step J pour the potassium hydroxide solution into a conical flask and add a few drops of indicator to this solution step K fill a burette with dilute hydrochloric acid and record the initial reading from the burette step L use a measuring cylinder to obtain 25 cm³ of potassium hydroxide solution step M take a final reading from the burette and calculate the volume of the dilute hydrochloric acid reacted step N run the dilute hydrochloric acid from the burette into the conical flask until the indicator changes colour (i) Write the steps in the correct order - Edexcel - GCSE Chemistry - Question 4 - 2020 - Paper 1

A volumetric pipette can be used to accurately measure 25.0 cm³ of potassium hydroxide solution.

The new mixture was evaporated because it was reacted with a fresh sample of potassium hydroxide, ensuring no indicator was present. The original mixture from the titration contains an indicator, which would contaminate the salt, leading to impure potassium chloride.

The percentage yield is calculated using the formula:

ext{Percentage Yield} = rac{ ext{Actual Yield}}{ ext{Theoretical Yield}} imes 100

Substituting the values, we get: ext{Percentage Yield} = rac{0.84 ext{ g}}{0.70 ext{ g}} imes 100 = 120\%.

The actual yield was greater than the theoretical yield because the product may have retained some water, meaning not all mass loss was due to the evaporation of potassium chloride.

To calculate the atom economy, we use the formula:

ext{Atom Economy} = rac{ ext{Molar mass of desired product}}{ ext{Total molar mass of reactants}} imes 100

The molar mass of potassium chloride (KCl) is 74.5 g/mol. The total molar mass of the reactants KOH and HCl is:

$56.0 + 36.5 = 92.5 ext{ g/mol}$

Thus, the atom economy is:

ext{Atom Economy} = rac{74.5}{92.5} imes 100 = 80.5\%.