1.4/1.5 The mole & ideal gas Flashcards
relative atomic mass
Relative atomic mass, A, is the weighted average mass of one atom of an element relative to the 1/12 the mass of an atom of carbon-12.
molar mass
The mass of a mole of a substance (g/mol)
Percentage Yield
The experimental yield as a percentage of the maximum theoretical yield (expt/theo x 100)
empirical formula
formula obtained by experiment, showing the simplest whole number ratio of atoms of each elements in a particle of a substance
molecular formula
the actual number of atoms of elements in a compound
concentration
amount of solutes per unit of volume of solutions
room temperature and pressure
One mol of any gas occupies 24000 cm3 (24L) at r.t.p (298K/25C and 1atm/100kpa)
Standard temperature and pressure
One mol of any gas occupies 22700 cm3 (22.7L) at s.t.p (273K/0celsius and 1atm/100kpa)
When is real gases similar to the ideal gas?
Real gases closely approximate ideal gases when they are at low pressure (increases distance) and high temperature
(more random motion). Overall, reduces effectiveness of intermolecular attractive forces.
pressure
particles colliding on the walls / boundaries of the container
Ideal gas
1.no volume
2. no intermolecualr foce except when they collids
3. Gas particles are in a state of continuous random motion
4. Collisions are perfectly elastic (no loss of kinetic energy)
5. Absolute temperature is proportional to Kinetic Energy of the particles
real gas
- volume
- intermolecular force
- attractive force between the particle and the wall
units for volume of gas
1000cm3=1dm3
100dm3=1m3
Boyles law
for fixed mass/moles of any gas at a constant temperature. its volume is inversely proportional to its pressure
Draw the graphs of Boyles law
Charles Law
for fixed mass/moles of any gas at a constant temperature. its volume is inversely proportional to its pressure
Draw the graph of Charles law
avogadros consant
The mole is the Sl unit of amount
of substance. One mole contains
exactly 6.022 x 1023 elementary entities. This number is the fixed numerical value of the Avogadro constant, NA.
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How do you convert grams to number of particles?
Relative formula mass
Relative formula mass, Mr, is the sum of the weighted average of the atoms of an element ina formula unit relative to 1/12 of an atoms o carbon12
mols formula
Calculating empirical formula
For empirical formula, first divide percentage mass or mass by RAM, then divide by the smallest one
Tip: Case 1: percentage composition given➟assume 100 then convert to grams
Describe the procedure for magnesium oxide experiment
1) Weigh the crucible with the lid (mass 1) and then the magnesium inside the crucible with the lid (mass 2).
2) heat the crucible until you see no further reaction. Oxygen has reacted with magnesium to make magnesium oxide
3)Turn off the Bunsen burner and allow the apparatus to cool.
4) Re-weigh the crucible with the lid containing the product (mass 3)
What are limitations to the magnesium oxide experiment
1) Soot
2) magnesium oxide & magnesium nitrate production
Combustion analysis
water of crystallization
fixed ratio of molecules of water, known as water of cristallyzation, within the crystalline structure of the compound. The water of cristallyzation can be driven off by heating, and the change in mass used to calculate the ratio of water molecules to the anhydrous salt.
limiting reagent
Step 1) Find number of mols of each reactant
step 2) Divide by the mol coefficient
step 3) Compare to determine the smallest number as the limiting reagent
Avogadro’s law
Equal volumes of all gases, when measured at the same temperature and
pressure (STP), containing an equal number of particles.
Gay Lussac law
For fixed mass/moles of any gas at a constant volume, its pressure is directly proportional to the temperature
The combined gas law
universal gas constant
Constant 𝑃𝑉/T is directly proportional to the fixed mass of the gas, or the
number of moles, n, introducing the constant, R
Pa x M3/molk = 8.31 Pa M^3 mol-1 K-1
kPa x dm^3 / molK = 8.31 kPa dm^3 mol-1k-1
Density ideal gas equation
molar mass ideal gas equation
ideal gas equation
-P: Pressure in kilopascals (kPa) In IB convert to Pa
- V: Volume decimeters cubed (dm3) In IB convert to m3
- n: Number of moles
- T: Temperature in kelvin
- R: 8.31 (Universal gas constant)
molar volume
The volume occupied by one mole of a substance (chemical element or chemical compound) at a given temperature and pressure
volume of a gas at STP
molar concentration equation
dilution equation
Adding solution method given concentration and volume of two solutions
calculate the new amount of mols by adding the number of moles from each individual solution, then find the new volume
Avogadros equation
Explain the graph
a. PV/nRT=1: The real gas behaves like ideal gas at low pressure and high temperature. The gases deviates at high pressure and low temperature.
b. PV/nRT>1: the volume of the gas particle is not negligible ➡ When pressure is higher than ideal gas, there are more collision with the wall as percentrage of volume of gas decreased
c. PV/nRP<1: there is attractive forces betwen the particle ➡ When the pressure is lower than ideal gas, there is attractive forces from other particles reducing the frequency of collision with the wall
Draw the charles graph
Draw Boyles graph
