This document contains information about strong and weak acids, and procedures for acid-base titration experiments and standard solution preparation: 1) Hydrochloric acid is a strong acid that fully ionizes in water, giving it a low pH of 1. Methanoic acid is a weak acid that only partially ionizes, resulting in its higher pH of 4. 2) An experiment is described to determine the endpoint of a titration between potassium hydroxide and hydrochloric acid solutions. 3) Instructions are provided for preparing a 0.1 M sodium hydroxide standard solution and calculating concentrations using molarity and dilution equations.

1. Rossita Radzak : SASER
ACID - BASES
The pH value of 1.0 mol dm-3 hydrochloric acid is 1
The pH value of 1.0 mol dm-3 methanoic acid is 4
Explain why these two solutions have different pH values.
 identify strong acid , weak acid
 definition strong acid
 definition weak acid
 relationship between pH value and concentration of hydrogen ions
Sample answer:
1. Hydrochloric acid is a strong acid while methanoic acid is a weak acid.
2. Hydrochloric acid completely ionizes in water to form high concentration of hydrogen
ions.
HCl + H2O  H3O+ + Cl- // HCl  H+ + Cl- , H3O+ , hydroxonium ion
3. methanoic acid ionizes partially in water to form low concentration hydrogen ions
CH3COOH  CH3COO- + H+
4. the higher the concentration of hydrogen ions the lower the pH value.
Aim :To determine the end point during the neutralization of potassium hydroxide
and hydrochloric acid
Apparatus : 25 cm3 pipette, burette , 250 cm3 conical flask, retort stand, white tile
Material : potassium hydroxide and hydrochloric acid 0.1 mol dm-3 , phenolphathalein.
Procedure:
1. Rinse a burette with a small amount hydrochloric acid 0.1 mol dm-3 .
2. Clamp the burette on retort stand.
3. Fill the burette with hydrochloric acid 0.1 mol dm-3 .Adjust the meniscus level of acid to a
reading at 0.
4. Record the initial burette reading.
5. Pipette 25.0 cm3 of potassium hydroxide 0.1 mol dm-3 into conical flask.
6. Add two drop of phenolphathalein.
7. Add hydrochloric acid 0.1 mol dm-3 carefully. Swirl the conical flask during the process.
8. When the colour of the mixture turn paler, add hydrochloric acid drop by drop.
9. Stop adding the hydrochloric acid as soon as the solution turns colourless.
10. Record the final burette reading.
11. Repeat steps 1-10 twice. Tabulate your reading.
Result :
Titration 1 2 3
Final burette reading, cm3
Initial burette reading, cm3
Volume of hydrochloric acid 0.1 mol dm-3 , cm3
1

2. Rossita Radzak : SASER
Preparation Standard solution ( 0.1 mol dm-3 NaOH, 100 cm3)
1. calculate the mass of solute ( mole = 0.1 x 100/1000 , 0.01 = mass/ 40)
2. weigh 0.4g of NaOH in weighing bottle using digital balance / electronic balance
3. pour into a beaker, rinse the bottle with distilled water.
4. dissolve NaOH with a little ( 10 – 20 cm3 )distilled water.
5. transfer the mixture into volumetric flask 100 cm3 rinse the beaker with distilled water.
6. pour the washings into volumetric flask 100 cm3
7. add distilled water, shake well
8. add distilled water drop by drop to finally bring the volume of solution to the 100 cm3
mark / calibration mark.
Preparation of a standard solution by dilution method
M1V1 = M2V2
M1 – initial molarity
V1 - initial volume
M2 – final molarity
V2 – final volume
NOTE : CONCENTRATION – 1. MOLARITY - mol dm-3
2. g dm-3
2