20cm of sulphuric acid required 18.5cm of 0.1M sodium hydroxide solution for complete neutralisation.
To understand this problem, we need to use the concept of neutralization reactions and stoichiometry. In a neutralization reaction, an acid reacts with a base to form a salt and water.
The balanced chemical equation for the neutralization reaction between sulfuric acid (H2SO4) and sodium hydroxide (NaOH) is:
H2SO4 + 2 NaOH -> Na2SO4 + 2 H2O
From the equation, we can see that one mole of sulfuric acid reacts with two moles of sodium hydroxide to produce one mole of sodium sulfate and two moles of water.
Given that the volume of the sodium hydroxide solution used is 18.5 cm³, we need to determine the volume of the sulfuric acid required for complete neutralization.
Step 1: Convert the volume of sodium hydroxide solution to moles.
We know that the concentration of the sodium hydroxide solution is 0.1 M (moles per liter).
Using the formula:
moles = concentration (M) x volume (L)
We need to convert the volume from cm³ to liters. Since 1 cm³ = 0.001 L, the volume becomes 0.0185 L.
moles of NaOH = 0.1 M x 0.0185 L = 0.00185 moles
Step 2: Use the stoichiometry from the balanced equation to determine the moles of sulfuric acid.
From the balanced equation, we know that the ratio of sulfuric acid to sodium hydroxide is 1:2. Therefore, the moles of sulfuric acid required will be twice the moles of sodium hydroxide.
moles of H2SO4 = 2 x moles of NaOH
= 2 x 0.00185 moles
= 0.0037 moles
Step 3: Convert moles of sulfuric acid to volume.
To convert moles of sulfuric acid to volume, we need to know its concentration (Molarity). If the concentration is provided, we can use the formula:
moles = concentration (M) x volume (L)
As the concentration of sulfuric acid is not given in the problem statement, we cannot directly convert moles to volume without this information.
Therefore, it is not possible to determine the volume of sulfuric acid required for complete neutralization without the concentration of the acid.