Chemistry Lab Report Template
Name Class Date
Part A — Title, aim and hypothesis
State clearly what you are investigating and what you expect to happen, with a scientific reason.
1.
Title
Determining the concentration of a sodium hydroxide solution by titration with standard hydrochloric acid.
2.
Aim — what will you find out or measure?
To find the concentration (in mol dm−3) of a sodium hydroxide solution by titrating 25.00 cm3 portions against 0.100 mol dm−3 HCl using phenolphthalein indicator.
3.
Hypothesis / prediction (include the balanced equation if there is one)
NaOH(aq) + HCl(aq) → NaCl(aq) + H2O(l). The acid and alkali react in a 1 : 1 mole ratio, so at the end point moles of HCl added = moles of NaOH in the flask. The NaOH is expected to be close to 0.1 mol dm−3, so the titre should be about 25 cm3.
Part B — Apparatus and diagram
List all apparatus with sizes/precision, then draw a labelled diagram of the set-up (use a ruler and pencil; label every piece).
4.
Apparatus list
50.00 cm3 burette (±0.05 cm3) with clamp and stand; 25.00 cm3 volumetric pipette (±0.06 cm3) and pipette filler; 250 cm3 conical flasks ×3; small funnel; white tile; 100 cm3 beakers; wash bottle of distilled water; safety goggles.
5.
Labelled diagram of the apparatus
Model diagram: burette clamped vertically above a conical flask standing on a white tile; labels: burette (HCl, 0.100 mol dm−3), tap, clamp and stand, conical flask (25.00 cm3 NaOH + 3 drops phenolphthalein), white tile.
Part C — Chemicals and hazards (risk assessment)
Complete the risk assessment for every chemical used.
6.
| Chemical (and concentration) | Hazard | Risk | Precaution / control measure |
|---|---|---|---|
| Hydrochloric acid, 0.100 mol dm⁻³ | Low hazard at this concentration (may irritate eyes) | Splashes into eyes when filling the burette | Wear goggles; fill burette below eye level using a funnel; remove funnel before titrating |
| Sodium hydroxide, ≈0.1 mol dm⁻³ | Irritant | Splashes to eyes/skin when pipetting | Wear goggles; use a pipette filler, never mouth-pipette; wash skin with water |
| Phenolphthalein in ethanol | Highly flammable solvent | Ignition near a flame | Keep away from Bunsen burners; use only 2–3 drops |
| Glassware | Broken glass | Cuts if burette or pipette breaks | Clamp burette securely; report and sweep up breakages |
Part D — Method
Write numbered steps in the order you carried them out. Include volumes, concentrations and how you knew the end point was reached.
7.
Method (numbered steps)
1. Rinse the burette with a little 0.100 mol dm−3 HCl, then fill it using a funnel; remove the funnel and run some acid through so the jet is filled. Record the initial reading.
2. Rinse the pipette with NaOH solution, then use a pipette filler to transfer 25.00 cm3 into a conical flask.
3. Add 3 drops of phenolphthalein (pink in alkali).
4. Place the flask on a white tile and add acid while swirling, dropwise near the end point, until the pink colour just disappears (colourless).
5. Record the final burette reading. The first titration is a rough (trial) run.
6. Repeat accurately until at least two titres are concordant (within 0.10 cm3).
2. Rinse the pipette with NaOH solution, then use a pipette filler to transfer 25.00 cm3 into a conical flask.
3. Add 3 drops of phenolphthalein (pink in alkali).
4. Place the flask on a white tile and add acid while swirling, dropwise near the end point, until the pink colour just disappears (colourless).
5. Record the final burette reading. The first titration is a rough (trial) run.
6. Repeat accurately until at least two titres are concordant (within 0.10 cm3).
Part E — Results and observations
Record raw data in the table to the precision of the apparatus (burette readings to 2 d.p., ending in 0 or 5). Tick the concordant titres.
8.
| Rough | Run 1 | Run 2 | Run 3 | |
|---|---|---|---|---|
| Final reading / cm³ | 24.60 | 24.25 | 24.10 | 24.35 |
| Initial reading / cm³ | 0.00 | 0.10 | 0.00 | 0.20 |
| Titre / cm³ | 24.60 | 24.15 | 24.10 | 24.15 |
| Concordant (✓) | ✓ | ✓ | ✓ |
9.
Qualitative observations (colour changes, anything unexpected)
The solution in the flask was pink after adding phenolphthalein; a pink colour that faded on swirling appeared near the end point; at the end point one drop of acid turned the solution colourless. No other changes were seen.
Part F — Calculations and results
Show every step with units. Give the final answer to an appropriate number of significant figures.
10.
Calculations
Mean titre (concordant runs) = (24.15 + 24.10 + 24.15) ÷ 3 = 24.13 cm3
n(HCl) = 0.100 × 24.13/1000 = 2.413 × 10−3 mol
Mole ratio HCl : NaOH = 1 : 1, so n(NaOH) = 2.413 × 10−3 mol
[NaOH] = 2.413 × 10−3 ÷ (25.00/1000) = 0.0965 mol dm−3
n(HCl) = 0.100 × 24.13/1000 = 2.413 × 10−3 mol
Mole ratio HCl : NaOH = 1 : 1, so n(NaOH) = 2.413 × 10−3 mol
[NaOH] = 2.413 × 10−3 ÷ (25.00/1000) = 0.0965 mol dm−3
11.
Final result (value, units, significant figures)
Concentration of NaOH = 0.0965 mol dm−3 (3 s.f.), equivalent to 0.0965 × 40.00 = 3.86 g dm−3.
Part G — Conclusion and evaluation
Answer the aim, compare with your hypothesis, then evaluate the reliability and accuracy of the experiment.
12.
Conclusion — answer the aim using your data.
The sodium hydroxide solution has a concentration of 0.0965 mol dm−3. This supports the prediction that it is close to 0.1 mol dm−3; the 1 : 1 ratio meant the titre (24.13 cm3) was just under 25 cm3.
13.
Sources of error — name random and systematic errors and their effect on the result.
Random: judging the exact end-point colour change and reading the meniscus (±0.05 cm3 per reading, so ±0.10 cm3 per titre ≈ ±0.4 %). Systematic: burette not rinsed with acid (dilutes HCl → titre too large → [NaOH] too high); air bubble in the burette jet; NaOH absorbs CO2 from air, slightly lowering its concentration. Pipette uncertainty ±0.06/25.00 ≈ ±0.24 %.
14.
Improvements — specific changes that would reduce each error.
Rinse burette and pipette with the solutions they will contain; remove air bubbles before the first reading; read the meniscus at eye level; add acid dropwise near the end point and use a white tile; repeat until three titres agree within 0.10 cm3; keep the NaOH stoppered.
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