Cp 5 Flashcards
(20 cards)
What is a word equation?
A chemical reaction written using the names of reactants and products.
What is a symbol (chemical) equation?
A reaction using chemical symbols; it must be balanced.
What are the four state symbols used in equations?
(s) solid, (l) liquid, (g) gas, (aq) aqueous.
What is relative atomic mass (Ar)?
The weighted average mass of an atom compared to 1/12 of the mass of a carbon-12 atom.
Why is Ar not always a whole number?
Because most elements exist as mixtures of isotopes.
What is relative molecular mass (Mr)?
The sum of relative atomic masses of all atoms in a molecule.
What is relative formula mass (Mr)?
The sum of relative atomic masses of atoms in a formula unit of an ionic compound.
How do you calculate percent composition of an element in a compound?
(Mass of element / Mr) × 100%
What is a mole (mol)?
The amount of substance containing 6.02 × 10^23 particles (Avogadro’s number).
What is molar mass?
The mass of one mole of a substance in grams.
How do you calculate moles from mass?
Moles = Mass / Molar mass
What is Avogadro’s constant?
6.02 × 10^23 particles per mole.
What is the empirical formula?
The simplest whole number ratio of atoms of each element in a compound.
What is the molecular formula?
The actual number of atoms of each element in a molecule.
How do you determine the empirical formula?
- Find moles, 2. Divide by smallest value, 3. Write whole number ratio.
How do you determine the molecular formula?
Divide molecular mass by empirical formula mass and multiply the empirical formula.
What is percentage yield?
(Actual yield / Theoretical yield) × 100%
What is percent purity?
(Mass of pure substance / Total mass) × 100%
What is a limiting reactant?
The reactant that is completely used up in a reaction, limiting the amount of product.
What does ‘in excess’ mean in a chemical reaction?
The reactant that is not completely used up during the reaction.
