Quantitative Chemistry Flashcards
Improvements to a method of titration that would increase the accuracy of the result
Swirl the solution
White tile infer the flask
Add acid dropwise (near the endpoint)
Repeat and calculate mean
One reason for anomalous point when investigating the temperature change during the reaction between citric acid and sodium hydrogencarbonate solution
Didn’t stir the solution enough
Explain the shape of the graph (Temp of solution decreases until the 1.5g of citric acid is added) in terms of energy transfers taking place
Temperature decreases initially as energy is taken in by the reaction from the solution (endothermic)
When 1.5g is added the citric acid is in excess
So the temperature increases as energy is transferred from the room to the solution
Give two reasons why a burette is used for the citric acid solution
Can add the citric acid in small increments (drop by drop)
More accurate than a measuring cylinder
Explain why an acid can be described as both strong and dilute
Strong because it completely ionised in aqueous solution
Dilute because small amount of acid per unit volume
Explain why the student should use a pipettes to measure the dilute sulphuric acid and a burette to measure the sodium hydroxide solution
Pipette measures a fixed volume accurately
But burette measures variable volume (drop by drop)
What is meant by a weak acid
Produces hydrogen ions in aqueous solution
But is only partially ionised
What would happen at then end point of a titration with citric acid and sodium hydroxide solution
Indicator changes colour
From blue to yellow
When the acid and alkali are neutralised
Explain why a Pipette is used to measure the sodium hydroxide solution but a burette is used to measure the citric acid solution
As Pipette measures one fixed volume
But burette measures variable volumes
