Module 2 Chapter 4 (part 1) Flashcards
What do all acids contain in there formula
They all contain hydrogen in their formulae
What happens when acids are dissolved in water
They release H+ ions into the water
What is the Bronstead Lowry definition of an acid
They are proton donors
What is the formula of ethanoic acid
CH3COOH
What is a strong acid
A strong acid completely disassociates when dissolved in water. All molecules release H+ ions
What is a weak acid
A weak acid partially dissociates when dissolved in water. Only a small proportion of the molecules release H+ ions.
What happens to the H+ ions released
The H+ ion will then join with a water molecule making a hydroxenium ion.
What is the equation for a hydroxenium ion forming
H+ (aq) + H2O (l) <-> H3O +
What happens when the acid is stronger
The more free H+ ions are released into solution. The greater the number of free H+ ions.
What does a greater number of H+ ions in the solution mean
It means that the PH value of the acid will be lower.
What are most organic acids
They are weak acids
What is the definition of a base
A base neutralises an acid to form a salt
What is the definition of an alkali
An alkali is a soluble base that releases OH- ions into solution.
what happens in a neutralisation reaction
H+ ions react with a base to form a slat and water.
What is the ionic equation for all neutralisation reactions
H+ + OH- -> H2O
What is the word equation for an acid and base
Acid + base -> salt + water
What is the work equation for an acid and base
Acid + base -> salt + water
What is the word equation for an acid and alkali reacting
Acid + alkali -> salt + water
What is the word equation for an acid and metal reacting
Acid + metal -> salt + hydrogen
What is the word equation for an acid reacting with a carbonate
Acid + carbonate -> salt + water + carbon dioxide
what do you call a salt made form hydrochloric acid
- Chloride
what do you call a salt made form sulphuric acid
Sulfate
what do you call a salt made form nitric acid
- Nitrate
what do you call a salt made form ethanoic acid
Ethanoate
What is the ethanoate ion
CH3COO -
What happens when an acid is neutralised by metal oxides and hydroxides
Only a salt and water is formed
What is a titration used for
Finding the concentration for a solution
Identification of unknown chemicals
Finding the purity of substances - important for quality control in pharmaceutics
What is a standard solution
A solution of a known concentration
What is the titre volume
The minimum volume of solution needed to reach the end point in a titration
How do you make a standard solution (1-3)
1) The solid is weighed accurately
2) The solid is dissolved in a. Beaker using less distilled water than will be needed to fill the volumetric flask to the mark
3) Solution transferred to a volumetric flask. The last traces of solution are rinsed into the flask with distilled water
What is steps 4-5 of making a standard solution
4) Flask is carefully filled to the graduation line by adding distilled water a drop at a time until the bottom of meniscuses lines exactly up with the mark at eye level
5) Slowly invert the volumetric flask several times to mix the solution this step is important for consistency.
What are two possible errors that can occur when making a standard solution
- The flask is filled with water over the graduation line
- The flask is not inverted
What are the first 4 steps when conducting a titration
- Use a volumetric pipette to measure the volume of standard solution into a conical flask
- Add the other solution into brunettes, record the initial burette reading to nearest +- 0.5cm cubed
- Add indicator to solution in conical flask
- Run the solution in burette into the solution in conical flask, swirling the flask as you do so mix the solutions together.
What are the steps when doing a titration (5-8)
5) The end point is when the indicator changes colour. this indicates when the volume of one solution that exactly reacts with the volume of the second solution.
6) Record final burette reading. the difference is the titre volume
7) A quick run is done to get an approximation
8) Titration is repeated at least 3 or 2 times until two or more concordant readings are measured.
What values do you choose for the mean titre
The concordant values
What are concordant titre values
Within 0.10cm cubed of each other