Fuels - U3 O1 Flashcards
What is the definition of a fuel?
A fuel is a substance that can be burned or consumed to produce energy.
True or False: Fossil fuels are derived from ancient organic materials.
True
Fill in the blank: Fossil fuels include _____, coal, and natural gas.
oil
What is a key characteristic that distinguishes biofuels from fossil fuels?
Biofuels are produced from renewable biological materials, whereas fossil fuels are non-renewable.
Multiple Choice: Which of the following is a type of biofuel? A) Coal B) Ethanol C) Natural gas
B) Ethanol
What are the two main categories of fuels?
Fossil fuels and biofuels.
True or False: Biofuels can be produced from food crops.
True
Short Answer: Name one environmental benefit of using biofuels.
Reduced greenhouse gas emissions.
Fill in the blank: The process of converting organic matter into biofuels is known as _____ production.
biofuel
Multiple Choice: Which of the following is NOT a fossil fuel? A) Petroleum B) Solar energy C) Natural gas
B) Solar energy
What is an exothermic reaction?
A reaction that releases energy in the form of heat.
What is an endothermic reaction?
A reaction that absorbs energy from its surroundings.
True or False: In exothermic reactions, the products have higher energy than the reactants.
False
Fill in the blank: In an endothermic reaction, the enthalpy change (ΔH) is __________.
positive
Fill in the blank: In an exothermic reaction, the enthalpy change (ΔH) is __________.
negative
What occurs during bond breaking in a chemical reaction?
Energy is absorbed to overcome the forces holding the atoms together.
What occurs during bond making in a chemical reaction?
Energy is released as new bonds form between atoms.
Which type of reaction typically has a decrease in temperature in the surroundings?
Endothermic reaction
Which type of reaction typically has an increase in temperature in the surroundings?
Exothermic reaction
True or False: All exothermic reactions are spontaneous.
False
What is the relationship between bond strength and enthalpy changes in exothermic reactions?
Exothermic reactions typically form stronger bonds in products than those in reactants.
What is the key difference in energy changes between exothermic and endothermic reactions?
Exothermic reactions release energy, while endothermic reactions absorb energy.
Multiple Choice: Which of the following is an example of an exothermic process? A) Photosynthesis B) Combustion C) Melting ice
B) Combustion
Multiple Choice: Which of the following processes is endothermic? A) Dissolving salt in water B) Burning wood C) Respiration
A) Dissolving salt in water
What is the unit commonly used to measure enthalpy changes?
Kilojoules per mole (kJ/mol)
What is the definition of a fuel?
A substance that provides energy through combustion or chemical reaction.
Distinction between fossil fuels (coal, natural gas, petrol) and biofuels (biogas, bioethanol, biodiesel) based on renewability.
List the types of fossil fuels.
- Coal
- Natural gas
- Petrol
Fossil fuels are non-renewable resources formed from the remains of ancient organisms.
List the types of biofuels.
- Biogas
- Bioethanol
- Biodiesel
Biofuels are renewable resources produced from biological materials.
What is renewability?
The ability of a resource to be replaced by natural processes within a relatively short period of time.
This concept is critical in distinguishing between fossil fuels and biofuels.
What are the fuel sources for the body measured in kJ g-1?
- Carbohydrates
- Proteins
- Lipids (fats and oils)
These macronutrients provide energy for bodily functions.
What is photosynthesis?
The process that converts light energy into chemical energy, producing glucose and oxygen.
The equation is: 6CO2(g) + 6H2O(l) → C6H12O6(aq) + 6O2(g).
What is the balanced equation for cellular respiration?
C6H12O6(aq) + 6O2(g) → 6CO2(g) + 6H2O(l)
This process involves the oxidation of glucose as a primary energy source.
What is the process for the production of bioethanol?
Fermentation of glucose followed by distillation.
The equation is: C6H12O6(aq) → 2C2H5OH(l) + 2CO2(g).
What are exothermic reactions?
Reactions that release energy, typically characterized by bond making.
They are contrasted with endothermic reactions, which absorb energy.
What are endothermic reactions?
Reactions that absorb energy, characterized by bond breaking.
Enthalpy changes (∆H) are measured in kJ.
What units are used to measure enthalpy changes?
Measured in kJ, molar enthalpy changes in kJ mol-1, and enthalpy changes for mixtures in kJ g-1.
These measurements are crucial for understanding energy changes in chemical reactions.
What is the significance of energy profile diagrams?
They represent the energy changes during chemical reactions, including activation energy and enthalpy changes.
Useful for visualizing exothermic and endothermic reactions.
How do you determine limiting reactants in chemical reactions?
By calculating the amount of reactants consumed and identifying which one runs out first.
Limiting reactants dictate the maximum amount of product formed.
What are combustion reactions?
Exothermic reactions involving the reaction of fuels with oxygen, resulting in the release of energy.
Includes complete and incomplete combustion.
What is the difference between complete and incomplete combustion?
Complete combustion produces carbon dioxide and water, while incomplete combustion produces carbon monoxide and/or soot.
Balanced thermochemical equations are used to represent both types.
Fill in the blank: The balanced equation for the complete combustion of organic molecules includes _______.
[Balanced thermochemical equations]
These equations include states and are derived from experimental data.
