Amount of Substance Flashcards
Equation to find the number of moles?
n = mass / mr
Moles = Mass / Mr
mass in g
One mole is equal to… (Avogadro’s Constant, L)
6.023 x 10^23
Grams (g) to Kilograms (Kg)?
Divide by 1000.
cm^3 to dm^3.
Divide by 1000.
dm^3 to m^3.
Divide by 1000.
cm^3 to m^3.
Divide by 1000000.
Equation to find the mass?
Mass = Moles x Mr Mass = n x Mr
Percentage Yield Equation?
% Yield = Actual Yield / Theoretical Yield x 100
Percentage Atom Economy Equation?
% Atom Economy = Mass of desired product / Total mass of reactants x 100
Standard pressure?
100kPa (1 atm)
Standard temperature?
273K (0 Degrees Celsius)
Gaseous Moles Equation?
n = v(cm^3) / 24000
or
n = v(dm^3) / 24
Calculating volumes of gases in equations? (Definition)
1 mole of any gas occupies 22.4dm^3 at standard temperature and pressure.
Molarity/Concentration Equation?
n = MV(cm^3) / 1000 Moles = Molarity x Volume / 1000 M = n x 1000 / V(cm^3) Molarity = Moles x 1000 / Volume
The Ideal Gas Equation?
pV = nRT p = pressure in Pa V = volume in m^3 n = number of moles R = the gas constant 8.31JK(-1) mol (-1) T = temperature in K
kPa to Pa?
Multiply by 1000.
Degree Celsius to Kelvin?
Add 273
Concentration/Molarity is measured in…
mol dm^3
State Symbol s is…
Solid.
State Symbol g is…
Gas.
State Symbol aq is…
Aqueous (solution in water).
What are Titrations used for?
Titrations are used to find out the concentration of an acid or an alkali.
State Symbol l is…
Liquid.
Titration needs… (4)
- A standard solution with an accurately known concentration.
- A graduated burette to deliver precise volumes of one of the solutions.
- A conical flask to hold a precise volume of the other solution, measured using a transfer pipette.
- An indicator.
What is a Titre?
The volume of titrant needed to react completely with the reagent in the flask.
What is Empirical Formula?
The empirical formula of a compound gives the simplest ratio of the number of atoms of each element in a molecule/entity.
What is Molecular Formula?
The molecular formula of a compound gives the actual number of atoms of each element in a molecule/entity.
What is Atom Economy?
Atom Economy is a measure of the proportion of reactant atoms that become part of the desired product in the balanced chemical equation.
What is Theoretical Yield?
The mass of product that should be formed in a chemical reaction.
Bromomethane is reacted with Sodium Hydroxide to make Methanol:
CH3Br + NaOH > CH3OH + NaBr
Calculate the atom economy of this reaction.
23.7%
Calculate the amount, in moles, of TiCl4 in 165g.
Moles = Mass / Mr n = 165 / 189.9 n = 0.87 moles
A sample of Magnesium Nitrate decomposed to produce 0.402 mol of gas. Calculate the volume, in dm^3, that this gas would occupy at 333K and 1.00 x 10^5. (The gas constant R = 8.31 JK(-1) mol (-1) )
pV = nRT p = 100000 Pa V = ? n = 0.402 mol R = 8.31 JK(-1) mol (-1) T = 333 K
100000 x V = 0.402 x 8.31 x 333 100000 x V = 1112.42646 1112.42646 / 100000 = V V = 0.0111 m^3 m^3 > dm^3 = Multiply by 1000. 0.0111 x 1000 = 11.1 11.1 dm^3
An oxide of Nitrogen contains 25.9% by mass of Nitrogen. Determine the empirical formula of this oxide.
N O
- 9 74.1
- 9/14 74.1/16
- 85 4.631
- 631 / 1.85 = 2.5 (x2)
2: 5
N2O5
Suggest one possible danger when a metal carbonate is reached with an acid in a sealed flask.
An explosion = Glass breaks.
A solution containing 0.732 mol of Ammonia was made up to 250cm^3 in a volumetric flask by adding water. Calculate the concentration of Ammonia in this final solution and state the appropriate units.
Molarity = Moles x 1000/V(cm^3)
M = 0.732 x 1000 / 250
M = 2.93
2.93 mol dm(-3)
The reaction of Magnesium Nitride, Mg3N2, with water produced Ammonia and Magnesium Hydroxide. Write an equation for this reaction.
Mg3N2 + 6H2O = 2NH3 + 3Mg(OH)2
The amount of substance that contains 6.022 x 10^23 particles is called…
A mole.
The definition of the Avogadro constant is…
The number of atoms in 12g of Carbon - 12.
Boyle’s Law?
The product of pressure and volume is a constant as long as the temperature remains constant.
Boyle’s Law Equation?
PV = constant.
Charles’ Law Equation?
V ~ T and V/T = constant.
Charles’ Law?
The volume is proportional to the temperature as long as the pressure remains constant.
Gay-Lussac’s Law Equation? (Constant volume law)
P ~ T and P/T = constant.
Combining these relationships gives us the equation:
PV/T = constant for a fixed mass of gas
Gay-Lussac’s Law? (Constant volume law)
The pressure is proportional to the temperature as long as the volume remains constant.
2 mol dm(-3) means…
There are 2 moles of solute per cubic decimetre of solution.
1 decimetre is…
10cm.
One cubic decimetre, 1dm^3 is…
1000cm^3.
What is ibuprofen?
A mild painkiller and anti-inflammatory drug.
