3.4 Notes

Question 1

Clues to a chemical reaction

Answer 1

Gas formation
Solid formation( percipitate)
Energy change
Color and or smell change

Question 2

Percipitate

Answer 2

When two liquid substances combine and make a cloudy substance

Question 3

Chemical formula

Answer 3

Abbreviation that uses chemical symbols and numbers to represent a substance. Shows he many of each atom are present in a molecule of a substance

Question 4

Subscript

Answer 4

Number written below and to the right if a chemicals symbol. A subscript can’t be hanged in a chemical formula

Question 5

Can the subscript in a chemical formula change

Answer 5

No

Question 6

Do chemical changes always involve a chemical reaction

Answer 6

Yes

Question 7

Can physical changes have a chemical reaction

Answer 7

They can but not always

Question 8

Examples of physical changes

Answer 8

Melting butter, boiling water, jello melting

Question 9

Examples of chemical changes

Answer 9

Baking cupcakes
Flame
Burnt popcorn

Question 10

Chemical reaction

Answer 10

Process by which one or more substances change to produce one or more different chemical and physical properties

Question 11

Chemical formula

Answer 11

Shows how many of each know no of atom are present in a molecule of the substance

Question 12

Subscript can’t be…..

Answer 12

Changed in a chemical formula. Don’t touch the subscript

Question 13

What are subscripts

Answer 13

Number of atoms in each element of a molecule

Question 14

What is the chemical names for the following covalent compounds
Co2
N2O

Answer 14

Carbon dioxide

Dinitride monoxide

Question 15

Covalent and ionic: share or transfer

Answer 15

Covalent: share
Ionic: transfer

Question 16

Covalent prefixes

Answer 16

Mono, di, tri, penta, hexa, hepta, octa, nona, deca, undeca, dodeca

Question 17

Atoms are never ______ or ___________ in a chemical reaction

Answer 17

Lost or gained

Question 18

Starting and ending substance

Answer 18

Starting: reactant
Ending: product

Question 19

When balancing equations, what should always equal each other

Answer 19

Number of atoms in reactants= number of atoms in the products

Question 20

Coefficient

Answer 20

Tells you how many molecules are needed

Question 21

Remember how to do balancing equations

Answer 21

….

Question 22

Conservation of mass

Answer 22

Mass is neither created or destroyed. Has to be balanced in both sides of the equation

Question 23

Law of conservation energy

Answer 23

Energy can’t be created or destroyed. Energy can be given off

Question 24

Activation energy

Answer 24

Energy is needed for a reaction to occur

Question 25

Examples of activation energy

Answer 25

Friction of a match allowing it to start burning

Question 26

Exothermic reactions and example

Answer 26

Energy is given off
Ex: 2Na+Cl2–>2NaCl+energy
Energy is written in product

Question 27

Know how to draw exothermic and endothermic reactions

Answer 27

…

Question 28

Endothermic reaction and example

Answer 28

Energy is absorbed
Ex:2H2O+ energy–> 2H2+O2
Energy is written in reactant side

Question 29

Common exothermic and endothermic reactions examples

Answer 29

Exothermic:cellular respiration
Endothermic: photosynthesis

Question 30

4 factors that affect chemical reaction rate and example

Answer 30

Temp: high temp=faster rate; low temp=slower rate
Surface area:greater surface area=faster rate; smaller area=slower rate
Concentration: high con= faster rate; low con= low rate
Catalysts and inhibitors: catalyst lowers activation energy needed so rate of reaction is faster; inhibitor slows down or stops reaction

Question 31

Catalyst vs inhibitors

Answer 31

Catalyst: increases rate of reaction
Inhibitor: slows down or stops reaction