Mole Concept and Stoichiometry

Question 1

What is atomic number?

Answer 1

The number of protons in an atom of an element.

Question 2

What is nucleon number?

Answer 2

Total number of protons and nucleons in an atom of an element.

Question 3

What is an isotope?

Answer 3

Atoms with the same proton number but different nucleon numbers ie different number of neutrons.

Question 4

What is relative atomic mass?

Answer 4

(weighted average mass of 1 atom of the element) / 1/12(mass of 1 atom of carbon-12)

Takes into consideration the isotopes and their relative abundancies.

Question 5

What is relative isotopic mass?

Answer 5

mass of 1 atom of the isotope / 1/12(mass of 1 atom of carbon-12)

Question 6

What is relative molecular mass?

Answer 6

weighted average mass of 1 molecule of the substance / 1/12(mass of 1 atom of carbon-12)

Used when referring to the relative masses of molecular elements or covalent compounds.

Question 7

What is relative formula mass?

Answer 7

weighted average of 1 formula unit of substance / 1/12(mass of 1 atom of carbon-12)

used when referring to the relative masses of ions and ionic compounds

Question 8

What is the mole?

Answer 8

It is the amount of that substance that contains 6.02x10623 elementary entities of that substance.

Question 9

What is empirical formula?

Answer 9

The formula that shows the simplest whole number ratio of the atoms of different elements present in one molecule or formula unit of the compound.

Question 10

What is the molecular formula?

Answer 10

The formula that shows the exact number of atoms of elements present in one molecule of the compound.

Question 11

What is percentage yield?

Answer 11

(Actual yield / Theoretical yield) x 100%

Question 12

What is Avogadro’s Law?

Answer 12

Equal volumes of all gases under the same conditions of temperature and pressure contain the same number of molecules.

Question 13

Molar volumes at stp and rtp:

Answer 13

stp: 22.7 dm^3 mol^-1
rtp: 24 dm^3 mol^-1