C5 Flashcards
Why is electrolysis used to extract some metals?
If the metal reacts with carbon or is too reactive to be extracted using carbon
What type of reaction happens when a compound breaks down?
Decomposition
What type of indicator is used in a titration?
A single indicator because it has a sudden colour change (end-point)
What is the reaction between an acid and alkali called?
Neutralisation reaction: Acid + Base –> Salt + Water
What is an alkali?
An alkali is a base that dissolves in water to form a solution with a pH greater than 7. Alkalis form OH- ions in water.
What is an acid?
An acid is a substance that forms aqueous solutions with a pH of less than 7. Acids form H+ ions in water.
What is a weak acid?
A weak acid is partially ionised in aqueous solution
What is a titration used for?
If the volumes of 2 solutions that react completely are known and the concentration of 1 solution is known, the concentration of the other solution can be calculated.
What is a strong acid?
A strong acid is an acid that is completely ionised in aqueous solution
What is a reaction that separates a metal from its oxide called?
A reaction that separates a metal from its oxide is called a reduction reaction
What is a pipette used for?
To measure a fixed volume accurately
What is a pH scale?
A pH scale is a measure of how acidic or alkaline a solution is
What is a displacement reaction?
When a more reactive metal can displace a less reactive metal from a compound
What is a burette used for?
To measure a variable/continuous volume
What is a base?
A base is a substance greater than a pH of 7
What happens when an acid reacts with a metal?
Acid + Metal —> Salt + Hydrogen
What happens when an acid reacts with a metal oxide/hydroxide?
Acid + Metal Oxide/Hydroxide —> Salt + Water
What do we call reactions which involve both oxidation and reduction reactions?
Redox reactions
What do metals form?
Positive ions, they lose electrons. All elements in the reactivity series form positive ions.
What are the products of the reaction of sodium and water?
Sodium Hydroxide + Hydrogen
Steps of a titration
- alkali in burette
- acid in a conical flask measured out with 25cm^3
- add a few drops of indicator
- add alkali to acid until colour changes
- swirl conical flask
- add alkali drop wise towards the end
- note final burette reading
- repeat for accurate results
Name an indicator suitable for a titration
Methyl orange (yellow in alkalis and red in acids)
Name a strong acid
Hydrochloric acid, nitric acid, sulfuric acid
Metal carbonates and metal hydroxides are examples of
Bases
How can you form a metal hydroxide and hydrogen gas?
Metal + Water —> Metal Hydroxide + Hydrogen
Describe a method to make pure, dry crystals of magnesium sulfate from a metal oxide and dilute acid
- Pour sulfuric acid and excess magnesium oxide into a conical flask
- Heat it on a bunsen burner and stir with a glass rod
- After 3-4 minutes, filter out the excess magneisum oxide using a filter paper and a flask
- Boil the filtrate using an evaporating basin
- Move the bunsen burner in and out to make sure crystals form
- Leave to allow all water to evaporate in evaporating basin
____ + __ __ —> Salt + Water + Carbon Dioxide
Acid + Metal Carbonate
