Chapter 4 Flashcards
Formula of hydrochloric acid
HCl
Formula of sulphuric acid
H2SO4
Formula of nitric acid
HNO3
Formula of ethanoic acid
CH3COOH
Formula of sodium hydroxide
NaOH
Formula of potassium hydroxide
KOH
Formula of ammonia
NH3
What is an acid?
An acid is a substance that will release H+ ions when in an aqueous solution
What is an alkali?
An alkali is a soluble base and will release OH- ions in an aqueous solution
What is a base?
Bases are compounds that neutralise acids but do not dissolve, by accepting a hydrogen ion to form a salt
What is the definition of a strong acid?
A strong acid is an acid that releases all its hydrogen atoms as H+ ions and completely dissociates in aqueous solutions
What is the definition of a weak acid?
A weak acid is an acid that only releases a small proportion of its available hydrogen atoms into the solution as H+ ions. A weak acid partially dissociates in an aqueous solution.
Examples of a strong acid:
HCl
H2SO4
H3PO4
Examples of a weak acid
CH3COOH
What is the ionic equation for neutralisation by an alkali including state symbols?
H+(aq) + OH-(aq) –> H2O(l)
What is produced when an acid is neutralised with a metal oxide/hydroxide?
An acid is neutralised by a metal oxide/hydroxide to form a salt and water only.
CuO(s) + H2SO4 (aq) –> CuSO4 (aq) + H2O(l)
What is produced when an acid is neutralised by an alkali?
An acid is neutralised by an alkali to form a salt and water only.
Full equation: HCl(aq) + NaOH(aq) –> NaCl(aq) + H2 (l)
Ionic equation: H+(aq) + OH-(aq) –> H2O(l)
What is produced when an acid is neutralised with a carbonate?
An acid is neutralised by a carbonate to form a salt, water and carbon dioxide.
ZnCO3(s) + H2SO4(aq) –> ZnSO4(aq) + H2O(l) + CO2(g)
What is a titration?
A titration is a technique used to accurately measure the volume of one solution that reacts exactly with another solution to find an unknown concentration.
What can a titration be used for?
Finding the concentration of a solution
Identification of unknown chemicals
Finding the purity of a substance
What is a standard solution?
A solution of known concentration
What is used to make up a standard solution very accurately?
A volumetric flask
Method to preparing a standard solution:
- The solid is first weighed accurately
- The solid is then dissolved in a beaker using less distilled water than will be needed to fill the volumetric flask to the mark.
- This solution is then transferred to a volumetric flask. The last traces of the solution are rinsed into the flask with distilled water.
- The flask is filled to the graduation line by adding distilled water a drop at a time until the bottom of the meniscus lines up.
- Finally the volumetric flask is slowly inverted several times to mix the solution thoroughly.
What things are done to ensure an accurate solution when preparing a standard solution?
The graduation mark and meniscus must be viewed at eye level
Volumetric flask must be used
Consistent results are found from inverting the volumetric flask several times