Paper 1 - Topic 3, Quantitive Chemistry Flashcards
(30 cards)
What is the definition for atom economy
The measure of starting materials that end up as useful products
What is the definition for avogadro constant
The number of atoms, molecules or ions in a mole of a given substance
What is the definition for avogadros law
Equal amounts in moles of gases occupy the same volume under the same conditions of temperature and pressure
What is the definition for concentration
The amount of substance in a certain volumes of a solution
What is the definition for conservation of mass
The law of conservation of mass states that 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 definition for limiting reactant
The reactant that is completely used up since it limits the amount of products formed
What is the definition for mole
The mole is the unit for amount of substance, chemical amounts are measured in moles
What is the equation for calculating percentage by mass
mass of a component x 100
total mass of the mixture
What is the definition for percentage yield
The percentage ratio of the actual yield of product from a reaction compared with the theoretical yield
What is relative formula mass
The sum of the atomic masses of the atoms in the numbers shown in the formula, it is numerically equal to the mass of one mole of a substance in grams
What is the definition for theoretical yield
The maximum amount of product that could be produced from the given reactants, assuming a complete reaction takes place
What is the definition for thermal decomposition
The reaction that occurs when heat is applied to a compound causing it to break down into its different chemical constituents
What is uncertainty
- all measurements have a degree of uncertainty regardless of precision and accuracy
- uncertainty can be due to the limitations of the measuring equipment or due to the skill of the experimenter carrying out the experiments
Define relative atomic mass
The average mass of atoms in an element taking into account masses and abundance of its isotopes
How can you increase the precision of a result
Measure to more decimal places or use a more sensitive balance/apparatus
What is titration
A technique for finding the concentration of a solution by reacting a known volume of this solution with a solution of a known concentration
How do you conduct titration
- Rinse pipette with a solution of unknown concentration, use pipette to measure out the known volume of this solution
- Add an indicator
- Rinse the brunette with a solution of a known concentration, discard the liquid, use a brunette to gradually add the solution of a known concentration
- When indicator changes colour, volume added is recorded
- Important to get concordant volume results
- Use suitable equations to find concentration
Why is it not always possible to obtain the theoretical amount of product in a chemical reaction
- reaction may not complete because it is reversible
- some of the product could be lost when separated from the reaction mixture
- side reactions may occur, some of the reactants may react in a different way than expected
How do you work out the percentage yield
What happens if a reaction appears to involve a change in mass
Could be due to a reactant or product being a gas and the gas has been released into the atmosphere
If the relative mass of iron is 56 how much does 1 mole weigh
56g
What is the equation that links mass, moles and relative mass
Mass = Mr x moles
What equation links mass of a solute, volume and concentration
Mass (g) = concentration (g/dm3) x volume (dm3)
If there is a smaller volume or larger mass of solute, what is the concentration like
Higher
