Chemistry: Quantitative Chemistry

Question 1

What symbolises relative formula mass

Answer 1

Mr

Question 2

what symbolises relative atomic mass

Answer 2

Ar

Question 3

what is the percentage mass of an element in a compound formula

Answer 3

Percentage mass of an element in a compound = Ar x number of atoms of that element / Mr of the compound

Question 4

what is a mole

Answer 4

atoms or molecules of any given substance will have a mass in grams equal to the relative formula mass

Question 5

give an example of moles for carbon 12

Answer 5

Carbon has an Ar of 12 so one mole weighs exactly 12g

Question 6

What is the moles equation

Answer 6

Number of moles = mass in g / Mr

Question 7

what is the conservation of mass

Answer 7

theory that the mass of reactants is equal to mass of the products

Question 8

what is a limiting reactant

Answer 8

Reactant that runs out before the others causing the reaction to stop

Question 9

what is the volume of any gas at 20C

Answer 9

24dm3

Question 10

what is the volume of gas equation

Answer 10

volume of gas = (mass of gas / Mr of gas) x 24

Question 11

what are the two concentration equations

Answer 11

1. concentration = mass of solute / volume of solvent

2. concentration = number of moles of solute / volume of solvent

Question 12

what is atom economy

Answer 12

percentage of reactants that form useful/desired products

Question 13

what is the atom economy equation

Answer 13

atom economy = (relative formula mass of desired products / relative formula mass of reactants) x 100

Question 14

what is percentage yield

Answer 14

the overall success of the reaction

Question 15

what is the percentage yield equation

Answer 15

percentage yield = mass of product actually made / maximum theoretical mass of product