Stoichiometry Flashcards
What is the difference between molecular weight and formula weight?
Molecular weight: sum of ALL atomic weights
Formula weight: sum of ALL atomic weights according to the empirical formula
Both units are in amu.
What is Avogadro’s number (NA)?
6.022 * 1023 mol
What does the empirical formula of a compound represent?
The simplest ratio of atoms in a compound.
Example: C4H8 → CH2
What does the molecular formula of a compound represent?
The exact numbers of atoms in a compund.
“regular formula”
Example: C4H8
What is the formula for percent composition by mass?
What are the four types of chemical reactions?
- combination
- decomposition
- single displacement
- double displacement (or metathesis)
What occurs during a combination reaction?
(“making”)
A + B → C
Example: 2 H2 (g) + O2 (g) → 2 H2O (g)
What occurs during a decomposition reaction?
(“breaking down” due to heat, UV light, or electricity)
A → B + C
Example: NaCl (s) → Na (s) + Cl2 (g)
What occurs during a single-displacement reaction?
One atom starts out by itself and replaces another atom in a compound, thus “displacing it”. This is also an example of a redox reaction.
A + BC → B + AC
Example: Cu (s) + AgNO3 (aq) → Ag (s) + CuNO3 (aq)
What occurs during a double-displacement (or metathesis) reaction?
Both compounds swap atoms.
AB + CD → AD + BC
Example: CaCl2 (aq) + 2 AgNO3 (aq) → Ca(NO3)2 (aq) + 2 AgCl (s)
What occurs during a neutralization reaction?
An acid reacts with a base to produce salt (and usually water).
Example: HCl (aq) + NaOH (aq) → NaCl (aq) + H2O (l)
What is the equation for percent yield?
What is equivalent weight?
Amount of substance needed to react with or supply:
- 1 mole of H+
OR
- 1 mole of e-
