- I - Chemistry // Module 2 // Foundations in Chemistry - I - Flashcards
Atoms, Compounds, Molecules and Equations. Amount of Substance. Acid-base and Redox Reactions. Electrons, bonding and Structure
How do you calculate the Mass Number (A)?
Number of protons + Number of neutrons
How do you calculate the number of Neutrons?
Mass Number (A) - Proton Number (Z)
What are the number of protons and electrons?
They are the same (Z)
What is Relative Atomic Mass (Ar)?
The weighted mean mass of an atom of an element relative to 1/12th of the mass of an atom of Carbon-12.
E.g Chlorine has two isotopes.
Chlorine-35 (75%) and Chlorine-37 (25%)
∴ Ar = 35.5
What is Relative Isotopic Mass?
The mass of an isotope relative to 1/12th of the mass of an atom of Carbon-12 and it is always an integer.
What is the order of how Mass Spectrometry works?
1) Sample is placed in mass spectrometer
2) Sample is vapourised and ionised to form positive ions
3) Ions are accelerated and deflected by an electromagnet. Heavier ions are more difficult to deflect than lighter ions so the ions of each isotope are separated.
4) Ions are detected on a mass spectrometer as mass-to-charge ratio m/z. Heavier ion will be less deflected so will have greater m/z.
5)Each ion reaching the detector adds to the signal, so the greater the abundance, the larger the signal. Size of the signal is used to determine the abundance of each isotope.
What is the shortened version of how Mass Spectrometry works?
V-Vaporised
I-Ionised
A-Accelerated
D-Deflected
D-Detected
How do you determine Relative Atomic Mass (RAM)?
Ar= (Relative Isotopic mass of Isotope 1 X Percent abundance of Isitope 1) + (Relative Isotopic mass of Isotope 2 X Percent abundance of Isotope 2) + … (if needed) /100
How do you calculate the amount of substance (mol)?
m=nXM
m- Mass (g)
n- Amount of a substance in Moles (mol)
M- Molar mass (g/mol)
What is water of crystallisation?
Water molecules that are bonded into a crystalline structure of a compound.
How can we remove all water from hydrous crystals?
Heat crystals until a constant mass is reached.
What colour is hydrous and anhydrous copper (II) sulphate?
Hydrous- Blue
Anhydrous- White
What are two assumptions that are made about the accuracy of an experimental formula?
Assumption 1- All of the water has been lost.
Assumption 2- There is no further decomposition when the crystal is heated.
How can you convert cm^3 to dm^3 ?
X1000
How can you convert dm^3 to cm^3 ?
Multiply by 1000
What is 1cm^3 in ml?
1cm^3 is 1ml
What is 1dm^3 in litres ?
1dm^3 is 1000cm^3 = 1000ml = 1litre
What is a solute?
A substance that dissolves in a solvent
What is a solvent?
A liquid which a solute dissolves into a solution
What is a solution?
Mixture formed by a solvent and solute.
What is the formula to calculate the number of moles using concentration?
n=cXV
n- number of moles
c- Concentration (mol dm^-3)
V- Volume in dm^3
What is the formula for molar volume?
V=nX24
V- Volume in dm^3
n- amount in moles
How do you convert degrees celsius into Kelvin?
+273
How do you convert cm^3 to m^3 ?
x10^-6
How do you convert dm^3 to m^3 ?
x10^-3
How do you convert kPa to Pa?
x1,000
What is the ideal gas equation?
pV=nRT
p- pressure (Pa)
V- Volume (m^3)
n- amount of gas molecules (mol)
R- ideal gas constant (8.31J mol^-1 K^-1)
T- Temperature (K)
What is the ideal gas constant?
8.31J mol^-1 K^-1
What is stoichiometry?
The ratio of the amount, in moles, of each substance in a chemical equation
