Amount Of Substance Flashcards
Acid + Base -> ?
Salt + water
Acid + carbonate-> ?
Salt + water + carbon dioxide
Ionic equation for neutralisation (acid and base)
H+(aq) + OH-(aq) -> H2O (l)
Ionic equation for neutralisation (acid and carbonate)
2H+(aq) + CO3 2-(aq) -> H2O (l) + CO2 (g)
Ionic equation for neutralisation (acid and hydrogencarbonate)
H+(aq) + HCO3-(aq) -> H2O (l) + CO2 (g)
Ionic equation for neutralisation (acid and ammonia)
H+(aq) + NH3(aq) -> NH4+(aq) compound
How does water dissolve ionic substances
There is a bond between the water molecules and ions that can be stronger than the actual ionic bonds in the lattice. So te ion is taken away.
Spectator ions
The ions that are not involved in a reaction involving ionic compounds dissolved in water.
Mass and moles formula
Moles = Mass(g) / Mr
Moles and concentration formula
No. of moles = conc(mol/dm3) X vol(dm3)
Ideal gas law
PV=nRT P(pa) V(m3) n(moles) R(8.31) T(K)
Assumptions made in the ideal gas law
Molecules/atoms: occupy negligible volume, exert no force on each other (all collisions are completely elastic), don’t react when they collide.
Limiting reagent
The reactant that is not in excess.
%yield formula
(mass of product/max theoretical mass) X 100
Atom economy equation
(mass of wanted product/total mass of products) X 100
Empirical formula
The simplest whole number ratio of the atoms of each element in a substance.
Finding the molecular formula from the empirical formula
Divide real Mr by the empirical Mr and multiply the numbers of each element in the empirical formula by this number.
What affects %yield?
If the reaction is reversible, if the product is lost when isolating it from the reaction mixture, unwanted reactions may occur.
How to prepare a stock solution
Record the mass of a clean dry weighing boat. Measure the approximate mass of the sample. Find the mass of the sample on a high precision balance. Wash the contents of the weighing boat into a volumetric flask (250cm^3) using deionised water and a clean funnel. Add more deionised water nearly up to the mark. Shake well to dissolve. Make to the mark using a dropping pipette and shake well.
Difference between atom economy and %yield
Atom economy tells us in theory how many atoms must be wasted in a reaction. The yield tells us about the practical efficiency of the process and how much product is lost due to its lack of efficiency.
What is a mole?
A quantity of a substance that contains the Avogadro number of particles (atoms, molecules, or ions)
How to carry out a titration
Pour some of the stock solution into a beaker to prevent the possibility of contamination of the rest of the solution. Use a pipette and pipette filler to accurately measure out a specific volume. Empty into a conical flask and add 3drops of methyl orange. Rinse some of the acid you will use through the tap of a burette and clamp it vertically to a stand. Fill it to near the 0 mark. Put the flask on a white tile under this and allow the acid through the tap until the solution turns permanently red. Record the amount of acid used. Repeat, adding acid slowly when near the previous amount used. Repeat until concordant results (0.1cm^3).
Which titres do you use for the mean?
Only the concordant ones.
Units of gas constant R
J/K/mol