Mole Concept and LCM Flashcards
(14 cards)
Q: What is a mole in chemistry?
A: A mole is a quantity that contains exactly 6.02 × 10²³ particles (Avogadro’s number).
Q: What is the molar mass of a substance?
A: The mass of one mole of a substance in grams. It’s the sum of the relative atomic masses (Ar) of all atoms in the formula.
Q: What is the law of conservation of mass?
A: Matter is neither created nor destroyed in a chemical reaction. The total mass of reactants equals the total mass of products.
Q: What is the formula linking mass, moles, and molar mass?
n (moles) = m (mass) / M (molar mass)
Q: What is the process to find the number of representative particles from moles?
Particles= n × 6.02 × 10²³
Q: How do you calculate mass from moles and molar mass?
m=n×M
Q: How do you find moles from a given number of particles?
n = particles / (6.02 × 10²³)
Q: What is percentage composition?
A: The percentage by mass of each element in a compound.
Q: How is percentage composition calculated?
%= ( (Molarmassofcompound) / (Massofelementin1mol) ) ×100
Q: What is an empirical formula (EF)?
A: The simplest whole-number ratio of atoms of each element in a compound.
Q: What is a molecular formula?
A: The actual number of atoms of each element in a molecule.
Q: How do you determine the empirical formula from % composition?
Assume 100 g sample → grams = percentages
Convert each to moles
Divide all by smallest number of moles
Multiply to get whole numbers if needed
Q: How do you find the molecular formula from EF?
Calculate molar mass of EF
Divide molecular molar mass by EF molar mass
Multiply EF by that ratio
Q: What type of compound has a formula unit instead of a molecular formula?
A: Ionic compounds.
