Concentrate on keeping your standards:
Experiment 1: preparation of a standard solution
Calibration: Calibration is used to accurately measure equipment by comparing it to its standard
measurement.
Make sure the balance is level
Then switch the instrument on.
The balance will flash with 8.8.8.8.8.8.8.
The display should then appear with the figure 0.00g
Allow it to stabilise for 15-20 seconds and then begin placing the weights (0.1g, 1g, 10g and 100g)
for calibration.
Place each weight
record the result
record observations
repeat the steps 5-6 times
calculate standard deviation
measurement uncertainty=Standard deviation * 2/Actual Mass Value
When weighing we used an analytical weighing balance to obtain a more accurate reading. It
outputs the weight to 3.D.P.
When doing the calibration using plastic forceps helps to obtain a more accurate reading. Using
fingers will put oil onto the Weight; this will tamper our end result.
Our display was not stable so we had to press the TARE key and wait till the display showed 0.00g.
This slowed us down when calibrating.
Calibration weight (g) Actual weight difference Maintenance and
adjustments
0.1000 0.1 0
1.0000 1 0
10.0001 10 0.0001
100.0002 100 0.0002
Procedure:
Calibrate the balance.
Then we need to accurately weigh out the solute that is going to make up our standard solution.
Get the balance and set a weighing boat on the balance, next zero the balance. Weigh out 2.650g of
anhydrous sodium carbonate. (Na2CO3). After we get distilled water (deionised) and wash down the
Na2CO3 from the weighing boat into a beaker that has 100cm³ of distilled water. To help dissolve
the solute, stir with a glass rod.
Carefully transfer the solution to a 250cm³ volumetric flask using the help of a funnel.
Rinse down the stirring rod, funnel and the beaker with distilled water into the volumetric flask to
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, ensure every drop of the Na2CO3 has made it into the flask.
Add distilled water into the flask till it reaches the 250cm³ mark.
Read the value at eye level to obtain a more accurate reading.
Make sure the solute is at the meniscus.
Place the stopper on the flask and invert the flask more then 8-10 times to ensure you get a secure
that we get a homogenous solution.
This is a fundamental step when carrying out titration.
Swirling and shaking the flask will not allow us to obtain a homogenous solution due to the shape of
the flask.
A homogenous is a mixture that where the products have been completely dissolved and distributed
evenly throughout the solute
Label the flask with what the solution is, and with the molar mass. (0.100)
Health and safety:
-Confirm you are not allergic to any of the substances which you are going to be using
-Have on goggles, so unwanted substances cannot go into your eyes such as the solute Na2CO3
going into your eye. Glass equipment could also smash and shatter, small shards of glass could go
into your eye. Wearing goggles prevents this.
-Wear a lab coat so you can avoid and spills, staining or corrosive substances going onto your
skin/clothes. -
Wear gloves so the hands are protected from the substances, this helps avoid contamination and
infections.
-Keep bags and paper work away from the work area as it is an obstruction and you could fall.
-Tuck in chairs and keep them out of the way.
-Never chew gum, eat, drink or keep these on the work surface as the substances can contaminate
your food.
-Don’t apply any sort of cosmetics or lip balm as again you can consume the solutes
-Be aware of where all safety appliances are for examples: eye wash, fire extinguisher, fire exit...
-Correctly dispose of the equipment and put the used equipment that cannot be disposed of away in
its proper area/place which you have been instructed to place leave the equipment
Results Table:
Mass of weighing boat 2.078g
Mass of weighing boat + Na2CO3 4.73
Mass(m) of Na2CO3 used 2.652
Relative molecular mass (Mr) of Na2CO3 106g
Moles (n) of Na2CO3 = m/Mr 0.025 mol
Volume of solution V1 250cm3
Volume of solution V2 0.250dm3
Concentration of Na2CO3 = n/V2 0.100mol dm-3
(M)
Calculations:
Mass of Na2Co3-> 4.73-2.078=2.652
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Experiment 1: preparation of a standard solution
Calibration: Calibration is used to accurately measure equipment by comparing it to its standard
measurement.
