3.3 Energy Calculations Flashcards
Energy released (J)=
Mass of water (g) x specific heat capacity of water x change in temperature (^oc)
Q= m x c x /(delta)T
What is ‘specific heat capacity of water’?
Energy taken to heat 1 gram of water.
A constant c= 4.18 J/g ^oC
Calorimetry
Calculating the energy transferred to the water, if we know the mass of the water and the change in temperature.
What does Hydrogen produce once burnt
Water
Where does the dependent variable go on a graph?
It is the one you measure so goes on Y axis
Exothermic reaction transfers energy…
To the surroundings (so temperature in a reaction rises as energy released, heats up surroundings and so heats solution.)
An endothermic reaction takes in energy…
From the surroundings. ( so temperature in a reaction reduces, energy absorbed, surroundings cool, so reaction mixture/solution cools.)
What type of reaction is photosynthesis?
Endothermic
Once reaction has finished what happens to the solution?
It acclimatises to room temperature as reactants have completely been used up.
BIN MIX
Breaking
Is
eNdothermic
Making
Is
eXothermic
Energy level diagrams show…
The relative energy levels of the reactants and the products of a reaction.
Activation energy
The minimum amount of energy needed to allow a chemical reaction to occur.
Catalyst
Usually a metal used to speed up processes and reactions without actually being used up. It does this by lowering the activation energy needed ( so more particles have the minimum energy required to react.)Provides an alternative pathway for the reaction to take.
Bond energy
The energy required to break a given bond between two atoms.
