Question: How the concentration of acid (HCl) can be determined by titrating it using base (NaOH)?

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Question:

How the concentration of acid (HCl) can be determined by titrating it using base (NaOH)?

Chemicals needed:

  1. Phenolphthalein (color indicator).
  2. Sodium hydroxide (NaOH) concentration of 0.5 molar.
  3. Hydrochloric acid (HCl), with unknown concentration.

Equipments needed:

  1. Flask.
  2. Pipette (uncertainty ±0.05cm3).
  3. Burette (uncertainty ±0.05cm3).
  4. PH meter.
  5. Gloves, lab coat and plastic eye protection.

Steps:

  1. Add a known volume of HCl using pipette in the flask.
  2. Add 2 drops of phenolphthalein in the flask using the pipette.
  3. Shake the flask until the color changes to red.
  4. Start to add NaOH on the HCl, drop by drop.
  5. After each drop shake the flask to accomplish the mixing of the acid with the base.
  6. Take readings of PH value using the PH meter, after each drop.
  7. When HCl color turns to blue, immediately stop adding NaOH, this indicates the neutralization point.
  8. To be sure that HCl is neutralized add few drops of NaOH on HCl.
  9. Repeat the experiment to obtain more accurate data.
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Data collection and processing:

The table below shows the values of PH recorded over the five trials and indicates the neutralization point at a specific volume of NaOH added:

(1.0) table shows the data collected during the trials

Below is the table produced after changing the volume of NaOH to the better measurable unit, also after adding the PH values for each volume added of NaOH then divide them by the number of trials to come out with the average PH value.

(1.1) table showing the processed data

The graph below shows the ...

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