EL 9: How salty? Flashcards
What is an acid?
A compound that disassociates in water to produce hydrogen ions
What is a base?
A compound that reacts with an acid - is a proton acceptor - to produce water and a salt
What is neutralisation?
When an acid and alkali react and a salt is formed
What is an alkali?
A base that dissolves in water to produce hydroxide ions (OH-)
What is a salt?
Is a product of neutralisation (when a H+ of an acid is replaced by a metal ion)
What is a strong acid?
Fully dissociates in an aqueous solution
What is a weak acid?
Partially dissociates in an aqueous solution
What is a key property of the group 2 oxides and hydroxides?
They are bases, they react with acids to produce salts
Acid + Base = Salt + Water
What is the general definition of an acid?
A substance that donates H+ in a chemical reaction
What is the general definition of a base?
A substance that accepts the H+ in a chemical reaction
What do you need before you can start a titration?
A standard solution
What is a standard solution?
Any solution that you know the concentration of
What does an acid + metal carbonate =?
Salt + H2O + CO2
What does an acid + Metal =?
Salt + H2
What does an acid + Metal oxide =?
Salt + H2O
What does an acid + Metal hydroxide =?
Salt + H2O
When making a standard solution must the bottom of the meniscus reach the line?
To make sure its accurate, you need to carry out every technique to the same level of precision
When making a standard solution must you invert the volumetric flask with the solution when its done?
To make sure its all mixed and to check the level of the meniscus again
Why must you make sure the standard solution is a suitable concentration compared to the solution you’re titrating it against?
If its too dilute, you’ll have to add loads before you reach an end point. If its too concentrated then tiny amounts will cause large changes in pH and your results may be inaccurate. So you should therefore make you standard solution to a similar concentration to the solution you’re titrating it against
What do titrations allow you to do?
Find put exactly how much acid is needed to neutralise a quantity of alkali
Why is it a good idea to do a rough titration?
To get a rough idea where the end point of the titration is, (the point where the alkali is exactly neutralised and the indicator changes colour).
Why do you need to do more than one accurate titration?
To calculate a mean titre and to see if your results are accurate
Why do you need to use a mean titration value (0.1 leeway)
To get an accurate mean titre
How do you work out the titre?
The final reading on the burette minus the initial reading on the burette (2 decimal places)
