mole concept

Question 1

what is the relative atomic mass?

Answer 1

average mass of one atoms of that element compared to 1/112 of the mass of one carbon-12 atom

Question 2

what is the relative molecular mass?

Answer 2

average mass of one molecule of that substance compared to one twelfth of the mass of one atom of carbon-12 atom

Question 3

how many particles are in a mole?

Answer 3

6 x 10^23 particles

Question 4

what is avogadro’s constant/number?

Answer 4

6 x 10^23

Question 5

what is the relationship between no. of moles and no. of particles?

Answer 5

no. of moles = no. of particles / 6x10^23

Question 6

what is the si unit of no. of moles?

Answer 6

mol

Question 7

what is the relationship between mass of substance, Mr and no. of moles?

Answer 7

mass of substance (g) = Mr x no. of moles

Question 8

what is avogadro’s law?

Answer 8

equal volumes of all gases under the same temperature and pressure contain the same number of particles

Question 9

what is the volume occupied by 1 mole of gas at room temperature and pressure?

Answer 9

24 dm^3 = 24000 cm^3

Question 10

what is the relationship between volumes of gases and the number of moles of the gas?

Answer 10

the volume of gas is proportional to the number of moles of the gas

Question 11

what is the relationship of the volume of gas, no. of moles and the molar volume?

Answer 11

volume of gas (dm^3) = no. of moles x 24 (dm^3)

Question 12

what is the empirical formula?

Answer 12

simplest formula of a compound

Question 13

what is the molecular formula?

Answer 13

the exact number of atoms in a compound

Question 14

what is the limiting reactant?

Answer 14

completely used up in the reaction

Question 15

what is the relationship of the volume of gas, no. of moles and the molar volume?

Answer 15

the volume of gas (dm^3) = no. of moles x 24 (dm^3)

Question 16

what is the relationship between the mole concentration and no. of moles?

Answer 16

no, of moles (mol) = volume of solution (dm^3) x mole concentration (mol/dm^3)

Question 17

what is the relationship between mole concentration and mass concentration?

Answer 17

mass concentration (g/dm^3) = Mr x mole concentration (mol/dm^3)

Question 18

what is the relationship between mass concentration and mass of solute?

Answer 18

mass of solute (g) = mass concentration (g/dm^3) x volume of sol (dm^3)

Question 19

how do you find percentage by mass of an element in a compound?

Answer 19

(Ar x no. of atoms of element/Mr of the compound) x 100 percentage

Question 20

what is the formula for percentage purity?

Answer 20

(mass of pure substance /mass of given sample) x 100

Question 21

how do you calculate percenatge yield?

Answer 21

(actual yield/expected yield) x 100