Chapter 3 Flashcards
How are chemicals measured?
1) mass
2) volume
What is one mole?
The amount of a substance that contains 6.02x10^23 particles
What is the Avogadro constant?
6.01x10²³, the number of particles in each mole of carbon-12
What is the mass of one mole of carbon, C?
12.0g
What is the mass of one mole of hydrogen, H?
1.0g
What is molar mass, M?
The mass per mole of a substance
What are the units of molar mass?
g mol^-1
amount, n =
mass, m / molar mass, M
What is a molecule?
Two or more atoms held together by covalent bonds
What is molecular formula?
The number of atoms of each element in a molecule
What is empirical formula?
The simplest whole-number ratio of atoms of each element in a compound
What is relative molecular mass, Mr?
The comparison of the mass of a molecule with the mass of an atom of carbon-12
What is relative formula mass?
The comparison of the mass of a formula unit with the mass of an atom of carbon-12
How do you calculate relative formula mass?
By adding together the relative atomic masses of the elements in the empirical formula
How do you calculate relative molecular mass?
By adding together relative molecular masses of the elements making up a molecule
What does it mean when crystals are hydrated?
Water molecules are part of their crystalline structure
What is water of crystallisation?
Water molecules that are bonded into a crystalline structure of a compound
What is the formula of the reaction where hydrated copper(II) sulfate is heated?
CuSO₄•5H₂O(s) → CuSO₄(s) + 5H₂O(l)
What would happen if there was no water in copper(II) sulfate?
1) the crystalline structure would be lost
2) a white powder would remain
What are the 2 assumptions made when determining that an experimental formula is accurate?
1) all of the water has been lost
2) no further decomposition
What does it mean when the hydrated and anhydrous forms have different colours?
You can be fairly sure when all of the water has been removed
How can you check that all water has been removed?
Heat to constant mass - repeatedly reheat until the mass of the residue no longer changes
How are liquids and gases measured?
By volume
How do you measure the mass of a solution or a gas?
Convert the volume into amount of substance, in moles to be able to count the particles present
What is 1cm³ in ml?
1ml
What is 1dm³ in cm³?
1000cm³
What is 1dm³ in ml?
1000ml
What is 1dm³ in l?
1l
n =
c x V
What is a standard solution?
A solution of known concentration
How are standard solutions prepared?
1) dissolving an exact mass of the solute in a solvent
2) making up the solution to an exact volume
What are the units for mass concentration?
gdm⁻³
What is the molar gas volume Vₘ?
The volume per mole of gas molecules at a stated temperature and pressure
What is RTP?
1) 20°C
2) 101kPa (1 atm) pressure
At RTP, what volume does 1 mole of gas molecules have?
24.0dm³ = 24000cm³
What is the molar gas volume at RTP?
24.0 dm³mol⁻¹
amount n (mol) =
volume V / molar gas volume Vₘ
When V is in dm³ n =
V(dm³) / 24.0
When V is in cm³ n =
V(cm³) / 24000
What are the assumption for the molecules making up an ideal gas?
1) random motion
2) elastic collisions
3) negligible size
4) no intermolecular forces
What is the ideal gas equation?
pV = nRT
pV =
nRT
What is the value of R in the ideal gas equation?
8.314Jmol⁻¹K⁻¹
What are the units of temperature in the ideal gas equation?
K
What is absolute zero?
-273°C
What are the units of pressure in the ideal gas equation?
Pa
What are the units of volume in the ideal gas equation?
m³
How do you convert from cm³ to m³?
x 10⁻⁶
How do you convert from dm³ to m³?
x 10⁻³
How do you convert from °C to K?
+273
How do you convert from KPa to Pa?
x 10³
What is the stoichiometry of a reaction?
The balancing numbers which give the ration of the amount, in moles, of each substance
What are balanced equations used to find?
1) the quantities of reactant required to prepare a required quantity of a product
2) the quantities of products that should be formed from certain quantities of reactants
What is an advantage of reactions with high atom economies?
1) produce a large proportion of desired products and few unwanted waste products
2) are important for sustainability as they make the best use of natural resources
What are the effects of improving atom economy?
1) makes industrial process more efficient
2) preserves raw materials
3) reduces waste
