chapter 5 - quantifying chemistry Flashcards

1
Q

what is carbon-12 used for?

A

it is used as the standard for comparing relative isotopic masses as it is stable and abundant

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2
Q

what is the mass spectrometer

A

helps to determine the relative isotopic masses of the different isotopes of an element and abundance

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3
Q

what does the mass spectrometer tell us

A
  • the number of isotopes in a given sample of an element
  • the relative isotopic mass of each isotope
  • the percentage abundance of the isotopes
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4
Q

how to calculate the relative atomic mass (Ar)

A

(RIM of isotope times aunbdance) + …….. over 100

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5
Q

define relative atomic mass - Ar

A

the mean mass of the naturally occurring mixture of the isotopes of an element on the relative atomic mass scale,
by comparing masses against the mass of carbon -12

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6
Q

define relative isotopic mass - RIM

A

the mass of an individual isotope of an element on the relative atomic mass, by comparing masses against the mass of carbon-12

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7
Q

what is n

A

= the number of moles (6.02 times 10^23)

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8
Q

what is m

A

the mass of the sample

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9
Q

what is M

A

the molar mass of the sample

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10
Q

what is the mole

A

6.02 times 10^23

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11
Q

what is the unit for M

A

g/mol = grams per mole

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12
Q

what is the unit for m

A

g = grams

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13
Q

how do you find the number of moles

A

n = m/M

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14
Q

how do you find the m (mass)

A

m = nM

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15
Q

how do you find the M (molar mass)

A

M = m/n

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16
Q

number of particles - to - moles

A

divide by Na

17
Q

moles - to - number of particles

A

multiply by Na

18
Q

what is Na

A

Avogadro’s number = 6.02 times 10^23

19
Q

define empirical formula

A

the E.F shows the simplest numerical ratio in which atoms are combined

20
Q

define molecular formula

A

the M.F is the actual number of atoms of each element in a molecule of a substance

21
Q

fine percentage composition

A

list of percentages by mass of the elements in a compound