Foundations In Chemistry 1 Flashcards
What is relative isotopic mass?
The mass of an isotope relative to 1/12th of the mass of an atom of Carbon-12.
What is an isotope?
Atoms of the same element with the same number of protons and different number of neutrons.
What is relative atomic mass?
The weighted mean mass of an atom of an element relative to 1/12th of the mass of an atom of Carbon-12.
How to conduct mass spectrometry?
- Sample placed in spectrometer
- Sample vaporised and then ionised to form positive ions.
- Ions are accelerated- heavier ions move more slowly and are deflected less. The ions of the isotope become separated.
- Ions are detected as a ration of mass:charge (m/z)
- Each ion reaching the detector adds to the signal, so greater the signal greater the abundance.
- Mass to charge ratio = m/z = relative mass of an ion/ relative charge on ion.
What is relative molecular mass?
The mean average mass of the formula units relative to 1/12 of the mass of a Carbon-12 atom
What is ‘amount of substance’ ?
A means of counting atoms, its unit is the mole
What is Avogadro’s constant?
6.02 x 10^23
The number of atoms per mole of Carbon-12.
What is the mole?
The amount of any substance containing as many particles as there are Carbon atoms in 12 grams of Carbon-12 ( 6.02 x 10^23 particles)
What is the molar mass?
The mass per mol of a substance in gmol^-1
What is the empirical formula?
The simplest whole number ratio of atoms of each element in a compound.
How would you carry out an experiment to determine the water of crystallisation in hydrated salts?
Step 1- weigh an empty crucible
Step 2- add the hydrated salt into the weighed crucible, weigh the crucible and the hydrated salts
Step 3- using a pipe-clay triangle, support the crucible containing the hydrates salt on a tripod, heat the crucible and contents gently for about one minute. Then heat it strongly for a further three minutes.
Step 4- leave the crucible to cool. Then weigh the crucible and anhydrous salts.
What happens when blue crystals of hydrated copper (II) sulfate is heated?
Bonds holding the water within the crystal are broken and that water is driven off, leaving behind white anhydrous copper II sulfate
How to calculate number of moles
Mass/ molar mass
What is the empirical formula
Simplest whole number ratio of atoms of each element in a compound
What is molecular formula
Shows the number and type of atoms present of each element present in a compound
What is water of crystallisation
Water molecules that form an essential part of the crystalline structure of a compound.
They have a dot formula.
For example; SnCl4.8H2O
The dot formula shows how many water molecules are in that compound
Determination of the water of crystallisation of copper sulfate?
- Weigh an empty crucible and record weight
- Place about 4 spatulas of copper sulfate in the crucible and record weight.
- Support the crucible with the hydrates salt on a pipe-clay triangle, on a tripod. Heat the crucible with a Bunsen burner gently for a minute, then heat strongly for a further three.
- Leave the crucible to cool, then weigh the new mass of the crucible and now anhydrous salt
Unit for concentration
Mol dm -3
Number of moles calculation (conc)
Concentration (mol dm-3) X volume (dm3)
What is molar gas volume
Volume of space in dm3 taken up by one mole of gas volume is 24dm3 mol-1
What is avogadros law?
Equal volumes of gases at the same temperature and pressure contain each numbers of moles
What is a standard solution?
A solution with a known concentration