Unit 3 Test Flashcards
(14 cards)
What is the formula for calculating moles from mass?
n = \frac{m}{M} \quad \text{(moles = mass ÷ molar mass)}
Define a mole.
A mole represents 6.022 × 10²³ particles (atoms, molecules, or ions) of a substance.
How do you calculate the number of particles in a substance?
\text{Particles} = n x 6.022 x 10^{23}
What is molar mass?
The mass of one mole of a substance (g/mol), found by summing atomic masses of all atoms in the formula.
What is percentage composition?
The percent by mass of each element in a compound.
Formula for percentage composition?
\% = \left( \frac{\text{mass of element}}{\text{molar mass of compound}} \right) \times 100
What is an empirical formula?
The simplest whole number ratio of atoms in a compound.
Steps to find empirical formula?
- Convert % to g
- Convert g to mol
- Divide by smallest mole value
- Multiply to get whole numbers
Formula for molecular formula?
\text{Molecular Formula} = \text{Empirical Formula} \times n \quad \text{where } n = \frac{\text{molar mass}}{\text{empirical formula mass}}
What is a limiting reactant?
The reactant that is completely used up in a reaction and limits the amount of product formed.
What is an excess reactant?
The reactant that is not completely used and remains after the reaction is complete.
How do you calculate percentage yield?
\% \text{Yield} = \left( \frac{\text{Actual Yield}}{\text{Theoretical Yield}} \right) \times 100
What is theoretical yield?
The maximum amount of product that can be formed from a given amount of reactant (based on stoichiometry).
What is actual yield?
The amount of product actually obtained from an experiment.
