Topic 1 : Stoichiometric Relationships

Question 1

Solvent

Answer 1

the dissolving medium (usually water)

Question 2

Solute

Answer 2

the substance that is dissolved

Question 3

Solution

Answer 3

solvent and solute when mixed together intimately so that the solid phase becomes indistinguishable from the liquid phase.

Question 4

Concentration (definiton)

Answer 4

the amount of solute per volume of solution (units mols per dm3 (litre) or grams per litre)

Question 5

Relative Atomic Mass

Answer 5

1. weighted average of all the masses of the isotopes of an element
2. the average mass of atoms of the element on a scale in which an atom of C(12) has a mass of exactly 12 units
3. written as Ar

Question 6

Moles

Answer 6

Moles = mass (g) / Molar Mass (g/mol)

Question 7

% Atom economy

Answer 7

% Atom Economy = (Molar mass of atoms of useful products/ Molar mass of atoms in reactant) x 100%

Question 8

Molar concentration

Answer 8

Moles = molar concentration (mol/dm^3) * volume (dm^3)

Question 9

Acids + metal

Answer 9

salt + hydrogen

Question 10

Acid + bases

Answer 10

salt + water

Question 11

acids + carbonates

Answer 11

salt + water + carbon dioxide

Question 12

no of moles (in solutions)

Answer 12

Number of moles = volume used(dm^3) x concentration

Question 13

Volume formula of gas at RTP

Answer 13

Volume of gas (dm^3) = moles * 24

Question 14

Avogadros number

Answer 14

6.022 * 10^23

Question 15

Number of molecules

Answer 15

number of molecules = number of moles * Avogadros number

Question 16

Relative molecular mass

Answer 16

1. Relative molecular mass is the sum of the relative atomic masses of all the atoms in the molecular formula
2. Written as Mr

Question 17

Molar mass

Answer 17

the mass of a substance per one mole expressed in g mol−1

Question 18

Ideal gas law

Answer 18

1. pV = nRT

2. nR = p1v1/t1 = p2v2/t2

Question 19

Ideal gas law rules

Answer 19

1. The volume of a given amount of gas is inversely proportional to its pressure when temperature is held constant (Boyle’s law)
2. For a constant volume and amount of air, the pressure and temperature are directly proportional
3. For constant pressure, volume and time are directly proportional

Question 20

Theoretical yield

Answer 20

Theoretical yield is the maximum quantity of product that can be obtained from given quantities of reactants, assuming completion

Question 21

Limiting reagent

Answer 21

Limiting reagent/reactant is the reactant that determines the theoretical yield of a product, after the reaction is complete there will be none left

Question 22

Excess reagent

Answer 22

Excess reagent/reactant is the reactant that is not used up by the reaction, after the reaction is complete this substance will still be present

Question 23

Volume formula of gas at STP

Answer 23

Volume of gas (dm^3) = moles * 22.7