Section 1 - Key concepts - Mass, empirical formula, moles, limiting reactants and balancing equations Flashcards
What is the conservation of mass?
During a chemical reaction, no atoms are destroyed or created
What is a closed system?
A system where nothing can get in or out
What is the relative formula mass, Mr, of a compound?
The relative atomic mass, Ar, of all atoms in its formula added together
What does empirical formula tell you?
The smallest whole number ratio of atoms in a compound
What is Avogadro’s constant?
6.02 x 10^23
What does Avogadro’s constant tell us?
One mole of atoms or molecules of any substance will have a mass in grams equal to relative particle mass for that substance
Formula for number of moles in a certain mass of something?
Number of moles = mass in g (of element or compound) ÷ Mr (of compound) or Ar (of element)
How would you find the number of particles in a substance?
Find number of moles for that particular substance then multiply moles by Avogadro’s constant
Formula for finding concentration from mass of solute?
Concentration (g dm^-3) = mass of solute (g)÷ volume of solution (dm³)
What is a limiting reactant?
The reactant that’s used up in a reaction
