Chapter 1 - Matter and Measurement

Question 1

What is Chemistry?

Answer 1

• The scientific study of matter, its properties, its
  interactions with other matter and with energy
• Chemistry comprises everything in the universe
  except for the space in a vacuum

Question 2

What is a law in chemistry?

Answer 2

A law, which has no exceptions, describes some aspect of the natural world

Question 3

What is a theory in chemistry?

Answer 3

Theories explain observations and laws. A theory that is not 100% correct can still be useful

Question 4

What are the three main states of matter?

Answer 4

The three classical states are solid, liquid and gas

Question 5

What are some non-classical states matter can exist in?

Answer 5

Glass, plasma, liquid crystal and supercritical fluids

Question 6

What is a pure substance?

Answer 6

A substance that has constant compositions

Question 7

What is an element?

Answer 7

A substance that cannot be decomposed chemically into simpler substances

Question 8

What is a compound?

Answer 8

A substance that can be broken down into elements

Question 9

What is a homogeneous mixture?

Answer 9

A substance that has a visibly distinguishable parts, also known as a solution

Question 10

What is a heterogeneous mixture?

Answer 10

A substance where you can see the components, which can be separated

Question 11

What is a physical change?

Answer 11

A change in the form of a substance, but not its chemical composition

Question 12

What is a chemical change?

Answer 12

A substance that becomes a new substance(s) with a different chemical composition and properties

Question 13

What are the most common SI Base Units?

Answer 13

Length = Meter = m
Mass = Kilogram = kg
Time = Second = s
Temperature = Kelvin = K
Amount of substance = Mole = mol

Question 14

What are the most common Metric prefixes?

Answer 14

Mega- M - 10^6
Kilo - k - 10^3
Deci - d - 10^-1
Centi - c - 10^-2
Milli - m - 10^-3
Micro - u - 10^-6
Nano - n - 10^-9
Pico - p - 10^-12

Question 15

What are the equations used for temperature conversions?

Answer 15

Tk = Tc + 273.15
Tc = Tk - 273.15
Tf = Tc (9/5) + 32
Tc = (Tf - 32) (5/9)

Question 16

What is a derived unit?

Answer 16

Metric units that are combinations of base units

Question 17

What is volume?

Answer 17

The amount of space something occupies, the most common derived unit

Question 18

What is density?

Answer 18

• Another common derived unit
• Density = mass per unit volume
• Often seen in g/cm^3 or g/mL

Question 19

What are sig figs?

Answer 19

• All the certain digits and the first uncertain digit
  of a measurement
• Indicate precision in a measurement or
  experiment

Question 20

How do you count sig figs?

Answer 20

• Non-zeros are always significant
• There are three types of zeros
  
  • Leading zeros are not significant
  • Captive zeros are always significant
  • Trailing zeros are significant if the number has
    a decimal point
• Exact numbers have no effect on the number of
  significant numbers

Question 21

What is an exact number?

Answer 21

Units that can’t be measured
- Counted objects
- Defined amounts
- Formula numbers
- Etc.

Question 22

How do you decide sig figs when using addition and subtraction?

Answer 22

• The result has the same number of decimal
  places as the least precise measurement used in
  the calculation
• It’s possible to gain sig figs by addition and to lose them by subtraction

Question 23

How do you decide sig figs when using multiplication and division?

Answer 23

The result has the same number of significant figures as the least precise measurement used in the calculation

Question 24

How do you decide sig figs when doing combined calculations?

Answer 24

• In a series of calculations, don’t round (to adjust
  the significant figures) until the end
• For different kinds of operations, evaluate the
  sig figs in the intermediate answer then do the
  remaining steps

Question 25

What is accuracy?

Answer 25

How close a particular value is to the true or accepted value

Question 26

What is precision?

Answer 26

Reproducibility, how close several measurements are to each other

Question 27

What are conversion factors?

Answer 27

Relationships between two different units
- multiplying by a conversion factor is like
multiplying by 1
- arrange conversion factors so the given unit
cancels to the desired unit
- combine as many conversion factors as
necessary, but all units must cancel except the
desired unit