unit 5 + 2 - energy + bonding
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Take in energy? (what reaction type)
Endothermic
Gives out energy (what reaction type)
exothermic
Increase in temp in surrounding/environment ((what reaction type)
exothermic
Decrease in temp in surrounding/environment (what reaction type)
endothermic
Heat is transferred from an object at high temp to a lower temp object until both of them are ……
equal in temp
Bond breaking what type of reaction
Endothermic - absorbs energy
Bond forming what reaction type
exothermic - releases energy
Enthalpy
Change in Temp
How to calculate change in enthalpy using graph and using bond enthalpy calculations
From graph you do: product energy - reactant energy From bond enthalpy calculations you do: reactants energy - products energy
Bond Enthalpy
This is the energy required to break one mole of a specific bond type
If heat is absorbed (endothermic) ΔH is
positive
If heat is released (exothermic) ΔH is
negative
Entropy
Measurement of a system’s disorder or randomness
Entropy is most and least in
Most in gaseous Least in solids
What all is required for a thing to burn
Heat, oxygen and fuel (substance containing carbon)
In which energy diagram is the product energy, less than the reactant energy
Exothermic (energy released is calculated by product energy - reactant energy)
In which energy diagram is the product energy, more than the reactant energy
Endothermic (Energy absorbed is calculated by product energy - reactant energy)
Products of any combustion reaction
Water vapour and Carbon dioxide
Incomplete combustion
When there is insufficient oxygen in a combustion reaction and instead of carbon dioxide, carbon monoxide is formed
Ignition temp
Min temp required for something to catch fire
specific heat capacity
Amount of heat energy required to change the temperature of 1kg of a substance by 1 degree Celsius
In an endothermic reaction, the energy needed to break existing bonds is ______________ the energy released from forming new bonds.
more than
how does a co2 fire extinguisher work?
CO2 is hevaier tha oxygen and hence this extinguisher forms a cloud of CO2 around the fire, essentially pushing the oxygen away and without it the fire cant burn
Bonding
The force of attraction between atoms so that they can be joined chemically