chemical calculations 1.3

Question 1

what is the definition of relative atomic mass

Answer 1

mean mass of an atom of an element divided by 1/12 of mean mass of an atom of carbon-12 isotope

Question 2

what is the definition of relative molecular mass

Answer 2

mean mass of a molecule of a compound divided by 1/12 of the mean mass of an atom of carbon-12

Question 3

definition of relative isotopic mass

Answer 3

mean mass of an atom of an isotope divided by 1/12 of the mean mass of carbon-12

Question 4

purpose of mass spectrometry

Answer 4

used to identify and find overall relative atomic mass

Question 5

what is the time of flight mass spectrometry

Answer 5

records time it takes for ions of each isotope to reach detector. using this a spectra can be produced showing each isotope present

Question 6

what is the ionisation step of (TOF)

Answer 6

sample of an element is vapourised and injected into the mass spectrometer. high voltage is passed over chamber leaving 1+ ions

Question 7

what is the acceleration step of TOF

Answer 7

positively charged ions are accelerated toward negative detection plate

Question 8

what is ion drift step of TOF

Answer 8

deflected by magnetic field into a curved path. the radius of their path is dependent of the charge and mass of the ion

Question 9

what is the detection step of TOF

Answer 9

1+ ion hit by negative detection plate, they gain an electron producing a flow of charge. greater the abundance, the greater current produced

Question 10

what is the analysis step of TOF

Answer 10

current values are then used in combination with the flight times to produce a spectra print with relative abundance of each isotope displayed

Question 11

what is the definition of empirical formula

Answer 11

simplest whole number ratio of atoms of each element in a compound. found using molar ratios

Question 12

what is the definition of molecular formula

Answer 12

true number of each atom in the molecule.

Question 13

whats the definition of moles and avogadro constant

Answer 13

standard unit of measurement for substances which contains same number of particles as avogadros constant

Question 14

what is the definition of molar volume

Answer 14

a mole of atoms will always occupy the same volume under standard conditions. if temperature or pressure change, vol change

Question 15

what is the formula for atom economy

Answer 15

mr of desired product/ mr of reactants X 100

Question 16

what is the percentage yield formula

Answer 16

experimental mass/ theoretical mass x 100