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8.1Laboratory Skills

Practical technique and safety — EST 2 Chemistry Revision Notes & Topical Questions

5 min read 8 parts Lesson 1 of 2 1 quiz

📚 EST 2 Chemistry Hub / Topical Revision
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Curriculum Equation Key قوانين الرقم الهيدروجيني والاتزان الأيوني - pH & Acid-Base Equilibrium FormulasFast Exam Solution
pH = -log[H⁺] | pOH = -log[OH⁻] | pH + pOH = 14 | [H⁺][OH⁻] = 10⁻¹⁴
Word Equation & Conditions: الرقم الهيدروجيني = -لوغاريتم تركيز أيون الهيدروجين | pH + pOH = 14
Location & Specifications: الاتزان الأيوني، كيمياء 3 ثانوي، التحصيلي، و AP Chemistry.
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Lesson summary

Practical technique and safety EST Chemistry notes: Select appropriate laboratory equipment.Multiplication/divisionanswer has the fewest significant figures.Addition/subtractionanswer has the fewest decimal places.Random errors affect precision; systematic errors affect accuracy.…

  • Measured density 2.60 g/cm³; accepted 2.70. Percent error?
  • 12.11 + 18.0 + 1.013 = ?
  • Practical technique and safety EST Chemistry: what to do next
  • Volumetric pipette
  • Identify / Describe (FRQ)
  • Explain / Justify (FRQ)

Part 1 of 8Key ideas

Multiplication/division
Multiplication/division answer has the fewest significant figures.
Addition/subtraction
Addition/subtraction answer has the fewest decimal places.
Random errors affect precision; systematic errors affect accuracy.
Always wear goggles and a lab coat.
Never return unused reagent to the stock bottle.

Part 2 of 8Learning objectives

Learning objectives
Select appropriate laboratory equipment.
Apply safety procedures.
Handle significant figures and errors.

Part 3 of 8Essential knowledge

Hazard symbols indicate flammable, toxic, corrosive, oxidising.
Rinse burette with the solution it will hold.
Titrations are repeated until concordant (within 0.10 mL).
Independent variable is changed; dependent variable is measured.
Graphs
Graphs independent variable on x-axis.

Part 4 of 8Process & sequence

1
Plan: identify variables and controls.
2
Choose equipment matched to the needed precision.
3
Record raw data with units and correct sig figs.
4
Repeat trials and average.
5
Calculate and evaluate errors.

A reliable experimentwrite these steps in this order; each step is a marking point.

  1. Plan variables
  2. Choose equipment
  3. Measure carefully
  4. Repeat
  5. Evaluate error

Part 5 of 8Worked examples

1Measured density 2.60 g/cm³; accepted 2.70. Percent error?
  • 0.10 ÷ 2.70 × 100 = 3.7%.
212.11 + 18.0 + 1.013 = ?
  • 31.123 → 31.1 (one decimal place).

Part 6 of 8Summary

Summary
Accuracy = near true value; precision = repeatable.
Read meniscus at eye level.
Add acid to water.

Part 7 of 8Keep going

Practical technique and safety EST Chemistry: what to do next

These Practical technique and safety EST Chemistry notes covered the key ideas, worked examples and exam technique for this topic. Check your Practical technique and safety EST Chemistry understanding with the practice questions below, then reread any Practical technique and safety EST Chemistry point you were unsure about before moving on.

1
Practice: Practical technique and safety EST Chemistry practice questions
2
Previous lesson: 7.3 Environmental chemistry
3
Next lesson: 8.2 Separation and analysis
4
Course: EST 2 Chemistry — all units
5
Official syllabus: OpenStax free science textbooks

Practical technique and safety EST Chemistry revision notes

Part 8 of 8Compare: Compare

Choosing glassware
TaskBest equipment
Approximate volumeBeaker or measuring cylinder
Exact fixed volumeVolumetric pipette
Variable volume in titrationBurette
Preparing standard solutionVolumetric flask
Heating a solid stronglyCrucible
MassAnalytical balance
Safety rules
SituationCorrect action
Diluting acidAdd acid to water slowly
Chemical in eyesEyewash for 15 minutes
Heating test tubePoint away from people
Smelling a gasWaft toward nose
Spill of acidNeutralise with NaHCO3, then clean
Flammable solventNo open flames
Significant figure rules
NumberSig figs
0.004503
12002 (ambiguous)
1.200 × 1034
1013

Key terms

Command terms

Command terms
Identify / Describe (FRQ)
A short, specific statement; describing requires relevant characteristics, not a single word.
Explain / Justify (FRQ)
Give the cause-and-effect reasoning or evidence; a restated fact does not score.
Calculate
Show setup, substitution and the answer with units.
Predict
State the expected outcome; add a reason only if asked to justify.
MCQ technique
Read every option; eliminate distractors that are true statements but do not answer the question; watch for NOT/EXCEPT.

Exam technique

Keywords the mark scheme looks for in this lesson

Keywords the mark scheme looks for in this lesson
Accuracy · Precision · Significant figures · Percent error · Meniscus · Burette · Volumetric pipette · Fume hood
Learn each definition in the Key words tab exactly; a missing keyword in a definition usually loses the mark.

How to get full marks (examiner guidance)

1
Answer exactly what is asked; extra correct material does not earn credit, and contradictory statements can cancel credit (AP FRQ).
2
Use precise vocabulary (e.g. “active site”, “concentration gradient”, “allele”), never “it/stuff/things”.
3
Show units and working in calculations.
4
In MCQs, predict the answer before reading the options, then eliminate.

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