Quantative Chemistry Flashcards
Explain the Law for the Conservation of Mass
Total mass of products in a reaction equal the total mass of the reactants
This is because no atoms are lost or made in a chemical reaction
Describe the difference between half and ionic equations
Half equations show what happens to one reactant in terms of electron gain/ loss
Whereas ionic equations show species involved in a reaction (and so omit spectator ions)
What is the Relative formula Mass?
The sum of the Relative Atomic Masses of all atoms in a compound
Why may an apparent change in mass be apparent in a chemical reaction?
When A product in a non-closed system reaction is a gas, which has mass, that is lost when the gas escapes
Or
When a gas in a non-closed system enters and solidifies during the reaction. The mass of the gas is not measured before hand, but is when solidified
What is a Mol?
A measure of particles contained in a substance
1 Mol= 6.03 * 10^23 particles
State the formula for a Mol
Mol= Mass/ RFM
What is the limiting “reactant”, and what is the “excess”?
A compound is created in fixed proportion. When one substance required in the reaction is used up, then the reaction can no longer continue. This substance is the Limiting Reactant.
The substances remaining, are said to be in excess
State the formula for Mols of Gas
Volume= Mol * 24dm^3
State the formula for the Concentration of a solution
Concentration = Mol/ Volume
What is titration used to measure?
Amount of acid that is needed to neutralise an alkaline
What indicator is used in Titration?
Phenolphthalein
3 Reasons why percentage yield is not 100%?
- Reversible reactions may convert some product back into reactants
- Produce lost during separation from reaction mixture- e.g. Spillages
State the formula for Percentage yield
Yield/ Max Theoretical Yield * 100
What is Atom economy?
A measure of the amount of reactant that ends up in useful product.
Why is a high Atom Economy desirable?
Sustainable development as less waste is produced
