Stoichiometry Flashcards

1
Q

What must we use because we use large amounts of molecules and atoms in the real world?

A

Average masses in calculations

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2
Q

What is average atomic mass also known as?

A

atomic weight

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3
Q

How is the average atomic mass calculated?

A

Calculated from the isotopes of an element weighted by their relative abundances.

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4
Q

What is the percentage of an element that is 1 isotope called?

A

natural abundance

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5
Q

When is mass spectrometry used?

A

It is used when the masses of atoms and the percent abundances of isotopes of elements are measured.

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6
Q

What is mass spectrometry?

A

separates particles according to their mass

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7
Q

What is a mole (mol)?

A

a counting unit

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8
Q

What does moles help with?

A

Help provide a bridge from the real world scale to the molecular scale.

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9
Q

What is Avogadro’s number?

A

6.022 x 10^23

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10
Q

What does a mole allow us to relate?

A

mass to atoms of a substance

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11
Q

What is molar mass?

A

It is the mass of 1 mol of a substance (g/mol)

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12
Q

Where do we find the molar mass of an element?

A

on the periodic table

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13
Q

What is an empirical formula?

A

the lowest whole-number ratio of atoms of each element in a compound

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14
Q

What is percent composition?

A

the percentage by mass contributed by each element in the substance

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15
Q

Are the formulas obtained from percent compositions always the empirical formula?

A

YES ALWAYS

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16
Q

What is a molecular formula?

A

Gives the exact number of atoms of each element in a compound

17
Q

What are chemical equations?

A

concise representations of chemical reactions

18
Q

What do letters in parentheses represent?

A

states of matter

19
Q

Where are the reactants and products located in a chemical equation?

A

reactants: left side
products: right side

20
Q

What do the subscripts tell you in a chemical euqation?

A

the number of atoms of each element in a molecule

21
Q

What do the coefficients tell you in a chemicals equation?

A

tell the number of molecules (used to balance equation)

22
Q

Which of the following quantities must always be the same on both sides of a chemical equation?

A
  • same number of atoms of each kind

- the sum of the masses of all substances involved

23
Q

What is stoichiometry?

A

the quantitative study of the amounts of reactants and products in chemical reactions