Chapter 4 Test

Question 1

How is matter described

Answer 1

by its characteristics/properties and how it changes (physical and chemical changes)

Question 2

What is a physical change

Answer 2

any change that alters the form or appearance of a substance without changing it to another substance

Question 3

What is a chemical change

Answer 3

Any change in matter that produces one or more new substances

Question 4

What happens when something undergoes a chemical change

Answer 4

it gains new properties and changes in energy

Question 5

What is a reactant

Answer 5

Substances that undergo the chemical changes

Question 6

What are products

Answer 6

The substances that form from reactants in a chemical change

Question 7

When do atoms form bonds

Answer 7

when they share or transfer electrons

Question 8

What is a precipitate

Answer 8

a solid that forms from liquids during a chemical reaction

Question 9

What 3 ways can you observe a chemical change

Answer 9

precipitate, gas production, and color change

Question 10

What does forming bonds release

Answer 10

energy

Question 11

What is an exothermic reaction

Answer 11

a reaction where the energy released as the products form is greater than the energy required to break the bonds for the reactants

Question 12

What is an endothermic reaction

Answer 12

a reaction where more energy is required to break the bonds of the reactants than is released by the formation of the products

Question 13

What is a chemical equation

Answer 13

a way to show a chemical reaction using symbols instead of words, tells you reactants and products

Question 14

What is a chemical formula

Answer 14

a combination of symbols that represents the elements in a compound (an equation uses several chem formulas)

Question 15

What does the arrow mean in a chem. equation

Answer 15

“yields”

Question 16

What does the plus mean in a chem. equation

Answer 16

“combines(/combined) with”

Question 17

Which French scientist first demonstrated the law of conservation of mass

Answer 17

Antoine Lavoisier

Question 18

What is the law of conservation of mass

Answer 18

during a chemical equation matter is not created or destroyed only rearranged

Question 19

What makes an equation balanced

Answer 19

when the same amout of atoms are present on both sides of an equation

Question 20

When was Antoine Lavoisier killed

Answer 20

The French Revolution

Question 21

What was Antoine Lavoisier other than a scientist

Answer 21

a lawyer and tax collector

Question 22

What happens in an open system

Answer 22

matter can enter from or escape to the surroundings

Question 23

What happens in a closed system

Answer 23

matter doesn’t enter or leave

Question 24

What is used to balance equations

Answer 24

coefficients

Question 25

What is a coefficient

Answer 25

a number placed in front of a chemical formula in an equation that tells you the amount of a reactant or product that takes part in a reaction

Question 26

What are the 3 types of Chemical Reactions

Answer 26

synthesis, decomposition, and (double/single) replacement

Question 27

What is synthesis

Answer 27

when 2 or more elements/compounds combine to make a more complex substance

Question 28

What is decomposition

Answer 28

when compounds break down into simpler products

Question 29

What is replacement

Answer 29

when one element replaces another element in a compound or if 2 elements in a compound trade places

Question 30

When fuel burns to produce CO2 what type of chemical reaction is occuring

Answer 30

a exothermic synthesis chemical reaction

Question 31

What is activation energy

Answer 31

the amount of energy needed to break the chemical bonds of the reactants and then form the new bonds (the minimum amount of energy needed to start a chemical reaction)

Question 32

What do endothermic reactions need that exothermic reactions don't

Answer 32

energy to continue the reaction

Question 33

What do the product in endothermic reactions have

Answer 33

more energy than the reactants

Question 34

What needs to happen for a chemical reaction to happen faster

Answer 34

the particles of the reactants need to collide either quicker or with more energy (they also happen quicker if there is more particles)

Question 35

What factors can affect the rates of reactions

Answer 35

surface area, temperature, concentration, and the presence of catalysts or inhibitors

Question 36

Why does temperature affect the speed of a reaction

Answer 36

because the particles move quicker from thermal energy

Question 37

Why does concentration affect the speed of a reaction

Answer 37

because there are more particles to react

Question 38

What do catalysts do

Answer 38

they lower the amount of activation energy needed for a reaction to start

Question 39

What are enzymes

Answer 39

biological catalysts that help reactions occur at body temperature

Question 40

How do enzymes work

Answer 40

they bring reactant molecules close together

Question 41

What is an inhibitor (aka preservative)

Answer 41

a material used to decrease the rate of a chemical reaction