Chemical Reactions Quiz Preparation

1

Chemical Reactions rearrange atoms to form new molecules.

2

No atoms (lego) are created or destroyed, they only get rearranged.

Chemical Reactions rearrange atoms to form new molecules.

Reactants: the molecules you began with. (the molecules that reacted together)

Products: the molecules you end up with. (the molecules that are produced)

reactants products3

Law of conservation of matter: Atoms are never created or destroyed in chemical reactions. (they just get rearranged into new molecules).

4

IOW: (in other words) The number of atoms on the products side of a reactions will be exactly the same as the number of atoms found on the reactants side of the reaction.

C O O + H H O H H C O O

6 atoms(the Reactant side)

This reaction has obeyed the Law of Conservation of matter. LOCOM

5

Carbon dioxide Water Carbonic Acid CO2 + H2O H2CO3

----------Reactants---------------- ---Products---

6 atoms (product side)

All the equations we use will be correctly balanced and obey the LOCOMO2 + 2H2 H2O + H2O

6

OO + HH HH HHO HHO

These small numbers represent the number of atoms in the molecule.

These large numbers represent the number of molecules on this side of the reaction.

Rewritten to show all atoms

O2 + H2 + H2 H2O + H2O

Rewritten to show all atoms: OO + HH HH HHO HHO

7

O2 + 2H2 2H2O1 oxygenmolecule

2 Hydrogen molecules

2 watermolecules

Rewritten to show all molecules separately:

2C2H6 + 7O2 4CO2 + 6H2O

Did this reaction obey the LOCOM ?

Yes it did, since it is the atoms (not the molecules) that must be the same on both sides.

8

How many reactant molecules are there? 9 molecules How many product molecules

are there? 10 molecules

2C2H6 + 7O2 4CO2 + 6H2ORewritten to show all molecules:

C2H6 C2H6 + O2 O2 O2 O2 O2 O2 O2

CO2 CO2 CO2 CO2 + H2O H2O H2O H2O H2O H2ORewritten to show all atoms: CCHHHHHH CCHHHHHH + OO OO OO OO OO OO OO

COO COO COO COO + HHO HHO HHO HHO HHO HHO

9

6CO2 + 6H2O C6H12O6 + 6O2How many reactant molecules? How many product molecules?

12 molecules 7 molecules

Rewritten to show all molecules:

CO2 CO2 CO2 CO2 CO2 CO2 + H2O H2O H2O H2O H2O

H2O C6H12O6 + O2 O2 O2 O2 O2

O2

Rewritten to show all atoms: COO COO COO COO COO COO + HHO HHO HHO HHO HHO HHO

CCCCCCHHHHHHHHHHHHOOOOOO + OO OO OO OO OO OOThe same number of atoms are always on both sides = LOCOM

10

Chemical equations handout.

And then the chemical equations QUIZ.

11

12

13

3

1

14

2

15

6

16

6

17

18

16 1

1

18

36

1616

1

1

1

1

19

Now try part 2

20

7

21

6

22

18

C C H HC C H H

O OO OO OO OO O

C O OC O OC O OC O O

H H OH H O

23

18

C C H HC C H H

O OO OO OO OO O

C O OC O OC O OC O O

H H OH H O

24

26

C C H HC C H H

O OO OO OO OO O

C O OC O OC O OC O O

H H OH H O

12 12 1 1

25

44

C C H HC C H H

O OO OO OO OO O

C O OC O OC O OC O O

H H OH H O

12 16 16

26

212

C C H HC C H H

O OO OO OO OO O

C O OC O OC O OC O O

H H OH H O

12 12 1 1

12 16 16

12 16 16

12 16 16

12 16 16

1 1 16

1 1 16

27

212

C C H HC C H H

O OO OO OO OO O

C O OC O OC O OC O O

H H OH H O

12 12 1 1

12 12 1 1 16 1616 16

16 16

16 16

16 16

28

atoms moleculemolecules reaction

29

One last chance to

review

30

2C2H6 + 7O2 4CO2 + 6H2O

How many product molecules are there?

ethane oxygen carbon dioxide water

31

2C2H6 + 7O2 4CO2 + 6H2O

How many product molecules are there?

10

ethane oxygen carbon dioxide water

32

2C2H6 + 7O2 4CO2 + 6H2O

How many reactant atoms are there?

ethane oxygen carbon dioxide water

33

2C2H6 + 7O2 4CO2 + 6H2O

How many reactant atoms are there?

30

ethane oxygen carbon dioxide water

CCHHHHHHCCHHHHHH

OOOOOOOOOOOOOO

Each letter is an atom.

34

2C2H6 + 7O2 4CO2 + 6H2O

How many oxygen atoms are in the products?

ethane oxygen carbon dioxide water

35

2C2H6 + 7O2 4CO2 + 6H2O

How many oxygen atoms are in the products?

14

ethane oxygen carbon dioxide water

COOCOOCOOCOOHHOHHOHHOHHOHHOHHO

Only count the “O” (oxygen) atoms

36

2C2H6 + 7O2 4CO2 + 6H2O

What is the mass of 1 ethane molecule?

ethane oxygen carbon dioxide water

37

2C2H6 + 7O2 4CO2 + 6H2O

What is the mass of 1 ethane molecule?

30

ethane oxygen carbon dioxide water

C C H H H H H H12 +12 + 1 + 1 + 1 + 1 + 1 + 1 = 30

38

2C2H6 + 7O2 4CO2 + 6H2O

What is the mass of all the ethane?

ethane oxygen carbon dioxide water

39

2C2H6 + 7O2 4CO2 + 6H2O

What is the mass of all the ethane?

= 30

ethane oxygen carbon dioxide water

C C H H H H H H12 12 1 1 1 1 1 1

= 30C C H H H H H H12 12 1 1 1 1 1 1

Total = 60

40

2C2H6 + 7O2 4CO2 + 6H2O

What is the mass of all the products?

ethane oxygen carbon dioxide water

41

2C2H6 + 7O2 4CO2 + 6H2O

What is the mass of all the products?

284

ethane oxygen carbon dioxide water

COOCOOCOOCOOHHOHHOHHOHHOHHOHHO

12+16+16

12+16+16

12+16+16

12+16+16

1+1+16

1+1+16

1+1+16

1+1+16

1+1+16

1+1+16

42

Now you can go and retake the quiz

with Mr. Gillam during lunch.