Chemical Changes Flashcards
From what pH’s is an acidic solution ?
0-6 pH
What pH is a neutral solution ?
7
What pH is a more alkaline solution?
8-14
How can you measure the pH of a solution ?
1) An indicator - use universal indicator to determine the pH. Add the dye to the solution and then compare to a pH chart
2) pH probe - attached to a pH meter and is measured electronically . A more accurate way of testing the pH
What type of ions do acids form in water ?
H+ ions
A base is a substance with a pH greater than ..
7
What type of ions does an alkaline in water make ?
OH- ions
A reaction between an acid and a base is called what …
A neutralisation reaction
What is the symbol equation for the neutralisation reaction ?
H+ (aq) + OH-(aq) = H20
Strong acids do what in water ?
Completely ionise
Weaker acids do not do what in water ?
Ionise completely
If the concentration of a H+ ion is higher …
means what for stronger and weaker acids
The rate of reactions will be faster so strong acids react faster than the weaker acid at the same concentration
What is the general formula to find the concentration of H+ ions from the pH?
Factor H+ ion concentration changes by = 10^(-X)
X = is the difference in the pH
An acids strength tells you what ?
The proportion of acid molecules ionise in water
The concentration of an acid tells you what ?
How much acid there is in a certain volume
X + Y = Salt + Water
What are X & Y ?
1) X = Acid
Y = Metal Oxide
2) X= Acid
Y= Metal Hydroxide
Acid + Metal Carbonate = X + Y + Z
What are X , Y and Z?
X Salt
Y Water
Z Carbon Dioxide
What does the reactivity series base how reactive the metals are ?
How easily they lose their electrons
The higher up the list they Are the more reactive
What is in the reactivity series ?
Potassium Sodium lithium Calcium Magnesium Carbon Zinc Iron Hydrogen Copper
When a metal reacts with an acid how can you tell the sped of the reaction ?
How quickly hydrogen bubbles are given off Temperature Change (mass & surface area have to be the same )
Metal + Water = X + Y
What are X&Y?
X. Metal hydroxide
Y. Hydrogen
Metals react with oxygen to form oxides . What do they metals need to be extracted from and what sort of a reaction is it ?
Ores
Oxidation
What are the two ways to separate metals from their oxides ?
Oxidation
Reduction
What does OIL RIG Stand for ?
OIL - oxidation is lose of electrons ( and gain of oxygen )
RIG - reduction is gain of electrons ( and lose of oxygen )
Metal with higher reactivity have to be extracted by what and what are these metals ?
Electrolysis
Potassium , sodium , lithium , calcium , magnesium
The less reactive metals are extract by what and what are these metals ?
Reduction using carbon & blast furnace ?
Zinc , iron , copper
What is a redox reaction ?
When oxidation and reduction happens at the same time
What is the rule for a displacement reaction ?
A more reactive metal will always displace a less reactive metal from its compound
In dis placement reaction what happens to the metal ion and what happens to a metal atom ?
The metal ion gains electrons and is reduced
The metal atom loses electrons and is oxidised
What happens during electrolysis ?
1) an electric current is passes through an electrolyte ( liquid or solution that can conduct electricity/ a molten or dissolved ionic compound ). The ions move towards the electrodes ( a solid that can conduct electricity and is submerged in the electrolyte) , where they will react and the compound will decompose.
2) Positive ions in the electrolyte will move towards the cathode (-ve) and gains electrons - reduction
3) Negative ions move towards the anode (+ve) and lose electrons -oxidation
4) This creates a flow of charge
5) The uncharged element will be discharge from the electrolyte
Why can’t an ionic solid be electrolysed ?
Because the ions are in fixed positions and can’t move ?
During electrolysis positive metal ions are …. And Negative
non - metal ions are …..
Positive metal ions are reduced at the cathode
Negative non - metal ions are oxidised at the anode
In aqueous solutions there will be what type of ions from the water ?
Hydrogen ions and Hydroxide ions
During electrolysis os an aqueous solution at the cathode , if H+ ions and and metal ions are present what will be produced if what happens ?
Hydrogen if the metal ions form an elemental element which is more reactive than hydrogen
However If the elemental metal is less reactive than hydrogen the a pure metal is produced instead
What do half equations show ?
Show the reactions at the electrodes
