Fuels - ch 1C and D Flashcards
what is energy content
the chemical energy of a substance - high in fuels
amount of heat energy produced upon burning
1 gram of a pure substance
what kind of reaction is used for energy production and how
combustion reactions
reactants combine with oxygen to produce co2 and water. the thermal energy released can be converted into electrical energy
what is meant by metabolism
chemical reactions in the body’s cells that change food into energy
what is glucose and how is it made
an essential molecule - primary source of energy for almost all living organisms
produced through cellular respiration in plants - photosynthesis
what is photosynthesis
Photosynthesis is the process by which plants, algae, and certain bacteria convert
light energy from the sun into chemical energy in the form of organic compounds,
such as glucose
outline the steps of photosynthesis
absorption of light by chlorophyll in the chloroplast
used to split water into hydrogen and oxygen ions
used to build carbs(sugar) from co2 by a series of complex chem reactions
what is cellular respiration
process by which organisms convert glucose into energy.
how do we get energy from food
digestion - polymers in food and broken down into monomers ie glucose
converted into chem energy by oxidation reaction ie cellular respiration
glucose + oxygen = c.dioxide + water + chem energy
photosynthesis and CR both require
water
what are exothermic and endothermic reactions
exothermic release energy
endothermic absorb energy
what is enthalpy change
represents the total change in chemical energy during a reaction.
what unit of measurement is used for
- enthalpy of a substance
- molar enthalpy of a pure sample of a chem compound
- enthalpy of a mixture of chem compounds
kJ
kJ/mol
kJ/g (as molar mass cannot be determined)
what is meant by activation energy
For a reaction
to occur, a minimum initial amount of chemical energy is required to break the
chemical bonds in the reactants
which type of reactions have positive and negative enthalpy and why
exothermic - negative. a lot more energy is released by the creation of bonds as compared to the activation energy.
endothermic - positive - most of the activation energy is retained or absorbed. very little is released after activation
what are the products of incomplete combustion and when does it occur
it occurs when there is a limited supply of oxygen. products involve CO2, CO and solid Carbon aka soot
