4.3.2 Use of amount of substance in relation to masses of pure substances Flashcards
What is the unit used to measure chemical amounts?
Chemical amounts are measured in moles (mol).
How is the mass of one mole of a substance determined?
The mass of one mole of a substance in grams is numerically equal to its relative formula mass (Mr).
What is the Avogadro constant?
The Avogadro constant is 6.02×10^23 particles (atoms, molecules, or ions) per mole.
How does the concept of moles apply to different substances?
In one mole of carbon (C), the number of atoms is the same as the number of molecules in one mole of carbon dioxide (CO₂).
How can the masses of reactants and products be calculated?
Using balanced symbol equations.
How are chemical equations interpreted in terms of moles?
Example: Mg + 2HCl → MgCl₂ + H₂: 1 mole of magnesium reacts with 2 moles of hydrochloric acid to produce 1 mole of magnesium chloride and 1 mole of hydrogen gas.
How are equations balanced using moles?
Convert masses of reactants/products into moles. Use mole values to find simple whole number ratios.
What should you do if given the mass of reactants/products?
Convert the masses into moles and use them to balance the equation.
What is a limiting reactant?
The reactant that is completely used up in a reaction, limiting the amount of product formed.
What happens when one reactant is in excess?
The excess reactant ensures the other reactant is fully used, and the limiting reactant determines the maximum amount of product.
How does the limiting reactant affect the products?
It determines the amount of product that can be formed in moles or grams.
How is the concentration of a solution measured?
Concentration is measured as the mass of solute per volume of solution, e.g., grams per dm³.
How can the mass of a solute in a solution be calculated?
By using the known concentration and volume of the solution.
How are solute mass and solution volume related to concentration?
They are directly proportional: concentration increases with more solute or less volume.
