3rd Assesment Moles

Question 1

Avogadro constant

Answer 1

the number of atoms, molecules, or ions in a mole of any substance (i.e., 6.02 × 10-23 per mol)

Question 2

Concentration

Answer 2

the amount of a substance dissolved in a given volume of liquid

Question 3

Limiting reactant

Answer 3

the reactant in a chemical reaction that when used up causes the reaction to stop

Question 4

Mole

Answer 4

the amount of substance in the relative atomic or formula mass of a substance in grams

Question 5

Relative atomic mass Ar

Answer 5

the average mass of the atoms of an element compared with carbon-12 (which is given a mass of exactly 12). The average mass must take into account the proportions of the naturally occurring isotopes of the element

Question 6

Relative formula mass Mr

Answer 6

the total of the relative atomic masses, added up in the ratio shown in the chemical formula, of a substance

Question 7

Law of conservation of mass:

Answer 7

Total mass of reactants=total mass of products

No atoms can be created or destroyed but only transferred

Question 8

Molecular formula

Answer 8

Show actual amount of atoms in a molecule

Question 9

Empirical formula

Answer 9

Shows the simplest ratio of atoms which make up a molecule

Question 10

Amount of moles(n)=

Answer 10

Relative formula mass mol/g (mr)

Question 11

Concentration g/dm3=

Answer 11

Mass of solute (g). Or. Mass of solute (g)
—————– —————– *1000
Volume of solution (dm3). Volume of solution(cm3)

Question 12

Mole (n) =

Answer 12

Concentration mol/dm3 (c) * volume dm3 (v)

Question 13

Percentage yield=

Answer 13

Real yield
———– *100
Theoretical yield

Question 14

Atom economy %=

Answer 14

Total relative molecular mass of all reactants

Question 15

Mass increase in reactions=

Answer 15

Corrosion of metal where oxygen atoms from the atmosphere are added to the metal

Question 16

Mass decrease in a reaction

Answer 16

Zinc +hydrochloric acid -hydrogen gas is produced and can escape
Or
Burning of wood- gases such as carbon dioxide and water are produced and can escape

Question 17

Avogadro’s law states

Answer 17

Equal volumes of all gases, under the same conditions of temperature and pressure contain the same number of moles or molecules. If the volume is 24dm3 at room temperature and pressure, this number, once again, is avogadro’s constant

Question 18

The atom economy

Answer 18

Of a reaction describes the percentages of the reactants that end up as useful products

Question 19

Concentration-

Answer 19

The mass of solute in a given volume

Question 20

1dm3=

Answer 20

1000cm3

Question 21

Slapn salts are all soluble
All nitrates are soluble
All sulfates except barium, mercury or lead
All chlorides except for silver and lead
And calcium sulfate is slightly soluble too

Answer 21

S-odium Na+
L-ithium li+
A-mmonium NH4 +
N-nitrate NO3 -