Electrolysis

The reaction for the electrolysis of water is: From this reaction, it is clear that 1 mole of O is released for every 4 moles of electrons (since 4 moles of electrons are required to produce 2 moles of H and 1 mole of O ). Step 1: Calculate moles of O liberated The volume of O is given as 100 ml at standard conditions (STP). At STP, 1 mole of any gas occupies 22.4 liters (or 22400 ml). Therefore, the moles of O liberated are: Step 2: Calculate the total charge required From the reaction, we know that for every 1 mole of O , 4 moles of electrons are involve(D) The total moles of electrons required to liberate 4.464 × 10 mol of O is: The charge required to produce 1 mole of electrons is 96500 C (Faraday constant). Therefore, the total charge required is: Step 3: Calculate the current The total charge is released in 2 hours (or 7200 seconds). Using the relation , where is the current and is the time, we can calculate the current: Thus, the required current is 0.2393 (A)

To calculate the time required to obtain a pH of 4 from a 0.1 M NaOH solution by electrolysis, we need to follow these steps:

Hence, the time required to reach the target pH of 4 is approximately 1.93 s. The correct option is 1.93 s.