Acids & Bases
Which ions do acids produce in aqueous solutions?
Hydrogen ions, H⁺
What is the pH of a neutral solution at about 25°C?
pH 7
What are the products of an acid reacting with a base?
Salt and water
Which apparatus holds the known solution during a titration?
A burette
How do you calculate the titre from burette readings?
Final reading − initial reading
What is a base that dissolves in water called?
An alkali
What does universal indicator help us estimate?
The pH of a solution
Complete the ionic equation: H⁺ + OH⁻ → ?
H₂O
Which apparatus accurately measures 25.0 cm³ of solution?
A volumetric pipette
Convert 20.10 cm³ into dm³.
0.02010 dm³
According to the proton definition, what does an acid do?
Donates a proton, H⁺
What colour does litmus turn in an alkaline solution?
Blue
What three products form when an acid reacts with a carbonate?
Salt, water and carbon dioxide
What must you use to fill a pipette safely?
A pipette filler
Calculate the moles in 20.10 cm³ of 0.100 mol/dm³ NaOH
0.002010 mol
Is ethanoic acid completely or partially dissociated in water?
Partially dissociated
A solution's pH decreases by one unit. By what factor does its H⁺ concentration increase under comparable conditions?
By a factor of 10
Which gas is produced when magnesium reacts with hydrochloric acid?
Hydrogen
What should you do when approaching the titration end-point?
Add the solution drop by drop and swirl the flask.
In a 1:1 reaction, 0.002010 mol of HCl is present in 25.0 cm³. Calculate its concentration.
0.0804 mol/dm³
What is the difference between acid strength and concentration?
Strength describes the extent of dissociation; concentration describes the amount per dm³.
Why is an indicator added during a titration?
Its sudden colour change helps identify the end-point.
In HCl + NaOH → NaCl + H₂O, why are Na⁺ and Cl⁻ called spectator ions?
They remain unchanged during the reaction.
Which liquids should be used to rinse the burette, pipette and conical flask, respectively?
NaOH solution, HCl solution and distilled water.
During titration, too much alkali is added past the end-point. How does this affect the calculated HCl concentration?
It makes the titre too large, so the calculated HCl concentration is too high.