Unit 2 Assignment
Part 1 - Preparation of a Standard solution
A standard solution is a solution which contains a precisely known
concentration of an element or a substance.
Equipment:
- Weighing balance
- Anhydrous sodium carbonate
- Large beaker
- 150cm³ distilled water
- Weighing boat
- Stirring rod
- 250cm³ volumetric flask
Method:
- First of all, calibrate the weighing balance by pressing start and checking that
the reading is zero.
- Place the weighing boat onto the weighing balance to calibrate it, by recording
the mass which should be zero.
- After, place the anhydrous sodium carbonate into the weighing boat between
1.25g and 1.45g.
- Transfer the sodium carbonate into a large beaker and record the mass
transferred.
- Add 150cm ³ of distilled water into the beaker, and stir the sodium carbonate
to dissolve it.
- Transfer the sodium carbonate solution to a 250cm ³ volumetric flask using a
funnel, and make up the solution to 250cm³ with more distilled water.
- Place a thumb over the top of the volumetric flask and mix the solution 3
times, holding it up and down.
Results table:
Mass of weighing boat (g) 1.59g
Mass of Na²CO³ (g) 1.36g
, Mass of weighing boat + residue (g) 1.59 + 1.36 = 2.95g
Calculation:
Find the concentration of Na₂CO₃:
X= Mass of Na₂CO₃
Y = Mr of Na₂CO₃
Mass of Na₂CO₃ used = 1.36g
Mr of Na₂CO₃ = (23 X 2) + 12 + (16 X 3)
Y = 106
Moles of Na₂CO₃ = x ÷ y
= 1.36 ÷ 106 = 0.013 (3d.p.)
Concentration of Na₂CO₃ = mole ÷ volume
Mole = 0.013mol
Volume = 250cm³
cm³ ÷ 1000 = dm³
250 ÷ 1000 = 0.25dm³
0.013 ÷ 0.25 = 0.052dm³
Concentration of Na₂CO₃ = 0.052dm³
Evaluation:
In conclusion, the method used to prepare a standard solution of sodium carbonate
seems reliable as the readings collected for the mass of Na²CO³ held a high level of
accuracy as they were close to the given range of between 1.25 and 1.45g. Also, to
ensure that the method held a high level of accuracy, the weighing balance and the
weighing boat were both calibrated at the beginning of the experiment inorder to
avoid zero error as this would affect the results by giving a false reading. However,
Part 1 - Preparation of a Standard solution
A standard solution is a solution which contains a precisely known
concentration of an element or a substance.
Equipment:
- Weighing balance
- Anhydrous sodium carbonate
- Large beaker
- 150cm³ distilled water
- Weighing boat
- Stirring rod
- 250cm³ volumetric flask
Method:
- First of all, calibrate the weighing balance by pressing start and checking that
the reading is zero.
- Place the weighing boat onto the weighing balance to calibrate it, by recording
the mass which should be zero.
- After, place the anhydrous sodium carbonate into the weighing boat between
1.25g and 1.45g.
- Transfer the sodium carbonate into a large beaker and record the mass
transferred.
- Add 150cm ³ of distilled water into the beaker, and stir the sodium carbonate
to dissolve it.
- Transfer the sodium carbonate solution to a 250cm ³ volumetric flask using a
funnel, and make up the solution to 250cm³ with more distilled water.
- Place a thumb over the top of the volumetric flask and mix the solution 3
times, holding it up and down.
Results table:
Mass of weighing boat (g) 1.59g
Mass of Na²CO³ (g) 1.36g
, Mass of weighing boat + residue (g) 1.59 + 1.36 = 2.95g
Calculation:
Find the concentration of Na₂CO₃:
X= Mass of Na₂CO₃
Y = Mr of Na₂CO₃
Mass of Na₂CO₃ used = 1.36g
Mr of Na₂CO₃ = (23 X 2) + 12 + (16 X 3)
Y = 106
Moles of Na₂CO₃ = x ÷ y
= 1.36 ÷ 106 = 0.013 (3d.p.)
Concentration of Na₂CO₃ = mole ÷ volume
Mole = 0.013mol
Volume = 250cm³
cm³ ÷ 1000 = dm³
250 ÷ 1000 = 0.25dm³
0.013 ÷ 0.25 = 0.052dm³
Concentration of Na₂CO₃ = 0.052dm³
Evaluation:
In conclusion, the method used to prepare a standard solution of sodium carbonate
seems reliable as the readings collected for the mass of Na²CO³ held a high level of
accuracy as they were close to the given range of between 1.25 and 1.45g. Also, to
ensure that the method held a high level of accuracy, the weighing balance and the
weighing boat were both calibrated at the beginning of the experiment inorder to
avoid zero error as this would affect the results by giving a false reading. However,
