Titration Flashcards
How To carry out a titration
- Using a pippet measure 25cm³ of a solution of known concentration and add it to a conical flask with an indicator
- Add other solution into a burette till zero
- slowly open the tap while swirling the flask until the colour change slows down
- add drop by drop until endpoint is reached
- repeat until concordant results (0.1cm3)
How to prepare a standard solution
- Weigh the solid accurately
- dissolve in less distilled water than is needed to fill the flask in a beaker
- pour into a flask rinsing the beaker with more distilled water making sure to fill till exactly the graduation line for accuracy
(view at meniscus at eye-level) - invert flask several times for consistency
What is the uncertainty of the burette?
0.05cm³
How much is the volumetric flask filled?
The bottom of the meniscus of the liquid should be touching the graduation
What can titration be used for?
- Finding the concentration of a solution
- Identification of unknown chemicals
- Finding the purity of a substance
What is the term standard solution?
A solution of known concentration
How do you calculate the mean titre
Add two concordant results and divide by two
What should you do to obtain reliable results for a titration?
Repeat until concordant results of acquired and calculate mean
why is it important to rapidly put the bung into the conical flask after adding sulfuric acid
The reaction starts as soon as the acid is added so CO2 will start to produce so use bung the to reduce the amount of CO2 that escapes
What are the possible errors made in this investigation of volume of gas produced
the reaction may be incomplete
some gas could have escaped before the bung is placed
some gas may be dissolved in water meaning a smaller volume would be collected than was released
Assuming that your sample of CuCO3.Cu(OH)2 contains exactly equal amounts, in mol, of CuCO3
and Cu(OH)2, what percentage by mass of CuCO3 in CuCO3.Cu(OH)2 would you expect?
123.5/ 221 x 100 = 55.9
Determine the size of the divisions on the measuring cylinder that you used to collect the carbon
dioxide. Calculate the percentage uncertainty in the value of the gas volume.
1cm / 125 x100 = 0.8
Calculate the percentage error in the value of the mass.
0.66%
Explain why it’s not necessary to calculate the percentage uncertainty of volume of H2SO4 used
The acid is in excess, so the actual amount is not required for the calculation
How would these errors affect the final result And how could they be fixed
The loss of gas means that less CO2 is collected. This gives a smaller % by mass CuCO3 than the actual value place the bung in quicker
When copper rooftops turn green, the copper reacts with oxygen, water vapour and carbon dioxide in the air to form CuCO3·Cu(OH)2(s). Construct an equation for this reaction
2Cu(s) + H2O(g) + CO2(g) + O2(g) -> CuCO3.Cu(OH)2 (s)
