P1: Energy Changes Flashcards
Give some examples of exothermic reactions.
Combustion reactions, many oxidation reactions and most neutralisation reactions.
What is the name of the reaction where energy is transferred to the surroundings?
Exothermic,
What is the name of the reaction where energy is taken in from the surroundings?
Endothermic.
In an exothermic reaction, what has more energy: reactants or products?
Reactants, because energy is RELEASED.
In an endothermic reaction, what has more energy: the reactants or the products?
The products, because energy is ABSORBED.
In an exothermic reaction, what is the overall energy change?
Negative.
In an endothermic reaction, what is the overall energy change?
Positive.
An in endothermic reaction, are bonds broken or formed?
Broken.
In an exothermic reaction, are bonds broken or formed?
Formed.
When you break bonds, is energy taken in or given out?
Taken in.
When you form bonds, is energy taken in or given out?
Given out.
How can a simple cell be made?
By connecting two different metals in contact with an electrolyte.
In a non-rechargeable cell, how long is a voltage produced?
Until one of the reactants is used up.
What two things guarantee that fuel cells will produce a voltage?
If they have:
-A constant supply of a suitable fuel
-Oxygen
What are the products of hydrogen-oxygen fuel cells?
Water vapour.
What are the pros of alkaline cells?
Cheaper to manufacture.
What is the con of an alkaline cell?
May end up in landfill sites once fully discharged; recyclable though it is expensive
What is a pro of a rechargeable cell?
Can be recharged many times before being recycled, reducing the use of resources
What is a con of a rechargeable cell?
Costs more to manufacture
What are the pros of a hydrogen fuel cell?
Easy to maintain as there are no moving parts; small size; water is the only chemical product
What are the cons of hydrogen fuel cells?
Very expensive to manufacture; need a constant supply of hydrogen fuel, which is a flammable gas
What type of reaction is Sodium Hydrogencarbonate with Nitric Acid?
Endothermic.
Is thermal decomposition endothermic or exothermic?
Endothermic.
