C3 - Quantitative Chemistry Flashcards
Avogadros Constant
6.022 x10^23
Equation for moles
Mass
Moles= ———————
Mr
Equation for concentration
Moles/mass
Concentration = ——————
Volume
Cm cubed to dm cubed
Divide by 1000
How,to calculate percentage yield
Actual yield
Percentage yield = ———————————————————- X 100
Theoretical yield
How to calculate atom economy
RAM of desired product
Atom economy = ———————————————— x 100
total RAM of reactants
What is the volume of 1 mole of any gas at room temperature?
24 dm3
How to calculate the volume of a gas
Amount In moles × molar volume (24)
Number of moles x 24 = ….
Volume (dm3)
What does conservation of mass mean
no atoms are lost or made during a chemical reaction so the mass of the products equals the mass of the reactants.
What is the relative formula mass of a substance? (Mr)
The sum of the relative atomic masses of the atoms in a given formula
What is uncertainty
For a thermometer with a mark at every 1.0°C, the uncertainty is ± 0.5°C. The range of possible answers
What are moles and what is the unit for them?
Chemical amounts are measured in moles. The symbol for the unit mole is mol.
How to calculate the masses of substances in a balanced symbol equation
mass = relative formula mass × amount
Eg. O2 = 16 * 2
What is the limiting reagent in a chemical reaction
The reactant that is completely used up is called the limiting reactant because it limits the amount of products that can be made
How to calculate the relative atomic mass of an atom
- Identify isotopes present in the mixture or environment, and the abundance of each isotope of the element.
- Identify the mass number. For each isotope of the element.
- Do abundance times mass number for 1 isotope. Add the abundance times the mass number of the other isotope and divide by total % abundance (usually 100)
How can the concentration of a solution be changed (2 ways)
concentration can be increased by dissolving more solute in a given volume of solution - this increases the mass of the solute
concentration can be increased by allowing some of the solvent to evaporate - this decreases the volume of the solution
What is atom economy
measure of the amount of starting materials that end up as useful products.
What is the percentage yield?
A measure of how much product is actually made
explain how the concentration of a solution in mol/dm3 is related to the mass of the solute and the volume of the solution
The higher the mass of the solute in comparison to the volume of the solution, the higher the concentration
