If 0.2178 g of a diprotic solid acid is neutralized by 44.81 mL of 0.0953 M NaOH, calculate the molar mass of the solid acid
R(CO2H)2+2NaOH-->R(CO2Na)2+2H2O
Mu(NaOH)=44,81*10^(-3)*0,0953=4,27*10^… mol
Mu(acid)=4,27*10^(-3):2=0,002135 mol
If R=aliphatic saturated rest and there are not other substituents in C-chain,then R=CxH2x and:
0,2178=0,002135(90+12x+2)=0,1964+0,025…
x=(0,2178-0,1964):0,0256=0,84~1
That acid is malonic acid and its molar mass is 104
To find the molar mass of the solid acid, we need to determine the number of moles of the acid that was neutralized.
Step 1: Calculate the number of moles of NaOH used.
We are given the volume (44.81 mL) and concentration (0.0953 M) of NaOH. Using the formula:
number of moles = concentration × volume
number of moles of NaOH = 0.0953 M × 0.04481 L = 0.00426 mol
Step 2: Use the stoichiometry of the reaction to find the number of moles of diprotic acid.
The balanced equation for the reaction between the diprotic acid (HA) and NaOH (OH-) is:
2HA + 2OH- → 2H2O + 2A-
From the equation, we can see that two moles of HA react with two moles of OH-. This means the number of moles of HA is equal to the number of moles of NaOH used.
number of moles of HA = number of moles of NaOH = 0.00426 mol
Step 3: Calculate the molar mass.
We are given the mass of the acid (0.2178 g) and the number of moles of the acid (0.00426 mol). To find the molar mass, we can use the formula:
molar mass = mass / number of moles
molar mass = 0.2178 g / 0.00426 mol
molar mass ≈ 51.11 g/mol
Therefore, the molar mass of the solid acid is approximately 51.11 g/mol.
To calculate the molar mass of the solid acid, we need to first determine the number of moles of the acid that react with the given volume and concentration of NaOH.
Step 1: Calculate the number of moles of NaOH used:
First, convert the given volume of NaOH solution to liters:
44.81 mL = 44.81 / 1000 = 0.04481 L
Next, use the definition of molarity to calculate the number of moles of NaOH:
moles of NaOH = volume (L) × concentration (M)
moles of NaOH = 0.04481 L × 0.0953 M = 0.004274033 moles
Step 2: Determine the number of moles of H+ ions in the diprotic acid:
Since the acid is diprotic, it can donate two moles of H+ ions per mole of acid. Therefore, the number of moles of H+ ions is twice the number of moles of the acid.
moles of acid = moles of H+ ions / 2 = 0.004274033 moles / 2 = 0.0021370165 moles
Step 3: Calculate the molar mass of the diprotic solid acid:
The molar mass is given by the equation:
molar mass = mass (g) / moles
The given mass of the solid acid is 0.2178 g. Thus,
molar mass = 0.2178 g / 0.0021370165 moles ≈ 101.87 g/mol
Therefore, the molar mass of the solid acid is approximately 101.87 g/mol.