Topic 5: Calculations in Chemistry Flashcards

1
Q

What does Ar stand for?

A

-Relative atomic mass.

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2
Q

What does Mr stand for?

A

-Molecular mass.

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3
Q

How much is s mole of carbon?

A

-12 grams.

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4
Q

How do you work out the relative atomic mass? (Formula)

A

-No. protons + No. Neutrons in an atom.

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5
Q

What is an isotope?

A

-Same elements have atoms with a different number of neutrons. the amount of isotopes that occur naturally is its relative abundance.

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6
Q

Calculating the Ar using abundance?

A

-Ar = (abundance 1) x (mass1) + (abundence 2) x (mass 2) / 100.

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7
Q

1 mole =

A
  • 6 x 10 to the power of 23.
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8
Q

Equation: No. moles =

A

-Mass (g) / Ar or Mr.

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9
Q

Mass (g) = the what?

A

-Mr or Ar mole.

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10
Q

What does the empirical formula do?

A

-Turns C2H6 to CH3.

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11
Q

What is the reacting masses?

A

-The reacting masses tells us the maximum possible yield of a reaction.

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12
Q

What does, s, l, g, aq mean

A

-Solids, liquids gases and aqueous solutions.

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13
Q

You can have a mole of….

A

-Anything.

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14
Q

What is the definition of Relative atomic mass?

A

-Measure of the mass of one atom of the element.

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15
Q

How to calculate the relative formula masses (Mr) from the (Ar)

A

-For example CO2 carbon is 12 + plus 16 x 2 = the Mr.

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16
Q

S means?

A

-solid

17
Q

L means?

A

-liquid

18
Q

G means?

A

-gas

19
Q

Aq means?

A

-aqueous solutions

20
Q

Avogadro’s number is?

A

-A mole 6 x 10 to the power of 23

21
Q

Equation: Mass =

A

Mr x Mol

22
Q

Sample of copper, 69.1% of atoms have mass of 63 and the rest have mass number of 65. Find Relative Atomic mass.

A

Isotope 65 is 30.9%
(0.691 x 63) + (0.309 x 65)
= 63.6

23
Q

Moles =

A

Mass/Mr

24
Q

Mr =

A

Mass/mol

25
Q

Conc =

A

mols/vol