C2-5 Salts and electrolysis Flashcards
(21 cards)
What do acids produce when added to water?
Hydrogen ions
What is an aquous solution?
When a substance is disolved in water.
What ph does an acidic aolution have?
Less than 7
What does a base do to an acid?
Neutralises it
What are alkalis?
Bases that disolve in water to make alkaline solutions. They produce hydrogen ions and have ph values of more than 7
What do acids and metals produce when reacting?
A salt and a hydrogen gas.
Is pure water positive? What is its ph?
Neutral, 7
What are the products of neutralisation?
A salt and water.
How can we make a soluble salt? How can we know the reaction is complete?
Acid and an alkali. No visible change is seen and therefore we must use an indicator.
What is precipitation?
The process in which some pollutants are removed from water by adding substances that react with the pollutant metal ions.
What is the process that uses electricity to break down iobic compunds called?
Electrolysis.
In electrolysis, what is the substance thT is broken down called?
Electrolyte.
Why are compounds only able to be electrolysed if molten or in solution?
Because otherwise their electrons aren t able to move.
WhaT happens to the electrolyte s ions?
They move towards the electrodes where they are discharged to make elements.
What do negative ions form in electrolysis?
They go to the positive elctrode and form non metallic elements.
What is reduction?
It is when positively charged ions go to the negative electrode and gain electrons to be neutralised.
What is oxidation?
When negatively charged ions go to the postive elctrode and loose electrons to be become neutral.
How is aluminium ectracted from its ore? Why?
Electrolysis as its more reactive than carbon.
Why isaluminium oxide mixed with molten cryolite?
To lower its melting point.
What do we get from electrolysing brine? What are they key for?
Chlorine gas- used to kill bacteria in drinking water, making desinfectants and plastics.
Hydrogen gas- used to make margarine and hydrochloric acid
Sodium hydroxide- making soap, paper, bleach etc
Why may an object be electroplated?
To improve its appearance, protect the surface, and use smaller amounts of precious metals.
