C3 Flashcards
Metals are represented in equations by what type of formula?
Empirical formula
Ionic compounds are represented in equations by what type of formula?
Empirical formula
Simple covalent molecules are represented in equations by what type of formula?
Molecular formula
What is the formula for carbon dioxide?
CO2
Bromine is a halogen
What is the formula for bromine?
Br2
What is the formula for nitrogen?
N2
What is the formula for oxygen?
O2
What is the formula for sulfur?
S
Potassium is a metal
What is the formula for potassium?
K
Aluminium is a metal
What is the formula for aluminium?
Al
What is the formula for sodium chloride?
NaCl
What is the formula for magnesium bromide?
MgBr2
What is the formula for lithium oxide?
Li2O
Phosphorus exists as simple molecules
What is the formula for phosphorus?
P4
Iodine is in group 7
What is the formula of an iodide ion?
I-
Chlorine is in group 7
What is the formula of a chloride ion?
Cl-
Sulfur is in group 6
What is the formula of a sulfide ion?
S2-
Oxygen is in group 6
What is the formula of an oxide ion?
O2-
Nitrogen is in group 5
What is the formula of a nitride ion?
N3-
Sulfate is a complex ion
What is the formula of a sulfate ion?
SO42-
Nitrate is a complex ion
What is the formula of a nitrate ion?
NO3-
Carbonate is a complex ion
What is the formula of a carbonate ion?
CO32-
Calcium is in group 2
What is the formula of a calcium ion?
Ca2+
What is the formula for methane?
CH4
What is the formula for sulfur dioxide?
SO2
What is the formula for sulfur trioxide?
SO3
What is the formula for carbon monoxide?
CO
What is the formula for silicon dioxide?
SiO2
What is the formula for potassium nitrate?
KNO3
What is the formula for lithium carbonate?
Li2CO3
What is the formula for iron(III) oxide
Fe2O3
What is the formula for a copper(II) ion?
Cu2+
What is the formula for a silver ion?
Ag+
What is the formula of sodium sulfate?
Na2SO4
In terms of structure, how do the group 7 elements exist?
Diatomic molecules
In terms of structure, how do the group 0 elements exist?
Monatomic gases
What is the half equation for sodium ions being produced from sodium?
Na –> Na+ + e-
What is the half equation for magnesium ions being produced from magnesium?
Mg –> Mg2+ + 2e-
What is the half equation for magnesium ions being produced from aluminium?
Al –> Al3+ + 3e-
What is the half equation for oxide ions being produced from oxygen?
O2 + 4e- –> 2O2-
What is the half equation for bromide ions being produced from bromine?
Br2 + 2e- –> 2Br-
What does Avogadro’s constant tell us?
The number of entities in one mole
What is the S.I. unit of measurement of amount of substance?
The mole (mol)
What is the value of Avogadro’s constant (including units)?
6.02 x 1023 /mol
How many moles of hydrogen atoms are contained in 3 mol of water molecules?
6 mol
What is meant by molar mass?
The mass of 1 mole of a substance
What are the units for molar mass?
g/mol
What is the molar mass of methane?
Ar of carbon = 12.0
Ar of hydrogen = 1.0
16 g/mol
What is an exothermic reaction?
A reaction where energy is transferred (given out) to the surroundings
What is an endothermic reaction?
A reaction where energy is transferred (taken in) from the surroundings
What happens to the temperature when an exothermic reaction takes place
The temperature increases
What happens to the temperature when an endothermic reaction takes place?
The temperature decreases
Are combustion reactions exothermic or endothermic?
Exothermic
What is the definition of bond energy?
The energy required to break 1 mole of a particular bond
Is bond breaking exothermic or endothermic?
Endothermic
Is bond making exothermic or endothermic?
Exothermic
What sort of reaction is this?
Endothermic
What sort of reaction is this?
Exothermic
Which arrow represents the overall energy change?
Arrow A
Which arrow represents the activation energy?
Arrow C
Define oxidation in terms of the transfer of oxygen
Gain of oxygen by a substance
Define reduction in terms of the transfer of oxygen
Loss of oxygen by a substance
Define oxidation in terms of electrons
Oxidation is a loss of electrons
Define reduction in terms of electrons
Reduction is a gain of electrons
What is a redox reaction?
A reaction where both oxidation and reduction happen at the same time
Oxidation or reduction?
Al –> Al3+ + 3e-
Oxidation
Oxidation or reduction?
Fe3+ + 3e- –> Fe
Reduction
What happens to an oxidising agent during a redox reaction?
It gets reduced
What happens to a reducing agent during a redox reaction?
It gets oxidised
Which species is being oxidised?
Mg(s) + CuO(s) –> MgO(s) + Cu(s)
Magnesium
Which species is the oxidising agent?
Mg(s) + CuO(s) –> MgO(s) + Cu(s)
Copper oxide
What is an acid?
A substance which releases H+ ions when dissolved in water
What is a base?
A substance which can neutralise acids
What is an alkali?
A base which is soluble in water
What is the pH of an acidic solution?
Less than 7
What is the pH of an alkaline solution?
Greater than 7
What is the pH of a neutral solution?
