Topic 5: Calculations in Chemistry Flashcards
What does Ar stand for?
-Relative atomic mass.
What does Mr stand for?
-Molecular mass.
How much is s mole of carbon?
-12 grams.
How do you work out the relative atomic mass? (Formula)
-No. protons + No. Neutrons in an atom.
What is an isotope?
-Same elements have atoms with a different number of neutrons. the amount of isotopes that occur naturally is its relative abundance.
Calculating the Ar using abundance?
-Ar = (abundance 1) x (mass1) + (abundence 2) x (mass 2) / 100.
1 mole =
- 6 x 10 to the power of 23.
Equation: No. moles =
-Mass (g) / Ar or Mr.
Mass (g) = the what?
-Mr or Ar mole.
What does the empirical formula do?
-Turns C2H6 to CH3.
What is the reacting masses?
-The reacting masses tells us the maximum possible yield of a reaction.
What does, s, l, g, aq mean
-Solids, liquids gases and aqueous solutions.
You can have a mole of….
-Anything.
What is the definition of Relative atomic mass?
-Measure of the mass of one atom of the element.
How to calculate the relative formula masses (Mr) from the (Ar)
-For example CO2 carbon is 12 + plus 16 x 2 = the Mr.
S means?
-solid
L means?
-liquid
G means?
-gas
Aq means?
-aqueous solutions
Avogadro’s number is?
-A mole 6 x 10 to the power of 23
Equation: Mass =
Mr x Mol
Sample of copper, 69.1% of atoms have mass of 63 and the rest have mass number of 65. Find Relative Atomic mass.
Isotope 65 is 30.9%
(0.691 x 63) + (0.309 x 65)
= 63.6
Moles =
Mass/Mr
Mr =
Mass/mol
Conc =
mols/vol
