The dilution
The 30 gram sample is placed in the volumetric flask and distilled water added and made up to the mark
Click to hide this information
The dilution
The 30 gram sample is placed in the volumetric flask and distilled water added and made up to the mark
Click to hide this information
The titration
20.10mls of 0.1M HCl solution is added to the 20ml sample before the indicator changed colour.
Click to hide this information
Taking a sample.
Pipettes are used to deliver accurate volumes of sample solutions.
Click to hide this information
Solution
Step 1 Calculate
the mole of HCl added by
the burette
Mole = volume X concentration
= 0.0201 X 0.1 = 0.002
Step 2 Using the equation calculate the number of mole of calcium carbonate present required to react completely
0.002/2 = 0.001mole of calcium carbonate in the 20ml sample.
Step 3 Find the mole of calcium carbonate in the 30g sample
(250/20) X 0.001
=0.0125
Step 4 Find the mass of calcium carbonate presetn in the 30g sample
mass = mole X formula mass = 0.0125 X100 = 1.25grams
Step 5 Calculate the percentage of mass due to calium carbonate
(1.25/30) X 100 = 4.2%
Click to hide the solution
|
Volumetric analysis exercise 11 |
|||||||||
|
Irene placed 30 grams of impure calcium carbonate into a 250ml volumetric flask and added distilled water to the mark. 20mls of the resulting solution were pipetted into a conical flask and titrated against a 0.1M HCl solution. The results of the titration are shown on the right. What is the percentage of calcium carbonate in the sample.
Atomic mass Ca =40, O =16, H=1 |
|
||||||||
|
The equation for the reaction is shown below.
|
|||||||||
|
Solution |
|||||||||