Chapter C7- Energy Changes Flashcards
What cannot happen to energy in a chemical reaction?
What do endothermic reactions do?
What do exothermic reactions do?
What are exothermic reactions?
What happens to the energy of the reaction in exothermic?
What happens to the temperature of the surroundings in exothermic?
What are endothermic reactions?
What happens to the energy of the reaction in endothermic?
What happens to the temperature of the surroundings in endothermic?
Energy cannot be created or destroyed
Make things feel cool
Make things feel hot
Reactions that give out energy from the reacting chemicals to the surroundings
It goes down
It goes up
Reactions that take in energy from the surroundings to the reacting chemicals
It goes up
It goes down.
What does an energy profile diagram show for an exothermic reaction?
What are three examples of reactions that are exothermic?
What does an energy profile diagram show for an endothermic reaction?
What are two examples of reactions that are endothermic?
What are the chemical symbols and ionic formulas for the following:
Ammonium
Nitrate
Sulphate
Hydroxide
Carbonate
Shows the reactants going down to the products
Neutralisation, respiration and combustion
Shows the reactants going up to the products
Thermal decomposition and photosynthesis
NH4 +
NO3 -
SO4 2-
OH -
CO3 2-
What are two devices that are exothermic?
What is an example of a device that is endothermic?
What is involved whenever a reaction takes place?
What happens in endothermic reactions concerning bonds?
What happens in exothermic reactions concerning bonds?
What does Ea stand for in an energy profile diagram?
What is this?
What does TriangleH stand for in an energy profile diagram between the reactants and the products?
How is energy represented for TriangleH in an energy profile diagram?
What does the + mean and why?
What does the - mean and why?
Self- heating cans and hand warmers
Chemical cold packs
Energy
Bonds need energy to break
Bonds give out energy when they are made
The activation energy
The minimum energy needed to start a reaction
Change in energy
+/- x amount kJ/mol
Endothermic (energy is required)
Exothermic (energy is given out).
In an exothermic reaction, what is greater to what?
In an endothermic reaction, what is less than to what?
What do batteries rely on?
What are spectator ions?
In a zinc/copper cell:
What do zinc atoms do concerning electrons and so what do they act as?
What do copper ions do concerning electrons and so what do they act as?
What makes a metal atom more reactive?
The energy released when new bonds are formed is greater that the energy absorbed when bonds are broken
The energy released when new bonds are formed is less than the energy absorbed when bonds are broken.
The differing reactivity’s of metals
Ions that remain unchanged on both sides of an equation
Zinc atoms donate electrons and so act as the negative terminal
Copper ions accept electrons and so act as the positive terminal
The greater the tendency for a metal atom to give away electrons to become a positive ion.
What does the greater the difference in reactivity between the two metals used mean?
What are batteries known as and what cannot happen to them?
What can happen to rechargeable cells and how can this happen?
What are fuel cells fed with?
What does this produce?
Where is most of the energy released in a hydrogen fuel cell transferred to?
But what is needed for this to happen?
What happens to the hydrogen gas and so what does it provide a source of?
What is the only waste product produced?
The higher the voltage produced
Batteries are known as a primary cell and cannot be recharged
They can be connected to a power supply that reverses the reactions and regenerates the original reactants
Hydrogen and oxygen
Water
It’s transferred to electrical energy
A constant supply of hydrogen is needed
It’s oxidised and provides a source of electrons
Water.
