Stoichiometric Relationships Flashcards
What are the different changes of state
melting, freezing, vaporization (evaporation and boiling), condensation, sublimation and deposition.
What is a homogenous mixture
A homogeneous mixture is simply any mixture that is uniform in composition throughout. (components are combined)
what is a heterogenous mixture
A heterogeneous mixture is a mixture that composes of components that are physically separate
what do physical and chemical properties depend on
the way atoms combine
What is a mole?
a mole is the amount of substance that contains L particles of that substance.
The mass of one mole of any substance is known as the molar mass and has the symbol M.
What is the RAM
the relative atomic mass of an element (Ar) is the weighted mean of all the naturally occurring isotopes of the element relative to carbon-12.
Units: mol^-1 or Mr
-used to compare the masses of moles
What is avagadros constant for 1 mole
6.022 x10^23
what is avagadros law
THE EQUAL VOLUMES OF DIFFERENT GASES AT THE SAME TEMPERATURE AND PRESSURE CONTAIN THE SAME NUMBER OF MOLES
what does avagadros law explain
one mole of any gas will occupy the same volume at the same temperature and pressure. This is known as the molar volume of a gas.
what variables do you change for a fixed mass in gas
temperature (kinetic energy), volume(concentration of particles) and pressure( decrease in volume=increase in concentration=faster moving particles)
properties of chemical reactions
- new substances are formed
- bonds in the reactants are broken and bonds in the products are formed resulting in an energy change between the reacting system, and its surroundings
- there is a fixed relationship between the number of particles of reactants and products resulting in no overall change in mass- this is known as the stoichiometry of the reaction
State symbols
(s) -solid
(l) -liquid
(g) -gas
(ag) - in an aqueous solution
What 3 formulas for compounds exist
empirical, molecular, structural
what is the empirical formula
simplest whole number ratio of atoms of each element in a particle of substance
what is the molecular formula
shows the actual number of atoms of each element in a molecule of the substance. Can be obtained from the empirical formula if the molar mass of the compound is known.
what is the structural formula
-shows the arrangement of atoms and bonds within a molecule
properties of the solid state
- fixed shape
- fixed volume
- particles held together by intermolecular forces in a fixed position
- particles can vibrate about a fixed point but do not translational velocity
- as heat is supplied at a certain temperature the vibration is sufficient to overcome the attractive forces holding the solid together and the solid melts
properties of the liquid state
- fixed volume
- takes up shape of the container
- particles held closely together by intermolecular forces
- particles have translational velocity so diffusion can occur
- as heat is supplied the liquid particles move faster than others and escape from the surface of the liquid to form a vapour. Once the pressure of the vapour is equal to the pressure above the liquid; the liquid boils
properties of the gaseous state
- widely spaced particles that completely fill the container
- pressure of the gas due to gaseous particles colliding with the walls of the container
- intermolecular forces between particles negligible
- volume occupied by molecules themselves negligible compared with total volume of gas
- particles moving with rapid, random motion so diffusion can occur
units of molar mass (M)
g mol
what is a standard solution
a solution of known concentration, consisting of a solute and a solvent
what can can reactants sometimes be
limiting or excess (stoichiometry CHECK)
what is the experimental yield and the theoretical yield
experimental yield= substance produced in experiment
theoretical yield= substance on average theoretically produced
what is a mixture
when substances combine without chemical interaction
in what states does matter exist and what is it determined by
solids, liquids and gases:
determined by temperature, volume and pressure and the increasing kinetic energy of particles
what is kinetic energy
energy that a body possesses by virtue of being in motion
what is the kinetic theory of matter
the average kinetic energy of the particles is directly related to the temperature of the system
what are inter-particle forces
the state of matter at a given temperature and pressure determined by the strength of the forces between particles
Changes of state explanation
As the solid is heated, the vibrational energy of its particles increases and so the
temperature increases.
b–c This is the melting point. The vibrations are suf ciently energetic for the
molecules to move away from their xed positions and form liquid. Energy
added during this stage is used to break the inter-particle
forces, not to raise the kinetic energy, so the temperature
remains constant.
c–d As the liquid is heated, the particles gain kinetic energy and so
the temperature increases.
d–e This is the boiling point. There is now suf cient energy to
break all of the inter-particle forces and form gas. Note that
this state change needs more energy than melting, as all the
inter-particle forces must be broken. The temperature remains
constant as the kinetic energy does not increase during this
stage. Bubbles of gas are visible throughout the volume of the
liquid.
e–f As the gas is heated under pressure, the kinetic energy of its
particles continues to rise, and so does the temperature.
difference between Mr and Ar
Mr:relative formula mass: used to compare masses of compounds
Ar: relative molecular mass: used to compare masses of atoms
what is hydrated salt
compounds that contain a fixed ratio of of water molecules (water of crystallization)
what reactant determines the quantity of product
the limiting reactant
formula for percentage yield
experimental yield/theoretical yield x100
what does the atomic theory state
all matter is composed of atoms that can’t be created or destroyed, and are rearranged during chemical reactions
classification of matter into elements, compounds and mixtures
MATTER
- Mixture
a. homogenous
b. hetergenous - Pure Substance
a. element
b. compound
Boyle’s Law Formula (pressure and volume)
V1P1=V2P2
Charles Law Formula (temperature and volume)
V1/T2=V2/T2
Gay-Lussacs Formula (Temperature and pressure)
P1/T2=P2/T2
Combined Gas Formula (T, P and V)
p1V1/t1=p2v2/t2
what is the volume of 1 mole of any gas at STP
22.7 dm3
what is STP
standard temperature pressure
what is RTP
room temperature pressure
how do you convert celsius to kelvin +what are the units
C + 273= kPA
concentration formula
concentration= n(number of moles)/v(volume in dm3)
atom economy formula
total mass of desired products/total mass of all products x 100
