chem chap 7 - mole concept and stoichiometry

Question 1

what is relative atomic mass?

Answer 1

relative atomic mass (Ar) of an element is the average mass of one atom of that element relative to 1/12 the mass of a carbon-12 atom

given in the periodic table as the nucleon number

Question 2

a sample of chlorine contains 75% of chlorine-35 and 25% of chlorine-37. calculate the Ar of chlorine

Answer 2

Ar = (75/100 x 35) + (25/100 x 37) = 35.5

Question 3

what is relative molecular mass?

Answer 3

the relative molacular mass (Mr) of a molecular substance is the average mass of one molecule of that substance relative to 1/12 the mass of an atom of carbon-12

Question 4

how to find relative molecular mass?

Answer 4

add up all the relative atomic mass of all the atoms in its chemical formula

Question 5

how many particles does one mole represent?

Answer 5

6x10²³

Question 6

formula 1: how to find the number of particles in a substance?

Answer 6

no of moles x 6x10²³

Question 7

formula 2: how to find mass in grams of a substance?

Answer 7

no of moles x Mr

Question 8

formula 4: how to find volume of gas in dm³

Answer 8

no of moles x 24dm³/24000cm³

Question 9

formula 4: how to find the mass of the solute in grams

Answer 9

no of moles x concentration (g/dm³)

Question 10

formula 5: how to find concentration of solution?

Answer 10

mass of solute (g) / vol of solvent in dm³

Question 11

what are the 3 steps to finding the volume of product produced?

Answer 11

step 1: calculate the number of moles of the reactant/ product using given info

step 2: find no of moles of the substance we are solving for using mole ratio from balanced eqn & result from step 1

step 3: calculate the ans using no of moles from step 2

Question 12

what method is used during volumetric analysis

Answer 12

titration

Question 13

what is the name for a solution of known concentration

Answer 13

titrant

Question 14

what is the name of a solution of unknown concentration

Answer 14

the analyte