Atoms And Reactions Flashcards
What is the relative atomic mass?
Weighted mean mass of an atom of an element compared to 1/12 of an atom of carbon 12
What is the relative isotopic mass?
Mass of an atom of an isotope compared with 1/12 of and atom of carbon 12
What is the relative molecular mass or relative formula mass?
The average mass of a molecule or formula unit compared to 1/12th of the mass of an atom of carbon 12
What is the relative mass of protons, neutrons and electrons?
Proton and neutron - 1
Electron - 1/2000
What is Avogadro’s constant?
6.02 x 10(23)
What are the units for Molar Mass?
grams per mol - g mol-1
What is the empirical formula ?
the smallest whole number ratio of atoms of each element in a compund
What is the molecular formula?
the actual number of atoms of each type of element in a molecule
What is an ionic equation?
only shows reacting particles
What are the formulas of the molecular ions nitrate, carbonate, sulphate, hydroxide, ammonium, zinc ion and silver ion?
nitrate - NO3(-) carbonate - CO3(-2) sulphate - SO4(-2) hydroxide - OH- ammonium - NH4(+) zinc ion - Zn(2+) silver ion - Ag+
Ionic compounds are made when …………..
positive and negative ions bond together
salts are ………………
ionic compounds - lattice of positive and negative ions
What is water of crystallisation?
hydrated if contains water of crystallisation - water in lattice
anhydrous if not
acids are ……
proton donors
when mixed with water release H+ - produce H+ ions in an aqueous solution
bases are ………..
proton acceptors
alkalis (soluble bases) produce OH- ions in an aqueous solution
reactions between acid and water and bases and water are ……………..
reversible
explain reactions with strong and weak bases and acids
strong acids - very little reverse, nearly alll the acid will dissociate in water releasing nearly all the h+ ions
strong bases - nearly all the base dissociates in water, lots of OH- ions are produced
weak acids - backward reaction favoured, only small amount dissociates, only few H+ produced
weak bases - ionise only slightly, small amount of bases dissociates, few OH- ions produced
in a neutralisation reaction between acid and alkali ………….is produced
salt and water
what are the four equations for acids with metal and metal compounds?
metal + acid = metal salt + hydrogen
metal oxide + acid = salt + water
metal hydroxide + acid = salt + water
metal carbonate + acid = metal salt + carbon dioxide + water
what happens when ammonia reacts with acid?
ammonia + acid = ammonium salt
how do you carry out a titration?
measure out some alkali using a pipette and put it in a flask with some indicator
fill a burette with acid
do a rough titration - idea of end point
do an accurate titration - read the bottom of the meniscus
work out the exact amount of acid used to neutralise the acid - final reading - initial reading = titre
what colours does methyl orange and phenolphthalein turn in acid and alkali?
methyl orange - yellow to red acid to alkali
phenolphthalein - pink to colourless acid to alkali
what is an analyte?
the solution with an unknown concentration
what is a standard solution? how is it made?
a solution with a precise known concentration
weigh the require mass of solid
transfer solid to a beaker - use some water to wash any solid bits into the beaker
add water to the beaker to completely dissolve the solid - use a glass rod to stir
transfer the solution to a volumetric flask - rinse the beaker and glass rod transferring the water to the flask
fill the flask to the graduation line with water
put the lid on and turn to mix
what is reaction stoichiometry?
how many moles of one reactant react with how many moles of another reactant
what are polyprotic acids?
donate more than one proton
What is her theoretical yield?
the mass of product which should be made in a reaction if no chemicals are lost in the process
What is the percentage yield?
the actual amount of product you collect as a percentage of the theoretical yield
what is atom economy?
a measure of the proportion of reactant atoms that become part of the desired product in the balanced chemical equations
atom economy = molecular mass of desired product/ sum of molecular masses of all products x 100
what is an addition reaction?
the reactants combine to form a single product
atom econly = 100 no atoms are wasted
what is a substitution reaction?
some atoms from one reactant are swapped with atoms from another reactant
Why do chemical companies chose reactions with a high atom economy??
environmental and economic benefits
at low atom economy - lots of waste, cost t separate desired product from waste, less sustainable - raw materials(limited supply) are wasted,
lower temperatures are cheaper and more environmentally friendly
renewable sources are better
what is the oxidation number of uncombined elements identical elements monatomic ion oxygen hydrogen?
uncombined elements = 0
identical elements = 0
monatomic ion = same as its charge
oxygen = -2 except in peroxides = -1 or O2 = 0
hydrogen = +1 except in hydroxides = -1 or H2 = 0
ions ending in ate contain ……………..
oxygen and element
What is a redox reaction?
reduction and oxidation happen simultaneously
what is an oxidising agent?
accepts electrons and gets reduced
what is an reducing agent?
donates electrons gets oxidised
Metals are ……..when they react with acids
oxidised
