Exothermic and Endothermic Reactions Flashcards
What is an exothermic reaction?
transfers energy to the surroundings, temperature in the surroundings increase
What is an endothermic reaction?
takes in energy from the surrounding, temperature in the surroundings deceases
What is the activation energy?
minimum amount of energy particles must have in order to react
Why do we place the polystyrene cup into a beaker?
stops the cup from falling over
Why is important to repeat experiments?
calculate a mean value
Why is it important to use a polystyrene cup with a lid?
polystyrene is a good thermal insulator so reduces heat loss through the sides of the container and air
What is an electrolyte?
solution that can conduct electricity
Why do cells run out?
chemicals in the cell run out and the reaction stops
Why do Magnesium and copper have a greater potential difference?
they have a greater difference in reactivity
What is a battery?
contains 2 or more cells
Why do alkaline batteries run out?
reactants in the battery run out
Advantages of hydrogen fuel cells?
- produce electricity as long as you provide hydrogen
- do not get less efficient
Disadvantages of rechargeable batteries?
- may run out
- store less electricity the more charging cycles they go through
Disadvantages of hydrogen fuel cells?
- hydrogen is an explosive gas and is very difficult to store safely
- produce a low potential difference
Advantages of rechargeable batteries?
- no dangerous fuel are required
- greater potential difference
