Quantifying atoms and compounds

Question 1

Mass spectrometer

Answer 1

used to confirm the existence of isotopes

Question 2

Percentage abundance using the spectrum

Answer 2

% abundance= peak height / total peak height x 100

Question 3

Mass spectrum

Answer 3

Graph of the relative mass of isotopes, calibrated on the C12 scale, plotted against the percentage abundance

Question 4

RAM calculation

Answer 4

E(RIM x %) / 100

Question 5

Mole

Answer 5

unit for counting particles

Question 6

n

Answer 6

amount in moles

Question 7

Avogadro’s number

Answer 7

6.02 x 10^23

Question 8

NA

Answer 8

Avogadro’s number

Question 9

Relative Mr

Answer 9

Molar mass

Sum of the relative atomic masses of elements in the molecular formula

Question 10

Mr

Answer 10

g mol ^-1

Mass of one mole of a particular element or compound

Question 11

n=

Answer 11

m/Mr- amount

Question 12

Stoichometry

Answer 12

n(unknown)= coefficient(unknown) / coefficient(known) x n(known)

Question 13

Percentage composition of an element

Answer 13

Mr of that element x number of atoms of that element in compound/ Mr of compound x 100

Question 14

Empirical formula

Answer 14

Shows the elements and simplest whole number ratio of atoms

Question 15

Molecular formula

Answer 15

shows exact number of atoms of each element in a molecule

Question 16

X (molecular formula)=

Answer 16

Mr(MF) / Mr(EF)

Question 17

Elemental analysis of an organic compound procedure

Answer 17

1. Mass of organic compound recorded
2. Complete combustion occurs through apparatus
3. Sodium hydroxide solution absorbs carbon dioxide in organic compound. Mass of carbon dioxide equal to mass increase of sodium hydroxide (carbon dioxide absorber)
4. Drying agents absorb water in organic compound. Mass of water is equal to mass increase of drying agents (water absorber)

Question 18

Elemental analysis to determine empirical formula

Answer 18

1. Calculate mass of carbon from mass of carbon dioxide produced via stoichometry
2. Calculate mass of hydrogen from mass of water produced
3. Subtract mass of carbon plus hydrogen from original mass to find mass of oxygen
4. Using masses of O, C and H, calculate empirical formula

Question 19

RAM

Answer 19

Weighted average of isotopic masses of atoms of an element compared to the standard C12 isotope

Question 20

n= (not mass)

Answer 20

N / NA

Question 21

N

Answer 21

number of particles-how many

Question 22

RIM

Answer 22

mass of an atom of an isotope compared to the mass of a carbon 12 atom

Question 23

Relative molecular mass

Answer 23

Mass of 1 molecule of a substance compared to the the mass of 1 atom of C12 taken as 12 exactly

Question 24

Molar mass

Answer 24

Mass, in grams, of 1 mole of a substance