UNIT2: Titration and colorimetry
(Assignment 1A)
Titration
Introduction
Titration is a method for quantitative chemical analysis to determine the
concentration of a specific element.It is done by using a solution of a
known concentration to find out a concentration of an unknown solution.
For this investigation we are identifying the concentration of an unknown
sodium hydroxide solution by:
-Making a standard solution of sodium carbonate
-Standardisation of hydrochloric acid
-Titration of hydrochloric acid with unknown sodium hydroxide solution
-Titration of hydrochloric acid with unknown sodium hydroxide solution
(pH method )
,Making a standard solution of sodium carbonate
Calibration of a balance
Calibrating balances is where you test the balances to see which
balance is more accurate.Calibrating the balances is an important step
for measuring sodium carbonate so we know how accurate the balances
are and which balance is better which is the whole point in
calibrating.The more accurate the balances the better it is which further
suggests you will get better results.
For this experiment we used these expensive weights that have been
made to weigh the exact amount to see how accurate balances are.
When calibrating the balance you have to turn the balance on and make
sure you the weight displayed on the balance is at 0 , and put a weight
on the balance every time you measure the weight displayed on the
balance starting from 100 and working your way up and a thing you
must do when you're dealing with more than one weight make sure you
put all the weights at the same time.
The results that i got for calibrating the balances if shown in the following
table:
Weight tested Weight displayed on Difference between
balance the two
100 100.94 0.94
200 203.02 3.02
300 304.76 4.76
400 405.12 5.12
500 505.43 5.43
From this table and results I got i can infer that as there are more weight
being tested there is a bigger weight difference between the two result
so the weight tested and the eight displayed on the balance, this can
further suggest that there will be a bigger percentage different and if
there's more weight added to the balance it will give less accurate and
precise results.
,Cleaning an use of volumetric glassware
Cleaning and use of volumetric glassware is also an important step to
because cleaning equipment and glassware it important because it will
prevent contamination if you don't do this it will affect your results and
observations when your doing an experiment and you will see your
solution contaminated with the chemical/solvent that you have used
before this suggests why it important that that you clean the equipment
properly to prevent this furthermore this can link to accuracy of results if
your equipment is not clean then it will decrease the chances of your
results being accurate which may lead to one of the reasons why you
might anomalous results meaning results which are not close to the
other values when doing repeats as an example.
Using volumetric glassware is a piece of equipment which has markings
which makes measuring the volume of liquids easier. We use these
pieces of equipment because they will provide accurate results because
they have markings in them so you know where to stop when adding a
solution or substance that you want to measure in the volumetric
glassware.
Risk assessment of standard solution
Hazard Possible harm Precaution
Dilute sodium Skin irritation Wear Gloves
carbonate Eye irritant Wear goggles
Broken glassware Can cause cuts and Wear gloves
get into your eye Wear goggles
Spillages Chemicals can get in Tidy workplace
contact with skin
Standardising solution of sodium carbonate
To make a standard solution of sodium carbonate you will have to make
a stock of solution of 250cm3 which has concentration of 0.5 mol
dm-3.Next we will have to calibrate the weighing balance that you will be
using to know which weighing balance is better to use.then you have to
weight approximately the amount anhydrous sodium carbonate that you
, will need and it should be around 1g from the calculated mass for my
results i got 1.4g so this is the value I will using in the calculations.
We then need to transfer the sodium carbonate into a larger beaker
which needs to be done accurately and precisely and make sure all of it
in so we have the same exact and amount and the mass which that
transferred.We then have to add 150cm3 of distilled water into the
beaker and stir it thoroughly until the sodium carbonate is fully
dissolved.We then need to transfer this solution into a 250cm3 flask and
mark where the meniscus is and make sure its labelled and that the
solution is mixed well.We then have to calibrate the pipette to see how
accurate they are and if they work or not.We then need to transfer
25cm3 of sodium carbonate solution using a pipette from the stock
solution the used previously into another 250cm3 volumetric flask .In that
volumetric flask add distilled water and fill it to 250cm3 and making sure
the solution is fully mixed and labelled .We then need to calculate the
exact concentration of the diluted sodium carbonate.
Calculations:
n=mass/Mr
n=1.4/106=0.0132
Mr of Na2CO3= 106
C=n/v
250/1000=0.25
C=0.0132/0.25=0.05mol/dm-3
So the concentration is 0.05col/dm-3
Comparison between a glass stirring rod and a magnetic stirrer
A glass stirring rod and a magnetic stirrer are both equipment that are
used to mix things. A glass stirring rod is made out of glass and it's more
fragile so it can easily break. This can be seen as a risk because it might
cause cuts to the skin and link to why it is important to wear gloves to
minimise this hazard of getting a cut from occurring .
Also it can't mix a solution evenly. A magnetic stirrer is magnetic so it
can stir the solution evenly because its done automatically because it
has a magnetic which prevents human error.I think as magnetic stirrer is
better than a a glass rod because a magnetic stirrer can be left for a
longer period of time without someone tending to it and it's more reliable
because it can automatically be done unlike glass rod someone has to
(Assignment 1A)
Titration
Introduction
Titration is a method for quantitative chemical analysis to determine the
concentration of a specific element.It is done by using a solution of a
known concentration to find out a concentration of an unknown solution.
