C2.5 Flashcards
Name an alkali:
Sodium hydroxide.
What is a base?
Substances that can neutralise acids.
What ions do all acids form when we add them to water?
Hydrochloric acid.
What does the state symbol (aq) stand for?
Shows that the ions are in an aqueous solution (Dissolved in water).
What ions do all alkalis form when we add them to water?
Hydroxide ions.
What does the state symbol (s) stand for?
Solution.
What do we use to show how acidic or alkaline a solution is?
pH scale.
What does e reaction between an acid and a metal produce?
Salts.
What does the state symbol (g) stand for?
Gas.
What is formed when an acid plus a base react?
Salt and water are formed.
Name the salt formed when dilute sulphuric acid reacts with zinc oxide:
Sulfates.
What does the state symbol (l) stand for?
Liquid.
What salt is used as a fertiliser to provide crops with nitrogen?
Ammonium nitrate.
Name two other important ways of making salts from solutions:
- react an acid and alkali together to form a soluble salt
- reacting solutions of two soluble salts together
What is a precipitate?
Insoluble solid formed.
What is electrolysis?
Means splitting up using electricity.
What do we call the substance broken down by electrolysis?
The electrolyte.
What happens during electrolysis?
Positively charged ions move to the negative electrode and at the same time the negative ions move to the positive electrode.
Which electrode do positive ions move to?
Negative electrode.
Which electrode do negative ions move to?
Positive electrode.
How do negative charged ions become neutral atoms in electrolysis?
They lose electrons.
How do positively charged ions become neutral atoms in electrolysis?
They gain electrons.
What is oxidation?
Losing electrons.
What is reduction?
Gaining electrons.
Why is aluminium used to make overhead power cables?
They have a low density but are very strong.
Why must aluminium oxide be molten for electrolysis to take place?
Enables the ions to move to the electrodes.
Are the oxide ions reduced or oxidised in the electrolysis of molten aluminium oxide? Why?
Oxidised because it loses 2 electrons.
What are the 3 products made when we electrolyse brine?
- chlorine gas is produced at the positive electrode
- hydrogen gas is produced at the negative electrode
- sodium hydroxide solution is also formed
What is chlorine used for?
To make a solution of bleach.
What is hydrogen used for?
Make sit very useful in ex food industry.
eg margarine
What is sodium hydroxide used for?
Used to make soap and paper.
Also bleach.
Name four metals that we can use to electroplate another metal:
- steel
- gold
- silver
- chromium
Why do we electroplate objects?
- to protect the metal beneath from corroding
- to make the object look more attractive
- to increase the hardness of a surface and its resistance to scratching
- to save money
Where are the nickel atoms oxidised?
In a solution.
What is formed when nickel atoms are oxidised?
Form nickel ions.
