Module 2 - Amounts Of Substance Flashcards
What is the symbol for amount
of substance?
n
What is the unit used to
measure amount of
substance?
mol
What does the Avogadro
constant represent?
The number of atoms per mole of the
carbon-12 isotope
How to calculate the mass of 1
mole of the element?
Mass of 1 mole = relative atomic mass in
grams
How to calculate moles when
mass and molar mass are
given?
Moles (mol) = mass (g) / molar mass (g mol -1)
State Avogadro’s law
Under the same temperature and
pressure, one mole of any gas would
occupy the same volume.
How much volume does a gas
occupy, at room temperature
and pressure?
24 dm3
or 24000 cm3
Define molar gas volume
The volume per mole of gas molecules
Why do different gas particles
occupy the same volume?
The gas particles are very spread out,
hence individual differences has no
effect
How to calculate moles when
gas volume is given?
Moles (mol) = volume (dm3) / 24
Or
Moles (mol) = volume (cm3) / 24000
What are the ideal ways in
which gases behave? (5)
● They are in continuous motion
● No intermolecular forces experienced
● Exert pressure when they collide with each other or
container
● No kinetic energy is lost in the collisions
● When temperature increases, kinetic energy of gases also
increase
Write down the ideal gas
equation (in words and
symbols, including the units)
pV = nRT
Pressure (Pa) x volume (m3) = number of
moles (mol) x gas constant (8.314 J
mol-1)x temperature (K)
1 atmospheric pressure is
equal to how many pascal?
1 atm = 101325 Pa
0℃ is equal to how many
kelvin?
273 K
What does concentration of a
solution mean?
It is the amount of solute dissolved in 1
dm3
of solvent
How do you calculate moles
when concentration and
volume are given?
Moles (mol) = concentration (mol dm-3) x
volume (dm3
)
What is a standard solution?
A solution of known concentration
Write down the steps to
prepare a standard solution
- Weigh the solute using the weigh by difference method
- In a beaker dissolve the solute using the solvent
- Pour the solution into a volumetric flask
- Rinse the beaker using the solution and add it to the flask
- Add solvent to the flask carefully until it reaches the graduation
line - Mix the solution thoroughly to ensure complete mixing
What does the terms
concentrated and dilute
mean?
Concentrated - large amount of solute per dm3
of
solvent
Dilute - small amount of solute per dm3
of solvent
What is a species in a
chemical reaction?
Any particle that takes part in a reaction
What are the four common
state symbols?
- Solid (s)
- Liquid (l)
- Gaseous (g)
- Aqueous (aq)
What does the percentage
yield mean?
The efficiency of which reactants are
converted into products
What are the reasons for not
obtaining 100% yield? (5)
● Reaction may be at equilibrium
● The reactants may be impure
● Side reactions could happen
● Reactants or products may be left behind while
transferring
● Loss of products during separation and purification
How is percentage yield
calculated?
Percentage yield = (actual amount of
product (mol) / theoretical amount of
product (mol)) x 100
What does atom economy tell
us about?
The proportion of desired products
compared with all the products formed in
the reaction
How is atom economy
calculated?
Atom economy = (molecular mass of
desired product / sum of the molecular
masses of all products) x 100
Does 100% yield mean 100%
atom economy?
No, even if all the reactants are
converted into products, not all products
of the reaction will be the required
products
Which type of reaction has
100% atom economy?
Addition reactions (two or more reactants
are combined to form a product)
