Unit 3-- Quantities in Chemical Reactions

Question 1

Significant digits

Answer 1

Digits you record when you measure something

Question 2

Rules for determining Significant digits (1)

Answer 2

1. all non-zeros #s are significant

Question 3

Rules for determining Significant digits (2)

Answer 3

All zeros that are located between 2 non-zeros are significant

Question 4

Rules for determining Significant digits (3)

Answer 4

Zeros that are located to the left of a value are not significant

Question 5

Rules for determining Significant digits (4)

Answer 5

Zeros to the right of a non-zero that is a decimal are significant

Question 6

Rules for determining Significant digits (5)

Answer 6

zeros that are located to the right of a value that is not a decimal are not significant digits

Question 7

Calculations with significant Digits

Answer 7

Multiplying and dividing

-The value with the fewest number of significant digits, going into the calculations determines the number of significant digits

Adding & subtracting
-The value with he fewest number of decimal places, going into the calculation, determines the number of places that you should repeat in the answer

Question 8

scientific notation

Answer 8

used to simplify very large and very small numbers

Question 9

Agrodavo’s Constant/ Avagadro’s number

Answer 9

6.02 x 10^23

Question 10

Small amounts of matter contain a very large number of atoms and are counted in quantities called…

Answer 10

MOLES

Question 11

Formula Unit

Answer 11

Metal + Non-metal held together by an ionic bond

Question 12

Mole equation ( to count atoms and molecules)

Answer 12

n= N/NA

Question 13

n

Answer 13

Number of moles ( mol)

Question 14

N

Answer 14

Number of atoms (at)/ molecules (molec)/ or formula units ( fu)

Question 15

NA

Answer 15

Avogadro’s constant

Question 16

Ending for atoms

Answer 16

atoms/mole

Question 17

Endings for molecule

Answer 17

Molecules/mole

Question 18

Ending for Formula Units

Answer 18

Formula Units/ mole

Question 19

Molar Mass (M)

Answer 19

the mass in grams (g) of 1 mole of a substance and is equal to the atomic mass of an element or the molecular mass of a molecule

Question 20

Molar Mass is expressed as…

Answer 20

** g/mol **

Question 21

Calculating molar mass

Answer 21

The molar mass of a compound can be determined by adding the atomic masses of elements in the compound

Question 22

Calculating Moles/ formula ( given the mass and given the moles)

Answer 22

n= m/M

Question 23

n

Answer 23

Number of moles (mol)

Question 24

m

Answer 24

mass

Question 25

M

Answer 25

Molar Mass (g/mol)
This is calculated from the periodic table

Question 26

Law of definite proportions

Answer 26

A law stating that a chemical compound always contains the same amount proportions of elements by mass

Question 27

Mass Percent

Answer 27

The mass of an element in a compound, expressed as a percentage of the total mass of the compound

Question 28

Percentage composition

Answer 28

The percent by mass of each element in a compound