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CHEMICAL FORMULA AND EQUATIONS (Relative Atomic Mass (RAM) (formula (The…
CHEMICAL FORMULA AND EQUATIONS
Relative Atomic Mass (RAM)
no unit
carbon atom is used as standard because it is stable and easier to handle compare to hydrogen
To determine the mass of single atom is to compare its mass to the mass of another atom of an element that is used as a standard
formula
The average mass of one atom of the element / 1/12 x The m ass of atom of carbon
Percentage composition of element
Total RAM of the element of the compound / RMM of compound x 100
Chemical Equation
Chemical Formula
Empirical Formula
.the simplest whole number ratio of atoms of each elements in a com[pound
experiment
Magnesium oxide or reactive metal
steps
The crucible ,lid and magnesium is weigh again.
set up aparatus
magnesium is coiled and placed into in the crucible
2.clean magnesium ribbon with sand paper
The crucible is heated strongly without lid , when magnesium start burn , cover the crucible with lid
1.record the mass of lid an crucible
the lid is lift from time to time using tongs.
when magnesium stop burning, remove lid and continue heating for 2 minutes
9.cool it down at room temperature
weigh them again and record
repeat the process of heating , cooling and weighing until obtain constant mass
2Mg + O2-→ 2MgO
copper oxide or non-reactive metal
Cuo + H2 → Cu + H2O
Precaution steps
H2 must continues flowing through experiment
to prevent hot copper react with O2 again
allow H2 pass through for 5 min- 10 min
ensure combustion tube filled with H2
repeat the heating, cooling and weighing process
to ensure whole copper oxide has changed into pure copper
Hydrogen must pass through anhydrous chloride
absorb water vapour to dry hydrogen gas
Molecular Formula
a formula that shows the actual number of atoms of each element that are present molecules of the compound
Molecular formula = (empirical formula)n, n is an integer
MOLE CONCEPT
Number of particle
to describe the number of atoms , molecules and ions
molar volume of a gas
molar mass
the mass of one mole of any substances
