Standard Solutions (Leaving Cert Chemistry): Flashcards
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Definition of standard solution
Definition of standard solution
Solution with precisely known concentration
Main use of standard solutions
Main use of standard solutions
Volumetric analysis and acid-base titrations
Definition of primary standard
Definition of primary standard
Stable, pure, soluble solid that can be weighed accurately for standard solutions
First criterion for primary standards
First criterion for primary standards
High purity
Why high molecular mass needed in primary standards?
Why high molecular mass needed in primary standards?
Minimises impact of weighing errors on precision
Why stability in air needed in primary standards?
Why stability in air needed in primary standards?
Shouldn't lose/gain water from air
Why sulphuric acid not a primary standard?
Why sulphuric acid not a primary standard?
It's hygroscopic (absorbs water vapour from air)
Why sodium hydroxide not a primary standard?
Why sodium hydroxide not a primary standard?
It's deliquescent (absorbs water to form solution)
Why hydrated sodium carbonate not primary standard?
Why hydrated sodium carbonate not primary standard?
It's efflorescent (loses water of crystallisation)
Three examples of primary standards
Three examples of primary standards
Anhydrous sodium carbonate, NaCl, potassium hydrogen phthalate
Define hygroscopic
Define hygroscopic
Absorbs water vapour from air
Define deliquescent
Define deliquescent
Absorbs water from air to form a solution