C7 Energy changes

Question 1

whats an exothermic reaction

Answer 1

a reaction that releases energy to the surroundings

Question 2

whats an endothermic reaction

Answer 2

a reaction that takes energy out of the surroundings

Question 3

whats higher in an exothermic reaction energy needed to break bonds or the energy released in making new bonds

Answer 3

more energy is released from making new bonds

Question 4

whats higher in an endothermic reaction energy needed to break bonds or the energy released in making new bonds

Answer 4

more energy is needed to break bonds

Question 5

what’s a use for exothermic changes

Answer 5

hand warmers and self-heating cans

Question 6

what’s a use for endothermic changes

Answer 6

instant cold packs

Question 7

how can you make a simple electric cell

Answer 7

join 2 metals by a wire and place them into a salt solution.
the more reactive meta will donate electrons to the less reactive one

Question 8

how can you increase a homemade simple cells voltage

Answer 8

use metals with a greater difference in reactivity
(instead of sodium and lithium use lithium and potassium)

Question 9

what are the advantages of hydrogen fuel cells

Answer 9

don’t need to be electrically recharged
no pollutants produced
can be a range of sizes for different uses

Question 10

what are the disadvantages of hydrogen fuel cells

Answer 10

hydrogen is highly flammable
hydrogen is sometimes produces for the cell by non-renewable sources
hydrogen is difficult to store

Question 11

what are the products of a hydrogen fuel cell

Answer 11

water