when a solution prepared by dissolving 4.00g of an unknown monoprotic acid in 1.00L of water is titrated with 0.600M NaOH, 38.7mL of the NaOH solution is needed to neutralize the acid. What was the molarity of the acid solution? what is the molecular weight of the unknown acid?
HA is the acid.
HA + NaOH ==> NaA + H2O
moles NaOH = M x L = 0.6000 x 0.0387 = 0.02322.
Therefore, moles HA = 0.02322
M of HA = moles/L.
moles = grams/molecular weight
m.w. = grams/moles = 4/0.02322 = ?? Then round to 3 significant figures (based on the 38.7)
To find the molarity of the acid solution, you can use the equation:
M1V1 = M2V2
Where M1 is the molarity of the acid solution, V1 is the volume of the acid solution (in liters), M2 is the molarity of the NaOH solution, and V2 is the volume of the NaOH solution used in the titration (in liters).
In this case, M2 is given as 0.600M and V2 is given as 38.7mL, which needs to be converted to liters by dividing by 1000:
V2 = 38.7mL / 1000 = 0.0387L
We'll substitute the known values into the equation:
M1 * 1.00L = 0.600M * 0.0387L
Simplifying the equation:
M1 = (0.600M * 0.0387L) / 1.00L
M1 = 0.02322M
Therefore, the molarity of the acid solution is 0.02322M.
To find the molecular weight of the unknown acid, you can use the equation:
Molecular weight = (Mass of the acid) / (Number of moles of the acid)
In this case, the mass of the acid is given as 4.00g. To find the number of moles of the acid, you can use the equation:
Number of moles = Mass of the acid / Molar mass of the acid
We already know the mass of the acid, so we need to calculate the molar mass of the acid. Since we know it is a monoprotic acid, it donates only one proton in a reaction.
Let's assume the acid formula is HA.
The molar mass of HA can be calculated using the equation:
Molar mass = (Mass of Hydrogen + Mass of A)
Assuming the atomic mass of hydrogen (H) is 1.01 g/mol and the atomic mass of A can be calculated using the periodic table.
Once you calculate the molar mass, you can substitute the values into the equation:
Number of moles = 4.00g / Molar mass
Finally, substitute the value of the number of moles into the equation for molecular weight:
Molecular weight = 4.00g / Number of moles
By going through this process, you will be able to calculate the molecular weight of the unknown acid.