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A Level Unit 2 - Quantitative Chemistry
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Terms in this set (39)
What is the relative atomic mass of an atom?
The weighted average mass of an atom of an element, taking into account its naturally occurring isotopes, relative to 1/12 the relative atomic mass of an atom of carbon-12
What is the relative molecular mass of a molecule?
The mass of a molecule compared to 1/12 the relative atomic mass of an atom of carbon-12
What is the relative atomic mass of X?
Relative mass of X taken from the A Level data sheet
What is the relative molecular mass of X?
Sum of relative atomic masses of all constituent atoms taken from the A Level data sheet
What is a mole?
A specific number of particles
What is the Avogadro Constant?
The number of things in a mole, 6.022x10²³
How many X particles are in Y moles of Z?
(number of X in Z) x (Y) x (6.022x10²³)
How are the number of moles of a substance established from its mass?
Moles = mass/Mr
How many moles are in Xg of Y?
X/Mr of Y
What is the mass of X moles of Y?
X x Mr of Y
X moles of a substance has a mass of Y. What is its Mr?
Y/X
Calculate the yield of a given reaction which results in Xg of product having started with Yg of reactant
Molar ratio from balanced equation, actual mass/expected mass x 100
A given reaction has a yield of Y% and Xg of product formed. What mass of reactant was used?
Divide X by Y and use molar ratio to calculate mass of reactant
What standard units are used for concentration of a solution?
moldm⁻³
How are cm³ converted to dm³?
Divide by 1000
X moles of a substance is dissolved in Yzm³ of water. What is its concentration?
After converting to dm³ X/Y
How many moles are in Abm³ of Cmolbdm⁻³ solution?
After proper conversions, AxC
What mass of X must be added to Ydm³ of solution to make a Zmoldm⁻³ solution?
Y x Z and multiply by Mr of X
What volume of water must be added to Xcm³ of Ymoldm⁻³ solution to turn it into a Zmoldm⁻3 solution?
calculate moles in Y. Calculate volume required to make it Z. Subtract X from answer.
What are concordant titres?
Titres within 0.1cm³ of each other
What colour is phenolphthalein in acid and alkali?
Colourless in acid, purple in alkali
Calculate the concentration of an unknown acid/alkali from titration with an unknown alkali/acid
Establish molar ratios, establish number of moles of known solution, establish moles of unknown solution needed, calculate concentration from vol of unknown
State the ideal gas equation
PV = nRT
Give the units for P, V and T
P in pascals, V in m³, T in kelvin
Rearrange the ideal gas equation for P, V, n, R and T
...
What does R stand for?
The gas constant, 8.31JK⁻¹mol⁻¹
Calculate the X of a gas at...
Rearrange, convert to proper units and calculate
A gas is at P ___, V___ and T___ with a mass of Xg. Calculate its Mr.
Use n = PV/RT to calculate moles then X/moles to calculate Mr
What is the empirical formula of a substance?
The formula that represents the simplest whole number ratio of the atoms of each element present in the compound.
A substance is composed of Xg of A, Yg of B and Zg of C. Establish its empirical formula.
Divide masses by Ar, convert to whole number ratio, apply to formula
What is the molecular formula?
The actual number of atoms of each element in one molecule of a compound
What is the formula of a named ionic compound?
Use the charges to work out how many of each ion are necessary to result in no net charge
What is an ionic equation?
A simplified equation showing the ions present in a reaction
What is a spectator ion?
An ion that does not take part in a reaction
Which substances produce ions in ionic equations?
Aqueous solutions of ionic compounds
Write an ionic equation for a given reaction
Correct identification of ions produced and removal of spectator ions
What is the atom economy of a reaction?
A ratio of the mass of desired product to the mass of all products
How is atom economy calculated?
(Mr or mass of desired product/Mr or mass of all products) x 100
Calculate the atom economy for a given reaction and a given desired product
(Mr or mass of desired product/Mr or mass of all products) x 100
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