1What is a fuel?
Any substance that can release stored energy, usually through combustion.
2What is the difference between renewable and non-renewable fuels?
Renewable fuels can be replenished by natural processes in a short period, while non-renewable fuels are used faster than they are replenished.
3What is a fossil fuel?
A fuel made from the remains of dead organisms after millions of years.
4What is natural gas mostly composed of?
90% methane.
5What is crude oil?
A mixture of different alkanes.
6How are fractions separated in crude oil?
Through fractional distillation.
7What is petrol mostly composed of?
Octane.
8Which type of coal is the most energy-dense?
Black coal.
9What are biofuels?
Fuels derived from biological sources, such as plants and animal waste.
10How is bioethanol produced?
By fermenting glucose from plants using enzymes and microorganisms.
11What is biogas composed of?
60% methane.
12How is biodiesel made?
From vegetable oils or animal fats through transesterification.
13What is the main energy source for humans?
Glucose.
14How is glucose produced?
Through photosynthesis.
15What type of reaction is photosynthesis?
An endothermic reaction.
16What is the opposite reaction of photosynthesis?
Cellular respiration.
17What elements do carbohydrates contain?
Carbon (C), Hydrogen (H), and Oxygen (O).
18What are the main types of carbohydrates?
Glucose, starch, and glycogen.
19What is the main fat used for energy storage?
Triglycerides.
20What elements do proteins contain in addition to C, H, and O?
Nitrogen (N), Phosphorus (P), and Sulfur (S).
21How is bioethanol separated from water after fermentation?
By distillation.
22What is an exothermic reaction?
A reaction that releases energy.
23What is an endothermic reaction?
A reaction that absorbs energy.
24What is enthalpy?
The chemical energy that can be converted to heat (symbol: H).
25What happens when bonds are broken?
Energy is absorbed.
26What happens when bonds are created?
Energy is released.
27What is activation energy (Ea)?
The energy barrier that must be overcome for a reaction to start.
28How does enthalpy change in exothermic reactions?
The enthalpy of products is lower than the reactants (ΔH is negative).
29How does enthalpy change in endothermic reactions?
The enthalpy of products is greater than the reactants (ΔH is positive).
30What is combustion?
A reaction where a substance reacts with oxygen and releases energy.
31What are the products of complete combustion?
Carbon dioxide (CO2) and water (H2O).
32What are the possible products of incomplete combustion?
Carbon monoxide (CO) and soot (C).
33What is heat of combustion?
The energy released when a fuel is completely combusted.
34In what units is heat of combustion measured?
kJ for mixtures and kJ/mol for pure fuels.
35What does a thermochemical equation include?
A balanced chemical equation with ΔH (enthalpy change).
36How does ΔH change when a reaction is reversed?
The magnitude stays the same, but the sign changes.
37What happens when the state of matter changes?
Energy is absorbed or released, affecting enthalpy.
38What is the formula for stoichiometry calculations?
n(unknown)/n(known) = coeff.(unknown)/coeff.(known).
39What are greenhouse gases?
Gases that absorb infrared radiation and contribute to the greenhouse effect.
40What are examples of greenhouse gases?
CO2, H2O, CH4.
41What is a limiting reactant?
The reactant that is fully used up in a chemical reaction.
42What is an excess reactant?
The reactant that is left over after the reaction.
43How do you determine the limiting reactant?
Compare mole ratios of reactants to their equation coefficients.
44What is specific heat capacity?
The energy required to increase the temperature of 1g of a substance by 1 K.
45What is the formula for heat energy?
q = mcΔT.
46What is calorimetry?
The measurement of energy released from a reaction in a well-insulated container.
47What is a calibration factor in calorimetry?
The energy required to change the temperature of the calorimeter by 1°C.
48What is the formula for calibration factor?
Calibration factor (J/°C) = E/ΔT = VIT/ΔT.
49How is efficiency calculated?
Efficiency = (useful energy output / energy input) * 100.