Atoms And Reactions

Question 1

What is the relative atomic mass?

Answer 1

Weighted mean mass of an atom of an element compared to 1/12 of an atom of carbon 12

Question 2

What is the relative isotopic mass?

Answer 2

Mass of an atom of an isotope compared with 1/12 of and atom of carbon 12

Question 3

What is the relative molecular mass or relative formula mass?

Answer 3

The average mass of a molecule or formula unit compared to 1/12th of the mass of an atom of carbon 12

Question 4

What is the relative mass of protons, neutrons and electrons?

Answer 4

Proton and neutron - 1

Electron - 1/2000

Question 5

What is Avogadro’s constant?

Answer 5

6.02 x 10(23)

Question 6

What are the units for Molar Mass?

Answer 6

grams per mol - g mol-1

Question 7

What is the empirical formula ?

Answer 7

the smallest whole number ratio of atoms of each element in a compund

Question 8

What is the molecular formula?

Answer 8

the actual number of atoms of each type of element in a molecule

Question 9

What is an ionic equation?

Answer 9

only shows reacting particles

Question 10

What are the formulas of the molecular ions nitrate, carbonate, sulphate, hydroxide, ammonium, zinc ion and silver ion?

Answer 10

nitrate - NO3(-)
carbonate - CO3(-2)
sulphate - SO4(-2)
hydroxide - OH-
ammonium - NH4(+)
zinc ion - Zn(2+)
silver ion - Ag+

Question 11

Ionic compounds are made when …………..

Answer 11

positive and negative ions bond together

Question 12

salts are ………………

Answer 12

ionic compounds - lattice of positive and negative ions

Question 13

What is water of crystallisation?

Answer 13

hydrated if contains water of crystallisation - water in lattice
anhydrous if not

Question 14

acids are ……

Answer 14

proton donors

when mixed with water release H+ - produce H+ ions in an aqueous solution

Question 15

bases are ………..

Answer 15

proton acceptors

alkalis (soluble bases) produce OH- ions in an aqueous solution

Question 16

reactions between acid and water and bases and water are ……………..

Answer 16

reversible

Question 17

explain reactions with strong and weak bases and acids

Answer 17

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

Question 18

in a neutralisation reaction between acid and alkali ………….is produced

Answer 18

salt and water

Question 19

what are the four equations for acids with metal and metal compounds?

Answer 19

metal + acid = metal salt + hydrogen
metal oxide + acid = salt + water
metal hydroxide + acid = salt + water
metal carbonate + acid = metal salt + carbon dioxide + water

Question 20

what happens when ammonia reacts with acid?

Answer 20

ammonia + acid = ammonium salt

Question 21

how do you carry out a titration?

Answer 21

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

Question 22

what colours does methyl orange and phenolphthalein turn in acid and alkali?

Answer 22

methyl orange - yellow to red acid to alkali

phenolphthalein - pink to colourless acid to alkali

Question 23

what is an analyte?

Answer 23

the solution with an unknown concentration

Question 24

what is a standard solution? how is it made?

Answer 24

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

Question 25

what is reaction stoichiometry?

Answer 25

how many moles of one reactant react with how many moles of another reactant

Question 26

what are polyprotic acids?

Answer 26

donate more than one proton

Question 27

What is her theoretical yield?

Answer 27

the mass of product which should be made in a reaction if no chemicals are lost in the process

Question 28

What is the percentage yield?

Answer 28

the actual amount of product you collect as a percentage of the theoretical yield

Question 29

what is atom economy?

Answer 29

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

Question 30

what is an addition reaction?

Answer 30

the reactants combine to form a single product

atom econly = 100 no atoms are wasted

Question 31

what is a substitution reaction?

Answer 31

some atoms from one reactant are swapped with atoms from another reactant

Question 32

Why do chemical companies chose reactions with a high atom economy??

Answer 32

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

Question 33

what is the oxidation number of 
uncombined elements
identical elements
monatomic ion 
oxygen
hydrogen?

Answer 33

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

Question 34

ions ending in ate contain ……………..

Answer 34

oxygen and element

Question 35

What is a redox reaction?

Answer 35

reduction and oxidation happen simultaneously

Question 36

what is an oxidising agent?

Answer 36

accepts electrons and gets reduced

Question 37

what is an reducing agent?

Answer 37

donates electrons gets oxidised

Question 38

Metals are ……..when they react with acids

Answer 38

oxidised