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Terms in this set (78)
What do you use to test the PH of a solution?
Use an indicator
What PH scale goes from ...
What does the PH scale measure?
How acidic or alkaline a solution is
Describe the PH scale?
The lower the PH of a soluton, the more acidic it is. The higher the PH of a solution, The more alkaline it is. A neutral substance has a PH of 7
Whats an indicator?
Is a dye that changes colour depending on whether its above or below a certain PH.
What is a wide range indicator?
They are substances that grually change colour as the PH changes
What are indicators useful for?
estimating the PH of a solution
What can a PH probe be used for?
A PH prbe gets attatched to a PH meter can be used to measure Ph electronically, so it can be more accurate than an indicator
What happens when acids dissolve in water?
They form solutions with a PH less than 7
What do acids form in water?
What do bases have a PH of?
They have a PH greater than 7
What are alkalis?
They are bases that dissolve in water to form solutions with a PH greater than 7
What do alkalis form in water?
OH^- ions. e.g solid metal hydroxides are alkalis
The reaction between acids and bases is called what?
Neutralisation - acid + base -> salt + water
How can neutralisation between acids and alkalis be shown?
They can be shown using H+ and OH^- - H+ + OH^- -> H20
Hydrogen ions react with what to produce water?
They react with hydroxide
Metal oxidesand metal hydroxides react with what to form salt and water?
They react with acids, The salt that forms depends upon the acid and the mtal ion in the oxide or hydroxide
HCL reacts to form what?
H2SO4 reacts to form what?
HNO3 reacts to form what?
Metal carbonates are what?
They are bases, They react with acids to produce a salt, waterand carbon dioxide
What does the reactivity series do?
It lists metals in order of reactivity -> how reactive they are
The reactivity series-
Metals react to form what?
positive ions, so for metals their reactivity depends on how easily they lose electrons and form positive ions
The higher up the reactivity series a metal is, the more easily it what?
forms positive ions
What are carbon and hydrogen?
They are non-metals but are often still included in the reactivity series
Lots of common metals like iron andd aluminium react with what to form oxides?
They react with oxygen, This process is an example of oxidation.
What is an ore?
An ore is a type of rock that contains metal compounds, most metals are found in the earth as ores
These oxides are often the what that the metals are extracted from?
Gain of oxygen
Loss of oxygen
Some metals can be extracted from their ores using what?
Using a reaction with carbon
The reactivity series can tell you what?
If a metal can be extracted with carbon
Metals above carbon are extracted using what?
Why is electrolysis expensive?
Because it takes lots of energy to melt the ore and produce the electricity
How is electrolysis also used ?
To extract metals that react with carbon
Metals below carbon in the reactivity series can be extracted by what? and why?
reduction using carbon . Because carbon can only take the oxygen away from metals which are less reactive than carbon itself is
Metals that are so unreactive are found in the earth as what?
The metal itself e.g gold
Metals reat to form what?
Some metals react with acods to produce what?
A salt and hydrogen gas
What reacts explosively with acids?
very reactive metals like potassium. sodium , lithium and calcium
what reacts less violently with acids?
Less reactive metals such as magnesiun, zinc iron
In general, copper wont react with what?
with cold, dilute acids
Many metals also react with what?
water metal + water -> Metak hydroxide + oxygen
Which metals react with water?
potassium, sodium, lithium and calcium
Which metals wont react with water?
zinc, iron and copper
Experiment: What to do to compare the reactivity of metals?
Watch how quickly bubbles of hydrogen are formed in their reactions with water or acid, The more reactive the metals the faster the bubbles will form
Experiment: How to measure the temperature change of the reactions in a set period of time?
The more reactive the metal , the greater the temperature change should be
Experiment: for these experiments to be fair the what should be the same each time?
The mass and surface area
What do displacement rections involve?
one metal displacing (kicking out) another one out of a compound
Whats is the displacement reaction rule?
A MORE REACTIVE METAL WILL DISPLACE A LESS REACTIVE METAL FROM ITS COMPOUND
What does electrolysis use to cause a reaction
It uses electricity
Electrolysis means doing what with electricity?
What is an electrolyte?
Its a liquid solution that can conduct electricity
What is an electrode?
Its a solid that is put in the electrolyte and conducts electricity
What happens in electrolysis?
An electric current is passed through an electrolyte, The ions move towards the cathode (negative electrode). here they gain electrons. Negarive ions in the electrolyte moves towards the anode (positive electrode), Here they lose electrons. The ions form the uncharged element. The ions be discharged from the electrolyte. A flow of charge is created through the electrolyte as the ions travel to the electrodes.
Why can molten ion compounds be electrolysed?
Because the ions can move freely and conduct electricity.
Molten ionic liquids are always broken up into their what?
In electrolysis where is the metal formed?
At the cathode
In electrolysis where is the non-metal formed?
At the anode
The electrodes should be what so they dont react with the electrolyte?
They should be inert (unreactive)
When molten lead bromide is electrolysed what happens?
Lead forms at the cathode and bromide forms at the anode
Metals can be extracted from their ores using what?
Aluminium is extracted from an ore that contains what?
Aluminium oxie has a very high melting point so what happens?
Its mixed with a substance called cryolite
What does cryolite do?
It lowers the melting point
In electrolyte what is the anode make of?
graphite (carbon). It can react with oxygen and produce carbon dioxide so it needs to be replaced regularly.
What does the symbol show?
In the reaction the symbol shows that its reversible.
Water can break down into what?
H+ and OH^- ions
In salt solutions that contain water, there will be ions from where?
From the ionic compounds, hydrogen ions (H+), Hydroxide ions (OH^-) from water
In electrolysis H+ ions wil move where
To the cathode
In electrolysis what does it mean if hydrogen gas forms?
The metal was more reactive than hydrogen
In electrolysis what does it mean if a solid layer of the pure metal forms?
The metal was les reactive than hydrogen
In electrolysis: If the salt contains halide ions (Cl^-, Br^-, I^-) what will happen?
Chlorine, bromine or iodine will form at the anode
In electrolysis: If bo halide ions are present then what happens?
Then OH^- ions lose electron and oxygen will form at the anode
In an electrolysis experiment what happens to chlorine?
Chlorine bleaches damp litmus paper, turning it white
In an electrolysis experiment what happens to Hydrogen?
Hydrogen makes a squeaky pop with a lighted splint
In an electrolysis experiment what happens to oxygen?
Oxygen will relight a glowing splint
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