For this investigation we are identifying the concentration of an unknown
sodium hydroxide solution by:
-Making a standard solution of sodium carbonate
-Standardisation of hydrochloric acid
-Titration of hydrochloric acid with unknown sodium hydroxide solution
-Titration of hydrochloric acid with unknown sodium hydroxide solution
(pH method )
,Making a standard solution of sodium carbonate
Calibration of a balance
Calibrating balances is where you test the balances to see which
balance is more accurate.Calibrating the balances is an important step
for measuring sodium carbonate so we know how accurate the balances
are and which balance is better which is the whole point in
calibrating.The more accurate the balances the better it is which further
suggests you will get better results.
For this experiment we used these expensive weights that have been
made to weigh the exact amount to see how accurate balances are.
When calibrating the balance you have to turn the balance on and make
sure you the weight displayed on the balance is at 0 , and put a weight
on the balance every time you measure the weight displayed on the
balance starting from 100 and working your way up and a thing you
must do when you're dealing with more than one weight make sure you
put all the weights at the same time.
The results that i got for calibrating the balances if shown in the following
table:
Weight tested Weight displayed on Difference between
balance the two
100 100.94 0.94
200 203.02 3.02
300 304.76 4.76
400 405.12 5.12
500 505.43 5.43
From this table and results I got i can infer that as there are more weight
being tested there is a bigger weight difference between the two result
so the weight tested and the eight displayed on the balance, this can
further suggest that there will be a bigger percentage different and if
there's more weight added to the balance it will give less accurate and
precise results.
,Cleaning an use of volumetric glassware
Cleaning and use of volumetric glassware is also an important step to
because cleaning equipment and glassware it important because it will
prevent contamination if you don't do this it will affect your results and
observations when your doing an experiment and you will see your
solution contaminated with the chemical/solvent that you have used
before this suggests why it important that that you clean the equipment
properly to prevent this furthermore this can link to accuracy of results if
your equipment is not clean then it will decrease the chances of your
results being accurate which may lead to one of the reasons why you
might anomalous results meaning results which are not close to the
other values when doing repeats as an example.
Using volumetric glassware is a piece of equipment which has markings
which makes measuring the volume of liquids easier. We use these
pieces of equipment because they will provide accurate results because
they have markings in them so you know where to stop when adding a
solution or substance that you want to measure in the volumetric
glassware.
Risk assessment of standard solution
Hazard Possible harm Precaution
Dilute sodium Skin irritation Wear Gloves
carbonate Eye irritant Wear goggles
Broken glassware Can cause cuts and Wear gloves
get into your eye Wear goggles
Spillages Chemicals can get in Tidy workplace
contact with skin
Standardising solution of sodium carbonate
To make a standard solution of sodium carbonate you will have to make
a stock of solution of 250cm3 which has concentration of 0.5 mol
dm-3.Next we will have to calibrate the weighing balance that you will be
using to know which weighing balance is better to use.then you have to
weight approximately the amount anhydrous sodium carbonate that you
, will need and it should be around 1g from the calculated mass for my
results i got 1.4g so this is the value I will using in the calculations.
We then need to transfer the sodium carbonate into a larger beaker
which needs to be done accurately and precisely and make sure all of it
in so we have the same exact and amount and the mass which that
transferred.We then have to add 150cm3 of distilled water into the
beaker and stir it thoroughly until the sodium carbonate is fully
dissolved.We then need to transfer this solution into a 250cm3 flask and
mark where the meniscus is and make sure its labelled and that the
solution is mixed well.We then have to calibrate the pipette to see how
accurate they are and if they work or not.We then need to transfer
25cm3 of sodium carbonate solution using a pipette from the stock
solution the used previously into another 250cm3 volumetric flask .In that
volumetric flask add distilled water and fill it to 250cm3 and making sure
the solution is fully mixed and labelled .We then need to calculate the
exact concentration of the diluted sodium carbonate.
Calculations:
n=mass/Mr
n=1.4/106=0.0132
Mr of Na2CO3= 106
C=n/v
250/1000=0.25
C=0.0132/0.25=0.05mol/dm-3
So the concentration is 0.05col/dm-3
Comparison between a glass stirring rod and a magnetic stirrer
A glass stirring rod and a magnetic stirrer are both equipment that are
used to mix things. A glass stirring rod is made out of glass and it's more
fragile so it can easily break. This can be seen as a risk because it might
cause cuts to the skin and link to why it is important to wear gloves to
minimise this hazard of getting a cut from occurring .
Also it can't mix a solution evenly. A magnetic stirrer is magnetic so it
can stir the solution evenly because its done automatically because it
has a magnetic which prevents human error.I think as magnetic stirrer is
better than a a glass rod because a magnetic stirrer can be left for a
longer period of time without someone tending to it and it's more reliable
because it can automatically be done unlike glass rod someone has to
