

Accepted Answer

The enthalpy change for the reaction is calculated using the formula: ΔH°reaction = ΣΔH°f(products) - ΣΔH°f(reactants). For this reaction, ΔH°reaction = ΔH°f(C6H12) - [ΔH°f(C6H6) + 3ΔH°f(H2)]. Substituting the given values: ΔH°reaction = (-3919.86) - [(-3267.80) + 3(-285.90)] = -3919.86 + 3267.80 + 857.70 = -205.64 kJ.

Question 2

The energy transferred between objects caused by differences in their temperatures is called ________.

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Question 3

In the equation for the determination of the kinetic energy of an object, KE = mv², the 'm' in the equation represents its ________.

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Question 4

In order for a smaller motorcycle to have the same kinetic energy as a large SUV, the SUV would have to be traveling ________ than the motorcycle.

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Question 5

What is the mass of an object that has a kinetic energy of 1 J travelling at a speed of 1 m s⁻¹? ________.

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Question 6

The sum of the energies of all the individual particles in a sample of a substance is its ________.

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Question 7

When the Kelvin temperature of a sample of molecules increases, its average kinetic energy ________.

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Question 8

A 500.0 gram sample of water has an initial temperature of 25.0 °C. It absorbs 50.0 kJ of heat from its surroundings. What is its final temperature, in °C? Specific heat of water = 4.184 J g⁻¹ °C⁻⁻¹.

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Question 9

A sample of nickel weighing 425 grams was initially at a temperature of 26.20 °C. It required 975 joules of heat energy to increase the temperature to 31.55 °C. What is the specific heat of the nickel?

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Question 10

A sample of zinc weighing 425 grams was initially at a temperature of 25.40 ^°C. It required 1360 joules of heat energy to increase the temperature to 33.70 ^°C. What is the molar heat capacity of the zinc?Hint: Determine how many moles of zinc you have when doing this problem.

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Question 11

Reactions that consume energy are said to be ________.

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Question 12

In a chemical equation, heat can be written as a product. A chemical reaction in which heat is a product is described as ________.

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Question 13

In an exothermic reaction, energy is ________ the system.

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Question 14

In an endothermic reaction, energy is ________ the system.

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Question 15

The heat released or absorbed in a chemical reaction is called the ________.

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Question 16

In a gas-phase chemical reaction performed at constant volume, the heat absorbed by the insulated calorimeter was calculated to be 29.3 kJ. What is q_v for the reaction?

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Question 17

In a gas-phase chemical reaction performed at constant atmospheric pressure, the heat absorbed by the insulated calorimeter was calculated to be 19.8 kJ. What is q_p for the reaction?

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Question 18

When a chemical reaction occurs in a bomb calorimeter, the change in volume for the system, V, is equal to ________.

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Question 19

For a chemical reaction in which the change is endothermic, the sign of the enthalpy change, H, is ________.

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Question 20

At constant pressure, the difference between the enthalpy change, H, and the internal energy change, ΔE, is equal to ________.

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Quiz 7: Energy and Chemical Change