Formulas Flashcards
(32 cards)
what is the formula for molarity (M)?
moles of solute/liters of solution
what is the formula for density (P)?
mass (g)/vol (cm^3)
what is the formula to calculate the # of molecules?
(moles)(6.02 x 10^23)
what is the formula to calculate the # of moles?
mass (g)/molecular weight
what is the formula to calculate the mole fraction?
of moles in solute/total # of moles in solution
What is the empirical formula?
The simplest whole-number ratio of atoms of each element in a compound.
What does the molecular formula represent?
The actual number of atoms of each element in a molecule of a compound.
True or False: The empirical formula can be the same as the molecular formula.
True.
What is the formula for percent composition?
Percent Composition = (mass of element in 1 mole of compound / molar mass of compound) x 100.
Fill in the blank: The limiting reagent is the reactant that _______.
is completely consumed in a chemical reaction.
What is theoretical yield?
The maximum amount of product that can be produced from a given amount of reactants.
True or False: Theoretical yield is always greater than or equal to actual yield.
True.
What is the purpose of identifying the limiting reagent?
To determine which reactant will run out first and thus limit the amount of product formed.
How can you calculate the theoretical yield?
By using stoichiometric calculations based on the limiting reagent.
What is the relationship between empirical formula and molecular formula?
The molecular formula is a whole-number multiple of the empirical formula.
Multiple Choice: Which of the following is NOT a method to find the empirical formula? A) Mass percent composition B) Combustion analysis C) Titration D) Mole ratio
C) Titration.
What is the unit of measurement for percent composition?
Percentage (%).
Fill in the blank: The actual yield is the _______ obtained from a reaction.
amount of product actually produced.
How do you convert from empirical to molecular formula?
Multiply the empirical formula by the ratio of the molecular weight to the empirical formula weight.
True or False: Theoretical yield can be calculated without knowing the limiting reagent.
False.
What is the first step in determining the limiting reagent?
Calculate the number of moles of each reactant.
Multiple Choice: If 2H2 + O2 → 2H2O, which is the limiting reagent if you have 3 moles of H2 and 1 mole of O2? A) H2 B) O2 C) Both D) None
B) O2.
What is the significance of percent composition in chemistry?
It helps to understand the proportion of each element in a compound.
Fill in the blank: To find the empirical formula from percent composition, convert percentages to _______.
moles.
