Module 2 - [ch2,3,4] (foundations in chemistry) Flashcards
atoms, ions and compounds amount of substance acids and redox
Hydrochloric acid
HCl
Sulfuric acid
H₂SO₄
Nitric acid
HNO₃
ethanoic acid
CH₃COOH
bases
metal/alkali oxides
metal hydroxides
metal carbonates
ammonia
what makes a chemical a base
can neutralise an acid to form a salt
proton acceptor
what is an alkali
a base that dissolves in water
group 1 metal hydroxides
in solution they release hydroxide ion (OH~)
gain and loss of oxygen
in terms of hydrogen too
gain - oxidation - removal of hydrogen
loss - reduction - gain of hydrogen
what is a redox reaction
a reaction in which both oxidation and reduction occurs
what are spectator ions
ions that do not change during a reaction
define oxidation in terms of electron transfer and oxidation number
loss of electrons
increase in oxidation number
define reduction in terms of electron transfer and oxidation number
gain of electrons
decrease in oxidation number
oxidising agent
the chemical accepting the electrons
is reduced
reducing agent
chemical that is donating the electrons
what do oxidation numbers tell you
how electrons are lost or gained in a reaction
what has oxidation number 0
pure elements
what is the oxidation number of fluorine
-1
what is the oxidation number of oxygen
-2
EXCEPT
in peroxides
-1
when reacted with fluorine
+2
why is the oxidation number of oxygen bonded to fluorine +2
fluorine is electronegative enough to remove electrons from the oxygen
what is the oxidation number of the halogens
-1
can be positive if bonded to oxygen or fluorine
what is the oxidation number of hydrogen
+1
EXCEPT in metal hydrides
-1
when an acid is added to water which ion is released into solution
H+
(proton)
define acid
proton donor
what is a strong acid
fully dissociates in aqueous solution
releases all its H+ ions into solution
which base is used to treat acid indigestion
magnesium hydroxide
MgOH
what are amphoteric substances
substances that can act as acids ands bases
acid + carbonate ->
salt, Carbon dioxide , water
what is a salt
the product of a reaction in which the H~ ions from the acid are replaced by metal or ammonium ions
metal oxide + acid ->
salt , water
acid + alkali ->
salt , water
metal + acid ->
salt , hydrogen
ammonia(aq) + acid ->
ammonium salt
what are hydrated crystals
crystalline structure containing water
what are anhydrous crystals
crystalline structure containing no water
how is water of crystallisation represented
dot formula
method to perform a titration
use a pipette to measure volume of solution
add indicator
swirl ( use a white tile to clearly see end-point )
add acid into burette
record initial volume
slowly add
record volume leftover in burette when end point has been reached
repeat for concordant results
name indicators
methyl orange (orange - red)
phenolphthalein pink ( clear - pink )
what is the colour of methyl orange as an indicator
acid - red
base - yellow
end point - orange
how do we indicate an element has more than one stable oxidation number
roman numerals
what does the avogadro constant represent
number of atoms in 12g of carbon-12
how can you calculate the mass of 1 mole of an element
relative atomic mass in grams
e.g
1 mole of carbon-12 has mass 12g
moles {}
give unit too
moles = mass/Mr
mol
state avogadro’s law
under the same temperature and pressure one mole of any gas would occupy the same volume
what volume does 1 mole of a gas occupy under room temperature and pressure
24 dm^3
24000 cm^3
define molar gas volume
the volume per mole of gas molecules
moles{}
gas
moles = volume / 24
(dm^3)
what are the ideal ways in which a gas behaves
random movement
continuous motion
no intermolecular forces experienced
exert pressure when they collide with each other
no kinetic energy lost in collision
when temp increase, kinetic energies of gases increases
ideal gas equation {}
pV = nRT
pressurevolume = molesideal gas constant*Temperature
pa * m^3 = mol * Jmol^-1 * K
1atm = how many pascals
101 kPa
converting from degrees to kelvin?
+273
what does concentration of a solution mean
amount of solute dissolved in 1dm^3 of solvent
moles{}
conc
n = CV
moles = concentration * volume
mol = moldm^-3 * m^3
what is a standard solution
a solution of known concentration
what are the steps to preparing a standard solution
weigh the solute
dissolve solute using distilled water
pour solution into a volumetric flask
last traces rinsed and poured in
filled to graduation line
flask inverted to ensure solution is mixed thoroughly
concentrated
dilute
large amount of solute per dm^3 of solvent
small amount of solute per dm^3 of solvent
what is a species in a chemical reaction
any particle that takes part in a reaction
what does percentage yield mean
the efficiency to which reactants become products
why is percentage yield never 100%
reaction may be at equilibrium
the reactants may be impure
side reactions may occur
reactant or product may be left behind when transferring
loss of products during separation and purification
percentage yield{}
(actual yield / theoretical yield )* 100
what is atom economy
the proportion of products which was desired
atom economy {}
( mrdesired product / mr total products ) * 100
Describe what you would see when magnesium reacts with an excess of sulfuric acid [2]
Mg/solid dissolves
bubbles (hydrogen gas produced)
what is meant by the term mole [1]
Amount of substance that has the same number of
particles as there are atoms in 12 g of 12C
common use for NaClO [1]
bleach disinfectant
A student prepares a solution of calcium nitrate by reacting dilute nitric acid, HNO3, with the base calcium hydroxide, Ca(OH)2.
Why is calcium nitrate an example of a salt? [1]
The H+ ion in an (nitric) acid has been replaced by a metal ion
Explain how the hydroxide ion in aqueous calcium hydroxide acts as a base when it neutralises dilute nitric acid. [1]
Accepts a proton OR accepts H+
What term is given to the ‘*x H2O’ part of the formula? [1]
water of crystallisation
Explain what is meant by the term salt [1]
when the H+ in an acid is replaced by a metal ion
Define an acid. [1]
a proton donor
Chewing chalk has been used for many years to combat excess stomach acid and indigestion tablets often contain calcium carbonate, CaCO3. Suggest, with the aid of an
equation, how these tablets work. [2]
CaCO3 + HCl -> CaCl2 + H20 + CO2
calcium carbonate neutralises the acid
Describe and explain the trend, down the group, in the reactivity of the Group 2 elements with water. [5]
reactivity increases down the group
atomic radii increases
more electron shielding
nuclear attraction decreases
electron more easily lost
Define the term empirical formula. [1]
simplest whole number ratio of atoms
Using aqueous silver nitrate, it is sometimes difficult to distinguish between chloride, bromide and iodide ions.
How can aqueous ammonia be used to distinguish between these three ions? [3]
AgCl dissolves in conc NH3 (aq)
AgBr partially soluble in NH3 (aq)
AgI insoluble in NH3 (aq)
Explain what is meant by the term molecular formula. [1]
Number AND type of atoms making up a 1
molecule
Define the term relative isotopic mass [2]
the mass of an isotope relative to 1/12th
the mass of a carbon-12 atom
State what is meant by the term isotopes [1]
atoms of an element with the same number of protons but different number of neutrons
why do isotopes have similar chemical properties [1]
same number of electrons in the outer shell
Define the term relative atomic mass. [3]
weighted mean mass of an atom relative to 1/12th the mass of an atom of carbon-12
why would you repeat a titration multiple times
for concordant results (within 0.1cm^3 of each other
so you can then reject inaccurate titres
