2.1.3. Amount Of Substance Flashcards
What is the definition of ‘amount of substance’?
A measure of the number of entities (atoms, molecules, etc.) in a sample, measured in moles.
What is a mole (symbol ‘mol’)?
The unit for amount of substance, defined as containing exactly 6.02 x 10²³ entities.
What is the Avogadro constant (NA)?
The number of particles in one mole of a substance, equal to 6.02 x 10²³ mol⁻¹.
What is molar mass?
The mass of one mole of a substance, expressed in grams per mole (g mol⁻¹).
What is molar gas volume?
The volume occupied by one mole of a gas at room temperature and pressure, expressed in dm³ mol⁻¹.
What are empirical and molecular formulas?
Empirical formula: simplest whole number ratio of atoms in a compound.
Molecular formula: actual number and type of atoms in a molecule.
How can you calculate empirical and molecular formulas?
Use mass or percentage compositions and relative molecular mass.
What do the terms anhydrous and hydrated mean?
Anhydrous: no water of crystallization.
Hydrated: contains water of crystallization.
How can you determine the formula of a hydrated salt?
Through percentage or mass composition data.
How do you express concentration in mol dm⁻³ and g dm⁻³?
Concentration in mol dm⁻³: moles of solute per volume of solution in dm³.
Concentration in g dm⁻³: grams of solute per volume of solution in dm³.
What is the ideal gas equation?
pV = nRT, where p is pressure, V is volume, n is amount of substance, R is the gas constant, and T is temperature.
What is the significance of stoichiometric relationships?
They allow calculations based on the ratios of reactants and products in a chemical reaction.
How is percentage yield calculated?
(actual yield / theoretical yield) x 100.
What is atom economy?
A measure of the efficiency of a reaction in converting reactants into useful products, calculated as (molar mass of desired products / total molar mass of reactants) x 100.
Why is high atom economy beneficial?
It reduces waste and improves sustainability in chemical processes.
