SC9 Flashcards
(12 cards)
What is the molecular formula?
the actual number of atoms of each element in a compound
What is the emperical formula?
Shows the simplest whole number ratio or atoms or ions of each element in a compound
What is the relative formula mass
The relative formula mass of a substance is the sum of the relative atomic masses of all the atoms or ions in its formula
an oxide of phosphorus contains 3.49G of phosphorus and 4.51G of oxygen calculate the empirical formula of this phosphorus oxide.
Ar, O=16, P=31
P O
3.41/31=0.113 || 4.51/16=0.282
0.113/0.113=1 || 0.282/0.113=2.5
1x2=2 || 2.5 x2=5
Empirical formula is
P2O5
Fine molecular formula steps
Mr/EFM
1) Find the emperical formula mass(EFM)
2) Divide the Mr by the RFM to get a whole no
3) Multiply the EF by this whole number to get the molecular formula
What is concentration of a Solution
Amount of solute dissolved in a stated volume of solution
State the two ways to calculate concentration
1) Mass concentration (gdm^-3)
mass con= m(in g) / v (in dm^-3)
2) mole concentration(moldm^-3)
mol con= mol(in mol) / v (in dm^-3)
how to convert volume cm to dm
and vol dm to cm
divide by 1000
vice versa multiply by 1000
suggest the total mass of product in a closed and open sustem
in a closed system there is no loss of product so total mass of reactsnt = total mass of product
in an open system one of the products may escape as gas so there will be a loss of mass,
loss of mass = mass of gas which escaped
however rven in open system total mass of reactant is equal to mass in products
what is mole ratio
the amount of a substance which contains the arogadros constant number of particles
what is arogardos constant
it is the number of particles present in 1 mole of a substance
numerically the number is 6.023x10^23
how to calculate mole
mole= mass /Mr
