A sample of hydrogen chloride gas was dissolved in water to make 250cm³HCl solution.25 cm³ of the solution required 46 cm³ of 1.1M sodium hydroxide for complete neutralisation.Calculate
a)the number of moles of hydrochloric acid in 25 cm³
b) Determine the mass of hydrogen chloride that was dissolved to make 250cm³of solution
a) To calculate the number of moles of hydrochloric acid in 25 cm³, we first need to determine the concentration of the HCl solution.
We know that 25 cm³ of the HCl solution required 46 cm³ of 1.1M sodium hydroxide for complete neutralization. This means that the concentration of HCl is equal to the concentration of NaOH.
Therefore, the concentration of HCl is also 1.1M.
To calculate the number of moles, we use the equation:
moles = concentration × volume
moles = 1.1 M × 25 cm³ = 27.5 mmol
So, there are 27.5 millimoles (mmol) of hydrochloric acid in 25 cm³ of the solution.
b) To determine the mass of hydrogen chloride dissolved, we need to convert the moles of HCl to grams using the molar mass.
The molar mass of HCl is 36.46 g/mol (1 hydrogen atom = 1.01 g/mol, 1 chlorine atom = 35.45 g/mol).
mass = moles × molar mass
mass = 27.5 mmol × 36.46 g/mol = 1002.65 mg
Since 1 g = 1000 mg, the mass of hydrogen chloride dissolved is 1.00265 grams.