Chapter 1

Question 1

What is an hypothesis ?

Answer 1

It’s a tentative explanation or prediction in accord with current knowledge

Question 2

In chemistry we use _________ and __________ type of information.

Answer 2

quantitative and qualitative

Question 3

What is quantitative informations ?

Answer 3

numerical data

Question 4

What is qualitative informations ?

Answer 4

non-numerical observations

Question 5

what is a theory ?

Answer 5

It’s a well-tested, unifying principle that explains a body of facts and the laws based on them

Question 6

what are the goals of sciences ? (4 goals)

Answer 6

o prediction
o control
o understanding
o explaining

Question 7

What is a state of matter ?

Answer 7

An easily observed property of matter that is, whether a substance is a solid, liquid or gas.

Question 8

Characteristics of solid (state of matter)

Answer 8

-Particle are packed closely together
-Hard
-Little volume change with changes of temperature

Question 9

Characteristics of liquid (state of matter)

Answer 9

-Particles are arranged randomly
-They are not packed
-They can move past one another

Question 10

Characteristics of gas (state of matter)

Answer 10

-Particles are far apart
-Move extremely rapidly
-Not constrained by their neighbours
-Volume and pressure change dramatically with temperature changes

Question 11

what is the energy of motion?

Answer 11

Kinetic energy

Question 12

The kinetic energy is responsible of…….

Answer 12

The temperature

Question 13

Kinetic energy: In the solid state the particles ….(3 answers)

Answer 13

• are packed closely together
• vibrate around their average position
• Very low compressibility

Question 14

Kinetic energy: In the liquid state the particles ….(4 answers)

Answer 14

• are oriented randomly
• occupy a little more space than the solid state and they keep moving relative to one another
• still stay close to one another
• Very low compressibility

Question 15

Kinetic energy: In the gaseous state the particles ….(3 answers)

Answer 15

• are far apart
• move fast in a linear motion until they collide with another particle when kinetic energy is exchanged and direction of motion changes
• Very high compressibility

Question 16

What is a pure substance ?

Answer 16

• Has a set of unique by which which it can be recognized

- It cannot be separated into 2 or more different species by any physical technique at ordinary temperature

Question 17

What is a mixture?

Answer 17

Consist of 2 or more substances that can be separated by physical technique

Question 18

What is a heterogenous mixture?

Answer 18

Can be detected by the naked eye

Question 19

What is a homogenous mixture?

Answer 19

-2 or more pure substance in the same phase.

-Often called solution

Question 20

What is an element?

Answer 20

substances that are composed of only one type of atom

Question 21

What is a compound?

Answer 21

A compound is 2 or more different element held together by chemical bonds.

Question 22

What are the 2 main differences between an element and a compound?

Answer 22

• A compound has distinctly different characteristics from its parent element. An element is only composed of one type of atom.
• Compound has a definite percentage (%) composition (by mass) of its combining element. An element has 100% composition of his type of atom.

Question 23

What is physical properties?

Answer 23

are properties which can be observed and measured without changing the composition of substances

Question 24

Give at least 4 physical properties. The answer has 10 properties.

Answer 24

o	colour
o	state of matter
o	melting point 
o	boiling point 
o	density 
o	solubility 
o	electric conductivity 
o	malleability 
o	ductility 
o	viscosity

Question 25

What is an extensive property?

Answer 25

depend on the amount of a substance present

ex: the amount of energy transferred as heat from burning gasoline

Question 26

What is an intensive property ?

Answer 26

do not depend on the amount of a substance present

ex: a sample of ice will melt at 0 Celsius, no matter is it has an ice cube or an iceberg

Question 27

the ratio of two extensive properties is …………

Answer 27

an intensive property

Question 28

What is a physical change ?

Answer 28

• the identity of a substance is preserved
• a physical change does not result in a new chemical substance
• the particles (atoms, molecules and ions) present before and after the change are the same

Question 29

What is a chemical change?

Answer 29

• one or more substances (reactants) are transformed into one or more different substance (products)
• the representation of the change using chemical formulas is the chemical equation

Question 30

What is the type of energy associated with motion?

Answer 30

Kinetic energy

Question 31

which type of energy results form an object’s position or state ?

Answer 31

potential energy

Question 32

Acoustic energy is what type of energy?

Answer 32

Kinetic energy

Question 33

Gravitational energy is what type of energy?

Answer 33

Potential

Question 34

Chemical energy is what type of energy?

Answer 34

Potential

Question 35

Mechanical energy is what type of energy?

Answer 35

Kinetic

Question 36

electrical energy is what type of energy?

Answer 36

Kinetic

Question 37

Thermal energy is what type of energy?

Answer 37

Kinetic

Question 38

electrostactical energy is what type of energy?

Answer 38

Potential

Question 39

nuclear energy is what type of energy?

Answer 39

Potential

Question 40

What is the Law of conservation of energy?

Answer 40

Energy can neither be created nor destroyed

Question 41

In a chemical reaction what is the endothermic reaction?

Answer 41

Sum of the bond energy in all REACTANTS +heat ABSORBED=sum of the bond energy in all PRODUCTS

Question 42

In a chemical reaction what the the exothermic reaction?

Answer 42

Sum of the bond energy in all PRODUCTS + heat EMITTED= sum of the bond energy in all REACTANTS