Few Flashcards

0
Q

Avogrado’s number

A

Number of particles found in one mole of a substance

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1
Q

Mole

A

Chemical mass unit 6.022 • 10^23 molecule/atoms/or other unit

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2
Q

Molar mass

A

The mass of one mole of a substance, usually expressed in grams or kilograms

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3
Q

Percent composition

A

The percentage by mass of each element in a compound

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4
Q

Empirical formula

A

Formula that shows the ratio of elements present in the compound. Ratios are denoted by subscripts next to the element symbol

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5
Q

Molecular formula

A

Expression that states the number and type of atoms present in a molecule of a substance

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6
Q

step one for conversions?

A

known over 1

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7
Q

how do I calculate percent composition?

A

% mass = grams of element
___________________ x 100
total grams of compound

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8
Q

how do I find molar mass?

A

you look at a periodic table and look at the mass of the element ( if there is a coefficient that’s is bigger than 1 you multiply the mass times the coefficient. you do the same for the rest of the elements and add it all up. your total is your molar mass.

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9
Q

how do I calculate the empirical formula?

A
  1. ) pretend you have 100 gram sample of the compound (just change the % to grams)
  2. ) convert the grams to moles for each element
  3. ) divide each # of moles by the same smallest #
  4. ) IF NEEDED, multiply the result to get whole numbers. NO DECIMALS!!
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10
Q

how do I calculate molecular formula?

A

take or solve for empirical formula
solve molar mass of molecular formula and empirical formula.
divide molecular formula molar mass by empirical formula’s molar mass.

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11
Q

moles road map

A
Volume 
22.4L
\_\_\_\_\_
Mole↓
    ↓
Mole
↙            ↘
Mass             representative particles
G/moles               6.02x10^23 RP
                                      Rp= atoms/molecules/formula/
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12
Q

grams to grams

A

grams x moles x moles x grams
known over 1 x
1 mole of known compound over molar mass of known compound x
moles of unknown compound over moles of known compound x
mass of unknown compound over 1 mole of unkown compund

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13
Q

limiting reactant

A

TWO grams to grams to grams.

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14
Q

which one will be your limiting reactant?

A

smallest product

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15
Q

percent yield formula

A

Actual yield
___________ x 100%
theoretical yield

16
Q

what do you have to calculate in order to get the

TY ( theoretical yield)

A

grams to gram equation for limiting reactant

17
Q

how do you calculate the excess left over in a limiting reactant reaction?

A
subtract what you get as the smallest number after limiting reactant grams to grams equation from 
known
\_\_\_\_\_
   1
that was not used.
18
Q

process in converting moles to grams

A

put known over 1
multiply
by molar mass over one
moles cross out so answer should be in grams

19
Q

process in converting moles to moles

A

MAKE SURE EQUATION IN BALANCED
known over one
multiply times
moles of unknown over moles of known