Q9s Flashcards
Define according to Bronsted-Lowry theory an acid?
An acid is a proton donor or H+ donor.
Define according to Bronsted-Lowry theory a base?
A base is a proton acceptor or H+ acceptor.
Define according to Bronsted-Lowry theory an acid-base conjugate pair?
Two species that differ by a proton or H+.
Distinguish between a weak acid and a strong acid?
A weak acid is a poor proton donor or H+ donor and is slightly dissociated. A strong acid is a good proton donor or H+ donor and is fully dissociated.
Give an example of a weak acid?
Acetic acid (vinegar), ethanoic acid, phosphoric acid, citric acid, and methyl orange.
Define a concentrated acid solution?
A concentrated acid solution has a large quantity of acid (solute) in a small volume of water (solvent).
Define a dilute acid solution?
A dilute acid solution has a small quantity of acid (solute) in a relatively large volume of water (solvent).
Define a concentrated base solution?
A concentrated base solution has a large quantity of base (solute) in a small volume of water (solvent).
Define a dilute base solution?
A dilute base solution has a small quantity of base (solute) in a relatively large volume of water (solvent).
Define Amphoteric?
Amphoteric is a substance that can act as an acid or a base.
Define pH?
pH = -log10[H+] or pH = -log10[H30+]. It is the hydrogen ion concentration.
Define a standard solution?
A standard solution is a solution of known concentration.
Define a saturated solution?
A saturated solution is a solution with the maximum quantity or mass of solute dissolved at that temperature.
Define Anhydrous?
Anhydrous contains no water or is dried.
Define a primary standard?
A primary standard is stable, can be weighed accurately, pure, solid, and does not lose or absorb water.
How should the pipette be prepared before use?
Rinse with deionised water and then with the solution it will deliver. Use a pipette filler, fill to the zero mark, release liquid, and allow time to drain.
Why was a pipette filler used to fill the pipette?
For safety and to avoid swallowing.
How should the burette be prepared before use?
Rinse with deionised water and then with the solution it will deliver. Fill using a funnel and remove it. Open the tap to reach the zero mark and adjust to volume at eye level.
How should the conical flask be prepared before use?
Rinse with deionised water only.
Why is a conical flask suitable for use as a titration flask?
Its sides can be washed down easily, allows swirling, and prevents splashing.
Why are the sides of the conical flask washed down with deionised water?
To ensure all the solution reacts.
What is the procedure for transferring exactly 25.0 mL of solution from the pipette to a conical flask?
Allow the pipette to drain for a few seconds and touch the tip against the wall of the titration flask.
Why was a conical flask placed on a white tile?
To allow the color change/end point to be seen clearly.
How do you read the burette?
Read at eye level, at the bottom of the meniscus, and use white paper to read clearly.
How could the presence of an air bubble in the nozzle of a burette affect the result obtained in a titration reading?
It could cause an inaccurate reading.
Define a volumetric flask?
A volumetric flask is used to make up a standard solution. It has a narrow neck for accurate measurement and can be stoppered for mixing.
Procedure to make up a standard solution?
Weigh out sodium carbonate, add to a beaker with deionised water, dissolve, transfer to volumetric flask, fill to mark with deionised water, stopper and invert several times.
Why is it important not to use tap water in the experiment?
Tap water contains ions or impurities, which could interfere with the result.
Define an acid-base indicator?
An acid-base indicator is a substance that changes color in solutions of different pH.
Indicator used for strong acid vs strong base titration?
Methyl orange (red to yellow) or phenolphthalein (colourless to pink).
Indicator used for strong acid vs weak base titration?
Methyl orange (yellow to red).
Indicator used for weak acid vs strong base titration?
Phenolphthalein (colourless to pink).
Indicator used for strong base vs weak acid titration?
Phenolphthalein (pink to colourless).
Why should only one or two drops of indicator be used?
Indicators are weak acids/bases, and too much could affect the accuracy of the result.
Define a saturated solution?
A saturated solution has the maximum quantity or mass of solute dissolved at that temperature.
Define anhydrous sodium carbonate?
Anhydrous sodium carbonate contains no water and is dried.
Define a primary standard?
A primary standard is stable, pure, solid, and can be weighed accurately without absorbing or losing water.
Common use of limewater in the laboratory?
To detect the presence of carbon dioxide gas.
