Module 2 key information Flashcards
What is the relative mass of a proton, neutron and electron?
Proton= + 1 neutron= 1 electron= 1/1836
What is the charge of a proton, neutron and electron?
Proton= +1 neutron = 0 electron= -1
What is an isotope?
Atoms of the same element with different numbers of neutrons but the same number of protons.
So the same atomic number but a different mass number.
Do isotopes have the same properties?
They have similar chemical properties because of the same electronic configuration
They have slightly different physical properties because of the different masses
What is relative isotopic mass?
The mass of an isotope relative to 1/12th of the mass of an atom on carbon-12
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
What is relative molecular mass?
(Mr)= the sum of all atomic masses in the molecule
Used for simple molecules
What is relative formula mass?
sum of all atomic masses in the molecule
Used for compounds with giant structures
How to complete mass spec?
the sample is vaporized, ionised, accelerated, deflected, detected
What is mass spec used to find out?
relative isotopic masses and abundance
What is the nitrate ion?
NO3-
What is the sulphate ion?
SO4(2-)
What is the carbonate ion?
CO3(2-)
What is the hydroxide ion?
OH-
What is the ammonium ion?
NH4(+)
What is the zinc ion?
Zn2+
What is the silver ion?
Ag+
What is the charge on a tin or lead ion?
+2
How to balance a chemical equation?
1) balance metals
2) balance non-metals except oxygen and hydrogen
3) balance oxygen and hydrogen
What are the units for molar mass?
g mol-1
How to convert cm3 to dm3?
divide by 1000
How many cm3 is 1ml?
1cm3=1ml
How to convert cm3 to m3?
divide by 1000 then divide by 1000 again
What is the empirical formula?
The simplest whole-number ratio
What is the molecular formula?
the number and types of atoms of each element in a molecule
How to work out moles from mass?
mass= mr X mol
What is Avogadro’s constant?
The number of particles per mol
= 6.02 x 10(23)
How to work out the number of particles?
moles x Avogadro’s constant
How to work out the volume using molar gas volume?
Molar gas volume ( at rtp it is 24 in dm3) x mol
How to work out the moles using concentration?
Moles= concentration x volume
What is the ideal gas equation?
PV= nRT P= pressure in pascals V= volume in m3 n= moles R= gas constant (8.314) T= tempreture in Kelvin
How to convert degrees to kelvin?
+273
What does anhydrous mean?
Contains no water molecules in the structure
What does hydrated mean?
Contains water molecules in its crystalline structure
What is water crystallisation?
a number of water molecules present in a crystalline structure.
How to carry out the water of crystallization?
weight out the empty crucible
add the hydrates salt into the weighed crucible and then weigh again
pipe-clay triangle to heat gently then strongly
leave crucible to cool and then weigh anhydrous and crucible
What assumptions do we make when carrying out the water of crystallisation?
1) How do you know all the water has been extracted ( heat till mass is constant)
2) There may be further decomposition ( colour change)
How to calculate the formula of hydrated salt from percentage composition?
100%- percentage composition= % composition of the other molecule.
divide percentage by molar mass and compare the ratio
eg: 36%/18
How to calculate the formula of the hydrated salt from the mass composition?
the molar mass of the whole composition - the molar mass of the salt= molar mass of H20
the molar mass of water/ 18= ratio
Why gas syringe can be inaccurate?
1) gas can escape before you insert the bung
2) some gasses dissolve