7
Name an indicator other than litmus or universal indicator
Methyl orange or phenolphthalein
What is the general word equation for neutralisation?
acid + base –> salt + water
What happens to the pH if a base or alkali is added to an acid?
It increases
What type of salts are formed from hydrochloric acid?
Chlorides
What type of salts are formed from nitric acid?
Nitrates
What type of salts are formed from sulfuric acid?
Sulfates
What type of salts are formed from phosphoric acid?
Phosphates
Which acid could have formed this salt?
Na3PO4
Phosphoric acid
Which acid could have formed this salt?
MgSO4
Sulfuric acid
Which compound would react with hydrochloric acid to produce CuCl2?
More than one answer is possible
Copper oxide
OR
Copper hydroxide
OR
Copper carbonate
What is the ionic equation for neutralisation?
H+(aq) + OH-(aq) –> H2O(l)
What is the general word equation for the reaction between an acid and a carbonate?
acid + carbonate –> salt + water + carbon dioxide
What is the general word equation for the reaction between an acid and a metal?
acid + metal –> salt + hydrogen
What is a dilute acid?
A solution of acid with a low ratio of acid to volume of solution (i.e. a low concentration of acid)
What is a concentrated acid?
A solution of acid with a high ratio of acid to volume of solution (i.e. a high concentration of acid)
What is a strong acid?
An acid that is fully ionised in solution
What is a weak acid
An acid that is partially ionised in solution
What is the name of the type of graph shown?
pH titration curve
for a strong acid added to a strong alkali
At what point on the graph is the concentration of hydroxide ions greatest?
0 cm3 (pH 13)
At what point on the graph is the concentration of H+ ions greatest?
50 cm3 (pH 1.4)
At what volume of acid added is the concetration of hydrogen and and hydroxide exactly equal?
25 cm3
What is electrolysis?
A process in which an electric current is passed through a compound, causing a chemical change.
What is the name for the solution or liquid in electrolysis which contains mobile ions and conducts electricity?
Electrolyte
What is the name for the two inert substances (often graphite) used in electrolysis.
Electrodes
What is the name of the positive electrode in electrolysis?
The anode
What is the name of the negative electrode in electrolysis?
The cathode
What happens to positive ions during electrolysis?
They gain electrons at the cathode
What happens to negative ions during electrolysis?
They lose electrons at the anode
What are positive ions known as?
Cations
What are negative ions known as?
Anions
What is meant by the term “discharged” in the context of electrolysis?
When ions gain or lose electrons to become atoms or molecules at an electrode
What would be the product formed at the anode in the electrolysis shown?
Bromine (Br2)
What would be the product formed at the cathode in the electrolysis shown?
Lead (Pb)
At which electrode is oxidation occuring?
Anode
At which electrode is reduction occuring?
Cathode
Why do salts need to be molten or dissolved in solution to be electrolysed?
Because the ions in a solid salt cannot move, so cannot conduct electricity.
What two ions are always present in the electrolysis of an aqueous solution?
H+ and OH-
During the electrolysis of water, what is produced at the cathode?
Hydrogen
During the electrolysis of water, what is produced at the anode?
Oxygen
When water is electrolysed, what is the half equation for the reaction that occurs at the cathode?
4H+ + 4e- –> 2H2
OR 2H+ + 2e- –> H2
When water is electrolysed, what is the half equation for the reaction that occurs at the anode?
4OH- –> O2 + 2H2O + 4e-
In the electrolysis of solutions, what rule can be used to predict what is produced at the cathode?
If ions from a metal that is more reactive than hydrogen are present, hydrogen ions are discharged to form hydrogen. If ions from a metal that is less reactive than hydrogen are present, the metal ions are discharged to form the metal.
In the electrolysis of solutions, what rule can be used to predict what is produced at the anode?
Oxygen is produced at the anode, unless halide (group 7) ions are present (in high enough concentration), in which case the halogen (group 7 element) is produced.
in GCSE chemistry, you can assume a suffiecient concentration of halide
Which of these metals are more reactive than hydrogen?
sodium; copper; gold
sodium
Which of these metals is less reactive than hydrogen?
platinum; lead; aluminium
platinum
What would be formed at the cathode during the electrolysis of aqueous potassium chloride?
hydrogen
What would be formed at the anode during the electrolysis of aqueous potassium chloride?
chlorine
What would be formed at the cathode during the electrolysis of aqueous copper sulfate?
copper
What would be formed at the anode during the electrolysis of aqueous copper sulfate?
oxygen
What would be formed at the cathode during the electrolysis of aqueous sodium hydroxide?
hydrogen
What would be formed at the anode during the electrolysis of aqueous sodium hydroxide?
oxygen
If you want to coat a piece of copper with silver by electroplating, what should the anode be made of?
silver
If you want to coat a piece of copper with silver by electroplating, what should the cathode be made of?
the piece of copper
If you want to coat a piece of copper with silver by electroplating, what would be a suitable electrolyte?
silver nitrate solution
nitrate salts are commonly used as they have good solubility
In the purification of copper by electrolysis which electrode consists of the impure copper?
the anode
In the purification of copper by electrolysis which electrode consists of the pure copper?
the cathode
In the purification of copper by electrolysis what happens to the impurities?
They fall from the anode and collect at the bottom of the electrolyte