Make sure the balance is level
Then switch the instrument on.
The balance will flash with 8.8.8.8.8.8.8.
The display should then appear with the figure 0.00g
Allow it to stabilise for 15-20 seconds and then begin placing the weights (0.1g, 1g, 10g and 100g)
for calibration.
Place each weight
record the result
record observations
repeat the steps 5-6 times
calculate standard deviation
measurement uncertainty=Standard deviation * 2/Actual Mass Value
When weighing we used an analytical weighing balance to obtain a more accurate reading. It
outputs the weight to 3.D.P.
When doing the calibration using plastic forceps helps to obtain a more accurate reading. Using
fingers will put oil onto the Weight; this will tamper our end result.
Our display was not stable so we had to press the TARE key and wait till the display showed 0.00g.
This slowed us down when calibrating.
Calibration weight (g) Actual weight difference Maintenance and
adjustments
0.1000 0.1 0
1.0000 1 0
10.0001 10 0.0001
100.0002 100 0.0002
Procedure:
Calibrate the balance.
Then we need to accurately weigh out the solute that is going to make up our standard solution.
Get the balance and set a weighing boat on the balance, next zero the balance. Weigh out 2.650g of
anhydrous sodium carbonate. (Na2CO3). After we get distilled water (deionised) and wash down the
Na2CO3 from the weighing boat into a beaker that has 100cm³ of distilled water. To help dissolve
the solute, stir with a glass rod.
Carefully transfer the solution to a 250cm³ volumetric flask using the help of a funnel.
Rinse down the stirring rod, funnel and the beaker with distilled water into the volumetric flask to
1|Page
, ensure every drop of the Na2CO3 has made it into the flask.
Add distilled water into the flask till it reaches the 250cm³ mark.
Read the value at eye level to obtain a more accurate reading.
Make sure the solute is at the meniscus.
Place the stopper on the flask and invert the flask more then 8-10 times to ensure you get a secure
that we get a homogenous solution.
This is a fundamental step when carrying out titration.
Swirling and shaking the flask will not allow us to obtain a homogenous solution due to the shape of
the flask.
A homogenous is a mixture that where the products have been completely dissolved and distributed
evenly throughout the solute
Label the flask with what the solution is, and with the molar mass. (0.100)
Health and safety:
-Confirm you are not allergic to any of the substances which you are going to be using
-Have on goggles, so unwanted substances cannot go into your eyes such as the solute Na2CO3
going into your eye. Glass equipment could also smash and shatter, small shards of glass could go
into your eye. Wearing goggles prevents this.
-Wear a lab coat so you can avoid and spills, staining or corrosive substances going onto your
skin/clothes. -
Wear gloves so the hands are protected from the substances, this helps avoid contamination and
infections.
-Keep bags and paper work away from the work area as it is an obstruction and you could fall.
-Tuck in chairs and keep them out of the way.
-Never chew gum, eat, drink or keep these on the work surface as the substances can contaminate
your food.
-Don’t apply any sort of cosmetics or lip balm as again you can consume the solutes
-Be aware of where all safety appliances are for examples: eye wash, fire extinguisher, fire exit...
-Correctly dispose of the equipment and put the used equipment that cannot be disposed of away in
its proper area/place which you have been instructed to place leave the equipment
Results Table:
Mass of weighing boat 2.078g
Mass of weighing boat + Na2CO3 4.73
Mass(m) of Na2CO3 used 2.652
Relative molecular mass (Mr) of Na2CO3 106g
Moles (n) of Na2CO3 = m/Mr 0.025 mol
Volume of solution V1 250cm3
Volume of solution V2 0.250dm3
Concentration of Na2CO3 = n/V2 0.100mol dm-3
(M)
Calculations:
Mass of Na2Co3-> 4.73-2.078=2.652
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