Chemical Reactions

Question 1

physical change

Answer 1

change in appearance smell etc. change which does not result in a change in a chemical make up

Question 2

chemical change

Answer 2

change that results in a change in a chemical make up or formula of starting chemicals

Question 3

chemical reaction

Answer 3

process where original substances change into new substances with new properties

Question 4

reactants

Answer 4

original substances or inputs of chemical reactions

Question 5

products

Answer 5

new created substances or outputs of chemical reactions

Question 6

CLUES that a chemical reaction has taken place

Answer 6

1. gas is released 2. color change 3. heat change 4. precipitate formed

Question 7

precipatate

Answer 7

a solid that is formed which cannot stay dissolved in a liquid.

Question 8

ice cream melting example of

Answer 8

physical change

Question 9

boiling water example of

Answer 9

physical change

Question 10

dissolving something example of

Answer 10

physical change

Question 11

biting a candy bar in 1/2 example of

Answer 11

physical change

Question 12

burning leaves

Answer 12

chemical change

Question 13

foods in stomach digesting

Answer 13

chemical change

Question 14

Mix a solid with a liquid, solid disappears while temperature of liquid increases

Answer 14

it cannot be determined if a chemical reaction has taken place or not.

Question 15

are new atoms formed in a chemical reaction

Answer 15

NO

Question 16

chemical equations are used to represent the

Answer 16

reactants and products of a chemical reaction usually using the chemical formula but can use names too

Question 17

equations are balanced to show

Answer 17

atoms are not created or destroyed in a reaction & that mass is conserved

Question 18

to balance equations we add

Answer 18

coefficients to the front of molecules or atoms until we have an equal amount of each atom (and therefore mass) on both sides of the equation

Question 19

we cannot change the subscripts to balance an equation because

Answer 19

this would change the chemicals that are in the reaction

Question 20

combustion

Answer 20

when all substances in a compound combine with oxygen to form carbon dioxide and water

Question 21

synthesis

Answer 21

2 or more substances combine to form 1 new more complex substance

Question 22

decomposition

Answer 22

1 substance breaks down too form 2 or more simpler substances

Question 23

single replacement

Answer 23

an uncombined element replaces an ion that is part of a composition

Question 24

double replacement

Answer 24

two reactants are compounds- they simply switch like charged ions to form two new substances

Question 25

how to identify a combustion equation

Answer 25

hydrocarbon `

Question 26

acids

Answer 26

compounds that give rise to hydrogen ions when dissolved in water (H) NEGATIVE

Question 27

acids are defined as

Answer 27

proton donors

Question 28

bases

Answer 28

compounds that give rise to hydroxide when dissolved in water POSITIVE

Question 29

bases are defined as

Answer 29

proton acceptors

Question 30

neutralization reaction

Answer 30

a reaction between an acid & base

Question 31

what happens during a neutralization reaction (2)

Answer 31

1. negative ions of acid combine with the positive ions of the base to produce an ionic compound called a salt. 2. the hydrogen ion of the acid and the hydroxide ion of the base combine to form water

Question 32

hydroxide

Answer 32

base

Question 33

hydrogen

Answer 33

acid

Question 34

mass is ____ in a balanced chemical equation

Answer 34

conserved

Question 35

new chemicals are ____

Answer 35

created in a chemical reaction

Question 36

the mass is always the

Answer 36

same

Question 37

when determining how many atoms are present..

Answer 37

always distribute to everything even if there are no parentheses

Question 38

fireworks are an example of

Answer 38

chemical change

Question 39

the products of a combustion reaction always are

Answer 39

carbon dioxide and water

Question 40

if the chemical formula is made up of one element

Answer 40

ion

Question 41

if chemical formula is made up of more than 2 elements

Answer 41

there is a polyatomic ion involved in the formula

Question 42

reaction rate

Answer 42

the rate at which reactants change to produce over time ; various things can be done to affect the reaction rate by affecting how quickly the reactant molecules come into contact with each other

Question 43

concentration

Answer 43

the measure of the amount of a substance in a given unit of volume

Question 44

higher concentrated chemicals will proceed at

Answer 44

a faster rate because there are more chances for reacting particles to come in contact

Question 45

surface area

Answer 45

refers to how much of the material is exposed. breaking a solid into smaller particles will increase surface area

Question 46

increased surface area will

Answer 46

increase the rate of reaction because it increases the exposure of reactants to eachother

Question 47

temperature

Answer 47

the measure of energy of the particles

Question 48

increased temperature will

Answer 48

increase the rate of reaction because faster moving reacting particles will come in contact sooner than slower moving particles

Question 49

catalyst

Answer 49

a substance that increases the rate of reaction but itself is not changed by the reaction. it can be recovered after the reaction is over

Question 50

a catalyst will

Answer 50

increase the rate of reaction by lowering the energy needed to allow the reaction to occur

Question 51

stirring

Answer 51

A mixing of reactants

Question 52

stirring will

Answer 52

increase the rate of reactants by increasing the exposure of reactions to one another

Question 53

which law is violated when we don't balance equations

Answer 53

the law of conservation of mass

Question 54

grinding pepper

Answer 54

physical change

Question 55

melting wax

Answer 55

Physical

Question 56

During a chemical equation, whats taking place at the atomic level

Answer 56

the atoms of reactant chemicals rearrange to create different product chemicals

Question 57

KNO2 is a

Answer 57

salt

Question 58

HCN is a

Answer 58

acid

Question 59

Fe(OH)2 is a

Answer 59

base

Question 60

general products made when an acid and base are combined

Answer 60

a salt and water

Question 61

Diatomic molecules always get a

Answer 61

2 subscript

Question 62

formula for combustion

Answer 62

CO2 +H2O