Stociometry Flashcards

1
Q

Molar mass

A

The mass of 1 mole of a substance

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2
Q

1 mole equals how many atoms

A

6.022 x 10^23 atoms/units

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3
Q

What is the Relative Atomic Mass of atoms

A

The average of all isotopes that is usually found, also usually the atomic mass stated on an element/ Average mass of a molecule

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4
Q

Formula for finding relative atomic mass

A

Isotope A’s mass x Relative abundance of A’s atoms (decimals) + Isotope B’s mass x Relative abundance of B’s atoms (decimals)

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5
Q

What are the steps a Mass Spectromy machine uses to find the mass/charge ratio of an elements isotopes

A

Ionization: Knocks off or adds electrons
Acceleration: Speeds up ions to same speed
Deflection: Uses positive and negative magnets to deflect ions based on mass and ionization
Detection: Ion beam is detected electrically

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6
Q

Steps to balance an equation

A
  1. Write out equation
  2. List elements; Hydrogens and Oxygens last
  3. Balance 1 element w/ coefficients
  4. Check to see if equation is balanced
  5. Repeat till balanced fully
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7
Q

Formula for finding the moles of an element

A

Moles = Mass/Molecular mass

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8
Q

What is Molecular Mass

A

The addition of all atomic masses in a molecule

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9
Q

Ex. What is the number of moles in 35.0g of CuSO4?

A

Moles = Mass/Molecular mass

35.0g/(63.5 + 32.0 + 16.0 x 4) = 0.219 moles

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10
Q

Ex. What is the number of moles in 75.0mg of CaSO4 H2O?

A

Moles = Mass/Molecular mass

0.075 (mg are 100x smaller than g)/(40 + 32.0 + 16.0 x 4 + 18.0 x 2) = 4.36 x 10^ -4

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11
Q

Ex How many chloride ions are there in a 25.0 cm of a solution of magnesium chloride (MgCl) w/ a concentration of 0.400 mol/dm^3

A

Molar concentration = Concentration x Volume (M = C x V)

  1. MgCl2 = 0.400 x 0.0250 = 0.0100 moles of chlorine ions
  2. 0.0100 x 2 (Since there are 2 chlorine ions for every one mole of MgCl2)
    = 0.0200 moles
  3. Moles of chlorine ions x Avogadro’s number = 4.36 x 10^-4
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12
Q

Which version of the formula to find the number of moles is for solutions

A

Moles = concentration x volume

(C = M/V, V = M/C)

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13
Q

Which version of the formula to find the number of moles is used for pure solids, liquids, and gases only?

A

Moles = Mass/Molecular mass

(M = Mol x Mr, Mr = Mol x M)

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14
Q

1 mole = ?

A

The molar mass (Atomic mass of one atom of an element)

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