chap3, form 5

Question 1

definition of thermochemistry

Answer 1

heat change in a reaction either released or absorbed during a chemical reaction

Question 2

WHAT ARE THE 2 TYPES OF HEAT CHANGE IN REACTION (so aggressive lol)

Answer 2

exothermic

endothermic

Question 3

definition of exothermic

Answer 3

heat released to surrounding in the chemical reaction

Question 4

gimme 3 examples of exothermic reaction

Answer 4

respiration
oxidation of metal
neutralisation

Question 5

chemical eq of respiration bitch

Answer 5

C6H12O6 + 6O2 –> 6CO2 + 6H2O + heat e

Question 6

chemical eq of oxidation of metal (Na)

Answer 6

4Na + O2 –> 2Na2O

Question 7

chemical eq of neutralisation

Answer 7

HCl + KOH –> KCl + H2O

Question 8

ΔH of exothermic is__

Answer 8

negative

Question 9

energy change during exothermic reaction

Answer 9

chemical e –> heat e

Question 10

definition of endothermic

Answer 10

heat absorbed from surrounding from the chemical reaction

Question 11

gimme 3 examples of endothermic reaction

Answer 11

photosynthesis
decomposition of metal carbonate
decomposition of metal nitrate

Question 12

chemical eq of photosynthesis

Answer 12

6CO2 + 6H2O –> (light on arrow) 6O2 + 6CH12O6

Question 13

chemical eq of decomposition of metal carbonate

Answer 13

2CuCO3 –> Cu + CO2

Question 14

chemical eq of decomposition of metal nitrate

Answer 14

2Mg(NO3)2 –> 2MgO + 4NO +O2

Question 15

ΔH of endothermic is__

Answer 15

positive

Question 16

energy change during endothermic reaction

Answer 16

heat e –> chemical e

Question 17

definition of energy level diagram

Answer 17

a diagram to show energy level(heat energy content) between the reactants and the product

Question 18

definition of heat of reaction, ΔH

Answer 18

heat is absorbed or released during a chemical reaction

Question 19

unit of ΔH

Answer 19

kJ/mol

Question 20

formula to find ΔH

Answer 20

Hproduct - Hreactant

Question 21

describe shape of energy level diagram

Answer 21

straight mfs

Question 22

energy level diagram: during endothermic reaction, temperature of mixture __
the total energy content of ____ is_____than “” of ____ ΔH is ___

Answer 22

decrease
product
higher 
reactants
positive

Question 23

energy level diagram: during exothermic reaction, temperature of mixture __
the total energy content of ____ is higher than “” of ____ ΔH is ___

Answer 23

increase
product 
lower
reactants
negative

Question 24

describe shape of energy profile diagram

Answer 24

curvy good soup

Question 25

energy profile diagram: in endothermic reaction. heat energy ___ to ___ the ____ in _1_ _2_ than heat energy ____ during ____ of bonds in ___

Answer 25

``` absorbed break bonds reactants greater released formation products ```

Question 26

energy profile diagram: in exothermic reaction. heat energy during ___ of ___ in _1_ _2_ than heat energy ____to ____ the bonds in ___

Answer 26

