Atoms and reactions Flashcards
What is an isotope?
Atoms of the same element with different numbers of neutrons but the same number of protons and electrons and different masses
Relative isotopic mass
Mass of an isotope compared with 1/12th the mass of carbon-12
Relative atomic mass
Weighted mean mass of one atom of an element compared with 1/12th the mass of carbon-12
What is the purpose of mass spectrometry?
To determine relative isotopic masses and relative abundances of the isotope.
OR
Calculation of the relative atomic mass of an element from the relative abundances of its isotopes.
Charge of a nitrate ion
NO3 (1-)
Charge of a carbonate ion
CO3 (2-)
Charge of a sulphate ion
SO4 (2-)
Charge of a hydroxide ion
OH (1-)
Charge of an ammonium ion
NH4 (1+)
Charge of a zinc ion
Zn (2+)
Charge of a silver ion
Ag (1+)
What are spectator ions?
Ions present in a reaction mixture but do not participate in the reaction. They therefore have the same charge, formula and state and are present in the same quantity on each side of the equation.
What is a mole?
Unit for the amount of a substance.
What is Avogadro’s constant?
The number of particles per mole of a substance- 6.022x10^23.
Define empirical formula
The simplest whole number ratio of atoms of each element present in a compound.
Define molecular formula
The number and type of atoms of each element in a molecule.
Define anhydrous
Containing no water
Define hydrated
Containing water
Define water of crystallization
When water molecules form an essential part of the crystal structure of some compounds
Volume of one mole of any gas
24dm^3
Volume of gas equation
Volume= Moles x 24(000)
Ideal gas equation
pV= nRT p- pressure (Pascals) V- volume (m^3) 1m^3= 1000dm^3 n- number of moles R-8.314 (J/K/mol) T-temperature (Kelvin)
1atm
101325Pa
1 bar
100kPa= 100,000Pa
Define percentage yield
Percentage ratio of actual yield to the theoretical yield:
Experimental yield/Theoretical yield
Define atom economy.
What is the equation for atom economy?
A measure of the amount of starting materials that become useful products:
Mass of desired useful product/Total mass of all products
The higher the atom economy…
…the less waste is produced, making the process more economic and sustainable.
4 common acids
HCl, H2SO4, HNO3, CH3COOH
3 common alkalis
NaOH, KOH, NH3
Define acid
A substance which releases H+ ions in aqueous solution; proton donors.
Define base
What kinds of molecules can these be?
A substance which receives protons; a proton acceptor: metal oxides, metal hydroxides and ammonia
Define alkali
A soluble base which releases OH- ions in aqueous solution
Define salt
Any substance formed from the reaction between an acid and either a base, alkali or carbonate. The H+ion of the acid is replaced by a metal ion or NH4+
Define strong acids and weak acids
A strong acid is one that ionises fully in aqueous solution.
A weak acid is one that only partially dissociates in aqueous solution. Weak acids have a higher pH.
Define neutralisation reactions
Reactions in which acids and alkalis react quantitatively to form a salt, so that there are no H+ or OH- ions present in the product solution. Water is formed from these ions.
What is titration?
Briefly describe the process.
A technique where a solution of known concentration (Standard solution) is used to determine the concentration of another solution. The titrant is typically added via burette to a known quantity of the analyte until the reaction is complete often using an indicator to show this .
