Determine the molar mass of the unknown acid.?
A 0.167-g sample of an unknown acid requires 27.8 mL of 0.100 M NaOH to titrate to the equivalence point. Elemental analysis of the acid gives the following percentages by mass: 40.00% C; 6.71% H; 53.29% O.
And the question is?
sorry.
Determine the molar mass of the unknown acid.
Determine the molecular formula of this acid.
To determine the molar mass of the unknown acid, we need to calculate the number of moles of the acid using the titration data and then divide the mass of the acid by the number of moles.
Step 1: Calculate the number of moles of NaOH used in the titration.
We know the volume and concentration of the NaOH solution, so we can use the formula:
Moles of NaOH = Concentration of NaOH (in M) * Volume of NaOH (in L)
Converting the volume to liters:
27.8 mL = 27.8 mL * (1 L / 1000 mL) = 0.0278 L
Substituting the values into the formula:
Moles of NaOH = 0.100 M * 0.0278 L = 0.00278 moles of NaOH
Step 2: Determine the moles of acid that reacted with NaOH.
From the balanced chemical equation for the acid-base reaction, we know that the mole ratio of NaOH to the acid is 1:1. Therefore, the number of moles of acid that reacted is also 0.00278 moles.
Step 3: Calculate the mass of the acid.
To calculate the mass of the acid, we can use the given percentage composition by mass. The sum of the percentages is 100%, so we can assume we have 100 g of the acid.
Mass of C = 40.00% * 100 g = 40.00 g
Mass of H = 6.71% * 100 g = 6.71 g
Mass of O = 53.29% * 100 g = 53.29 g
Total mass of the acid = Mass of C + Mass of H + Mass of O = 40.00 g + 6.71 g + 53.29 g = 100 g
Step 4: Determine the molar mass of the acid.
The molar mass is defined as the mass (in grams) per mole of a substance. We already know the mass and number of moles of the acid, so we can use the formula:
Molar mass = Mass of the acid / Moles of the acid
Molar mass = 100 g / 0.00278 moles of acid
Calculating the molar mass gives us the answer.