Module 2 : Section 1 Flashcards
Describe the structure of the atom
Orbitals: Hold electrons in place
Nucleus: Where you find protons and neutrons.
Contains most of the mass.
Give the relative mass and relative charge of protons, neutrons and electrons.
Protons: Mass = 1 Charge = +1 Neutrons: Mass = 1 Charge = 0 Electrons: Mass = 1/2000 Charge = -1
What are isotopes?
Atoms of the same element with different numbers of neutrons.
Define relative atomic mass.
Mean mass of an atom of an element, relative to 1/12th the mass of Carbon-12.
Define isotopic mass.
Mass of an atom of an isotope of an element, relative tp 1/12th the mass of Carbon-12.
How do you calculate the isotopic abundance of:
B-10 = 20%
B-11 = 80%
100
On a mass spectrum, what does the y axis and x axis show?
Y axis = Abundance of ions. Height of each peak gives you the relative isotopic abundance.
X axis = mass/charge. Can assume it is the relative isotopic mass.
How would you calculate the relative atomic mass using data from a mass spectrum?
Multiply each relative isotopic mass by its relative isotopic abundance and add up the results. (X-axis value multiplied by its height)
Divide by the sum of the isotopic abundances (sum of the heights of the peaks)
Give the equation linking mols, molar mass and mass.
mols = mass / molar mass
Give the equation linking mols, volume and molar gas volume (24dm^3)
mols = volume/24 (dm^3) mols = volume/24000 (cm^3)
What is the ideal gas equation and what does it allow you to calculate?
pV = nRT allows you to calculate no of mols at any temperature or pressure. p = pressure (Pa) V = volume (m^3) 1cm^3 = 1x10^-6 m^3 1dm^3 = 1x10^-3 m^3 n = no. of mols R = 8.314 T = temperature (k) --> K= Degrees celsius + 273
What is the empirical formula?
Smallest ratio of atoms of each element in a compound.
ALWAYS MEASURED IN MOLS
What is molecular formula?
Actual no. of atoms of each element in a molecule.
How are ions formed?
Ions are formed when electrons are transferred from one atom to another.
Give the formula of the following molecular ions:
- NItrate
- Carbonate
- Sulfate
- Hydroxide
- Ammonium
- Zinc ion
- Silver ion
- NItrate = NO3 ^1-
- Carbonate = CO3 ^ 2-
- Sulfate = SO4 ^2-
- Hydroxide = OH ^1-
- Ammonium = NH4 ^1+
- Zinc ion = Zn ^2+
- Silver ion = Ag ^1+
What are salts?
Salts are ionic compounds.
Solid salts have a lattice of +ve and -ve ions.
What does a hydrated salt tell you?
It has waters of crystallisation attached to it.
What is an anhydrous salt?
A salt that does not contain waters of crystallisation.
How do you calculate the number of waters of crystallisation and formula of a hydrated salt.
- Find mols of water lost.
- Find mols of anhydrous salt.
- Calculate ratio of mols in anhydrous salt to mols of water in the form 1:n
?What is the main difference between acids and bases
Acids are proton (H+) donors
Bases are proton (H+) acceptors.
Give the name and formula of 4 common acids.
Hydrochloric acid HCl
Sulfuric acid H2SO4
Nitric acid HNO3
Ethanoic acid CH3COOH
Give the name and formula of 3 common bases.
Sodium Hydroxide NaOH
Potassium Hydroxide KOH
Ammonia NH3
When acids and bases react, how is water formed?
H+ ions released by the acid and OH- ions released by the base combine to form
OH- + H+ —> H20
When acids and bases react, how is the salt formed?
When the H+ ions in the acid are replaced by metal ions or ammonium ions from the alkali
HCl + KOH —> KCl + H2O
Describe the set up of equipment for performing a titration.
Measure out the alkali in a pipette to the line.
Let the alkali drop down into the conical flask and add an indicator.
Put the conical flask underneath a burette containing the acid, which allows you to add the acid drop by drop.
Describe the procedure of doing a titration.
- First do a rough titration, to get an idea of the end point.
- Do an accurate titration, run the acid within 2cm^3 of the endpoint, then add the acid dropwise (drop by drop)
- Calculate the titre ( final reading - initial reading)
- Repeat the titration and calculate a mean, ignoring any anomalous results.
- Remember to wash out the conical flask, to remove any acid or alkali.
How can you make a titration accurate?
When taking a reading from a burette, you should read from the bottom of the meniscus.
What is an analyte?
Solution of unknown concentration.
What is a standard solution?
Solution with a known concentration. Made by dissolving a known amount of solid in a known amount of water.
How do you make up a standard solution?
- Using a precise balance, weigh out the required mass of solid.
- Transfer to a beaker. Use distilled water to wash and bits of solid from the watch glass.
- Add water to completely dissolve the solid. Use a glass rod to stir the solution.
- Once dissolved, transfer into a volumetric flask.
- Fill volumetric flask up to graduation line.
- Put lid on the flask and turn in over to thoroughly mix it.
Give the equation linking mols, concentration and volume.
mols = conc x vol
Give the equation for % yield.
Actual yield / theoretical yield x 100
MOLS
Give the equation for Atom Economy.
Mr of desired product / Mr of all products x 100
Give an example of a reaction which has a 100% Atom economy.
Addition reaction, as only 1 product is made.
C2H4 + H2 —> C2H6
What does % yield tell you?
It tells you how wasteful the process is.
What does Atom Economy tell you?
Tells you the sustainability of reactions.
What is the oxidation number of Oxygen?
-2
What is the oxidation number of Hydrogen?
+1
What is oxidation?
Loss of electrons
What is reduction?
Gain of electrons.
What do oxidising agents do?
They accept electrons and get reduced.
What do reducing agents do?
They donate electrons and get oxidised.
