stoichiometry

Question 1

define relative mass

Answer 1

it is the ratio of the mass of one particle to 1/12 the mass of an atom of carbon-12.

Question 2

define isotopes

Answer 2

they are atoms of the same element with the same number of protons but different number of neutrons

Question 3

define relative isotopic mass of an isotope

Answer 3

it is the ratio of the mass of one atom of the isotope to 1/12 of an atom of carbon-12.

Question 4

define relative atomic mass of an element

Answer 4

it is the ratio of the average mass of an atom in the isotopic mixture to 1/12 the mass of an tom of carbon-12.

Question 5

define relative molecular mass of a molecule

Answer 5

it is the ratio of the average mass of a molecule to 1.12 the mass of an atom of carbon-12.

Question 6

what is the relative formula mass for ionic compounds.

Answer 6

it is the sum of Ar of every atom present in its formula unit.

Question 7

how many dps do we leave Ar in

Answer 7

1 dp

Question 8

define molar mass

Answer 8

it is the mass of 1 mole of substance.

Question 9

what is Avogadro’s Law?

Answer 9

it states that equal volumes of all gases under the same conditions of temperature and pressure contain the same numer of molecules/atoms.

mole ratio = volume ratio

Question 10

define molar volume

Answer 10

it is the volume occupied by 1 mole of the gas.

Question 11

what is the molar volume at stp and at rtp?

Answer 11

stp: 22.7 dm^3 mol^-1.

rtp: 24.0 dm^3 mol^-1

Question 12

what remains constant after dilution? What is the formula to use for dilution questions?

Answer 12

no. of moles of solute remain constant.

formula: CoVo = C1V1

Question 13

what to take note of during volumetric analysis

Answer 13

a portion of a solution may be taken out of the original volume to conduct reaction. normally its 25.0/250 cm^3.

either have to x10 or /10 by in working.