``` released formation bonds products greater absorbed break reactants ```

Question 27

definition of activation energy

Answer 27

minimum energy needed to enable chemical reaction to happen

Question 28

what are the 4 types of heat of reactions, ΔH

Answer 28

``` heat of: precipitation displacement neutralisation combustion ```

Question 29

formula to find heat change/released, Q

Answer 29

Q = mcθ

Question 30

what is density of aqueous solution and water?

Answer 30

1 g/cm3

Question 31

what is value of specific heat capacity, c

Answer 31

4.2 J g-1 C-1

Question 32

is heat lost to surrounding during reaction?

Answer 32

no

Question 33

will any heat be absorbed by apparatus (thermometer)?

Answer 33

no

Question 34

formula to find mole of solution

Answer 34

mol = mV/1000

Question 35

formula to find mole of solid

Answer 35

mol = mass/molar mass

Question 36

1 kJ/mol equal to __

Answer 36

1000 J/mol

Question 37

definition of heat of precipitation

Answer 37

heat change when 1 mole of precipitate is formed from their Ions in an aqueous solution

Question 38

thermochemical eq of heat of precipitation

Answer 38

cation + anion --> insoluble salt, then state ΔH+/-

Question 39

unit for Q is __

Answer 39

Joule, J

Question 40

unit for heat of reaction, ΔH

Answer 40

kJ/mol

Question 41

heat of reaction is ___ mol

Answer 41

per/one

Question 42

how to find heat for one mol then convert J to kJ by using mol found?

Answer 42

J/mol then divide by 1000

Question 43

definition of heat of displacement

Answer 43

heat change when 1 mole of metal is displaced from its salt solution by a more electropositive metal

Question 44

how many thermochemical eq for heat of displacement ?

Answer 44

2

Question 45

name the 2 thermochemical eq for heat of displacement? | eg Fe react with CuSO4

Answer 45

Fe(s) + CuSO4(aq) + Cu(s) --> FeSO4(aq) + Cu(s), ΔH +/- Fe(s) + Cu2+(aq) --> Fe2+(aq) + Cu(s), ΔH +/-

Question 46

definition of heat of neutralisation

Answer 46

heat change when 1 mole of water is formed from the reaction between an acid an alkali

Question 47

thermochemical eq for heat of neutralisation bestie | eg NaOH react with HCl

Answer 47

NaOH(aq) + HCl(aq) --> NaCl(aq) + H2O(l), ΔH = -57 kJ/mol

Question 48

how many values of neutralisation reactions kena ingat?

Answer 48

4

Question 49

Strong Acid + Strong Alkali

Answer 49

-57 kJ/mol

Question 50

Weak Acid + Strong Alkali

Answer 50

-55 kJ/mol

Question 51

Strong Acid + Weak Alkali

Answer 51

-52 kJ/mol

Question 52

Weak Acid + Weak Alkali

Answer 52

-50 kJ/mol

Question 53

definition of heat of combustion

Answer 53

heat released when 1 mole of substance is completely burnt in excess oxygen, O2

Question 54

why is the value of heat of combustion always -ve?

Answer 54

it is an exothermic reaction

Question 55

thermochemical eq of heat of combustion | eg CH4 react with O2

Answer 55

CH4 + 2O2 --> CO2 + 2H2O, ΔH +/-

Question 56

definition of fuel value

Answer 56

the amount of heat energy released when one gram fuel is completely burnt in excess oxygen, O2

Question 57

unit of fuel value

Answer 57

kJ/g

Question 58

formula to find fuel value

Answer 58

heat combustion of substance (kJ./mol) over molar mass of substance

Question 59

heat combustion is _____to no of carbons in a compound

Answer 59

directly proportional

Question 60

so like if no of carbon ____, the heat released _____

Answer 60

increases | increases

Question 61

application of exothermic reactions in daily life. gimme 3 and like explain shit

Answer 61

hot can: hot food prepared w/out external heat termite reaction: welding of railway tracks combustion of fuel: used for cooking food

Question 62

application of endothermic reactions in daily life. gimme 3 and like explain shit

Answer 62

gel pads: relieve fever by absorbing heat from body self cooling beverages: drinks in cold cans, kept cool with tin acting as insulator to not absorb external heat sorbet: tongue feels cool when sorbet is put in moth

Question 63

what are the 4 factors to consider when choosing fuel

Answer 63

cost, environmental effect, fuel value, availability

Question 64

What is the most suitable fuel to replace petrol in vehicles and why? give like 3 reasons.

Answer 64

Ethanol. As it doesn’t produce soot, it is environmentally friendly. Secondly, it is flammable thus burns easily. Thirdly, it burns with blue flame, meaning lots of heat energy is produced.

Question 65

Which is not the most suitable fuel to be used in vehicles? Why? 2 points and elaborate.

Answer 65

Hydrogen gas. It is an explosive gas. If not handled properly it will cause an explosion. The procedure to prepare hydrogen gas is expensive, which is fractional distillation.