To Find pH Change in Neutralization Reaction (Class 10 Chemistry Practical)
To observe and record pH changes during neutralization of acid and base reaction and determine neutralization point
TL;DR: To observe and record pH changes during neutralization of acid and base reaction and determine neutralization point
Written & reviewed by the Syllab.in Academic Team (CBSE/NCERT subject experts) · Updated
Aim: To observe and record pH changes during neutralization of acid and base reaction and determine neutralization point
Materials Required
- Dilute HCl or other acid
- Dilute NaOH or other base
- Burette and pipette
- pH meter or pH paper
- Beaker or conical flask
- Distilled water
- White tile
- Glass rod
Theory
Neutralization is reaction between acid and base producing salt and water. During neutralization, H+ ions from acid combine with OH- ions from base forming water molecules. pH changes during reaction from acidic to neutral to basic depending on amount of acid or base. At equivalence point pH equals 7 for strong acid and strong base.
Procedure
- Take known volume of dilute HCl in beaker
- Check initial pH using pH meter or paper
- Record initial pH value
- Add dilute NaOH using burette in small aliquots
- Stir well with glass rod after each addition
- Measure pH after each addition of NaOH
- Continue adding NaOH until pH becomes 7
- Record volume of NaOH added at each step
- Note the neutralization point where pH changes sharply
- Plot graph of pH versus volume of base added
Observation
Initial pH around 1 for dilute HCl. pH increases gradually with base addition. Near equivalence point pH increases sharply. Equivalence point occurs around pH 7. After equivalence point pH increases slowly to basic region.
Result
pH curve plotted showing neutralization process. Equivalence point determined. Sharp pH change region identified indicating neutralization.
Precautions
- Use freshly prepared solutions for accurate measurements
- Calibrate pH meter before use
- Stir thoroughly after each addition for uniform mixing
- Use small aliquots of base near neutralization point
- Ensure electrodes are clean and in solution properly
Viva Questions
What is pH scale?
pH scale is logarithmic scale from 0 to 14 measuring hydrogen ion concentration. pH 7 is neutral, less than 7 is acidic, more than 7 is basic.
What happens during neutralization reaction?
During neutralization, H+ ions from acid combine with OH- ions from base to form water: H+ + OH- gives H2O.
What is equivalence point in titration?
Equivalence point is point where acid and base have reacted completely in stoichiometric ratio to form salt and water.
Why does pH change sharply near equivalence point?
Near equivalence point, very small addition of base causes large pH change because very few H+ ions remain to buffer the pH.
What is the pH at equivalence point for strong acid and strong base?
For strong acid and strong base neutralization, pH at equivalence point is 7 (neutral) because salt formed does not hydrolyze.
Why is the graph curve shaped that way?
Graph shows gradual pH increase initially, then sharp vertical rise near equivalence point, then gradual increase at higher pH. This shape is characteristic of acid-base titration.
More Class 10 Chemistry Practicals
- To Prepare a True Solution and Observe the Tyndall Effect
- To Find the pH of Samples Using Indicators
- To Study a Double Displacement (Precipitation) Reaction
- To Test Acids and Bases with Indicators
- To Verify the Law of Conservation of Mass
- To Study the Effect of Temperature on Reaction Rate
🤖 Stuck on any of these? Ask Syllab's free AI Tutor to explain step by step →