Energy changes (book)

Question 1

what is a system what is a surrounding

Answer 1

the molecule is a system, everything else is the surrounding

Question 2

what is an exothermic reaction and examples

Answer 2

The molecule give out heat energy to the surrounding, The temp of the surrounding increses.
examples: Combustion, hand-warmers, self- heating cans

Question 3

what is an exothermic reaction and examples

Answer 3

The molecules take IN energy from the surrounding , The tempretures of the surround decreases
Examples: Sports injuary pack, thermal decoomposition, photosyntesis.

Question 4

is breaking and making bonds exo or endo?

Answer 4

when chemical bonds are broken you need to take in energy from the surrounding which means it is endothermic

when chemical bonds are made the molecule releases energy into the surrounding which means it is exothermic

Question 5

how to determine if energy is exo or endothermic

Answer 5

calculate if more energy is realeas> energy take = exo
energy taken> energy released = endo

Question 6

what is the activation energy

Answer 6

minimum amount of energy need for reaction to take place

Question 7

what is a total energy change

Answer 7

difference between the energy of the reactant and energy of the product

Question 8

how would the exothermic graph look

Answer 8

the reactant would be higher than the product

Question 9

how would the endothermic graph look

Answer 9

the reactant is lower than the product

Question 10

energy change =

Answer 10

energy taken in - energy given out

Question 11

if the number is negative the reaction is

Answer 11

exothermic

Question 12

describe the steps for the energy changes practical

Answer 12

11.Use the 50cm measuring cylinder to put 30 cm dilute HCl acid into the polyesterene cup.
2. Stand the cup inside the beaker.This will make it more stable
3. Use the thermometer of the acid.Record it in the first blank coloumn of the table such as the one below.
4.Put 5 cm sodium hydroxide solution into the 10 cm measuring cylinder
5.Pour the sodium hydroxide into the cup.Gently stir the solution with the thermometer.
6.When the reaing on the temotheter stops changing, wwrite the tempeture in the next space in the table.
7. Repeat steaps 4 and 5 to addfurther 5 cmamounts of sodium hyroxide to the cup.A total of 40 cm needs to be added.
8.The last few addition should produce a tempreture fall rather than a rise.
9. Repeat stepps 1-6 and record the results in the second blank column of the table
10. Calculate the mean ma temp reached for each of the volumes of sod.