0.250g of phthalic acid is dissolved in 40.00cm^3 of 0.100 mol dm^-3 NaOH. It requires 11.80 cubic centimeters of 0.100 mol\dm^-3 HCL fo neutralisation( to phenolphthalein) The mole ratio in which phthalic acid reacts with sodium hydroxide ihn 1:2
(a) Calculate the moles of excess NaOH reacted with HCL
(b)Calculate the moles of phthalic acid used
(c) Calculate the molecular mass of phthalic acid
0.250 g of phthalic acid is dissolved in 40.00 cm3 of 0.100 mol dm-3 NaOH. It
requires 11.80 cm3 of 0.100 mol dm-3 HCl for neutralisation (to
phenolphthalein). The mole ratio in which phthalic acid reacts with sodium
hydroxide is 1:2.
What's the answers for the question?
Students
To calculate the moles of excess NaOH reacted with HCl (a):
1. Start by calculating the moles of HCl used in the reaction using the given volume and concentration of HCl.
Moles of HCl = (Volume of HCl used in dm^3) x (Concentration of HCl in mol/dm^3)
In this case, the volume of HCl used is given as 11.80 cm^3, which is equivalent to 11.80/1000 dm^3. The concentration of HCl is given as 0.100 mol/dm^3.
Moles of HCl = (11.80/1000) dm^3 x 0.100 mol/dm^3
2. Since the reaction between phthalic acid and NaOH occurs in a 1:2 ratio, the moles of NaOH reacted with HCl will be double the moles of HCl used.
Moles of NaOH reacted with HCl = 2 x Moles of HCl
To calculate the moles of phthalic acid used (b):
1. Use the mole ratio given in the question, which states that the mole ratio between phthalic acid and NaOH is 1:2.
Moles of phthalic acid used = Moles of NaOH reacted with HCl / 2
To calculate the molecular mass of phthalic acid (c):
1. Calculate the moles of phthalic acid using the above formula (b).
Moles of phthalic acid = Moles of phthalic acid used
2. Calculate the molecular mass using the formula:
Molecular mass of phthalic acid = Mass of phthalic acid / Moles of phthalic acid
Given that the mass of phthalic acid is 0.250g, and the molecular mass will be in g/mol, you can substitute these values into the formula to get the answer.