A 15.00 mL sample of an unknown monoprotic weak acid solution is titrated with 0.35 M NaOH. The initial buret reading is 0.23 mL. The phenolphthalein indicator turns the solution light pink when the buret reads 29.58 mL.

A. what volume of 0.35 M NaOH was delivered?

B. How many moles of NaOH were delivered?

C. How many Moles of weak acid were present in the solution?

D. Calculate the molarity of the unknown weak acid solution

What about this problem troubles you. This is pretty standard; however, the buret reading may be a problem.

29.58 mL is final reading
-0.23 mL is initial reading.
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29.35 ml is titration volume.

B. How many moles of NaOH were delivered?

C. How many Moles of weak acid were present in the solution?

D. Calculate the molarity of the unknown weak acid solution

Can you help me solve those problems as well.

A. To find the volume of 0.35 M NaOH delivered, we subtract the initial buret reading from the final buret reading:

Volume of NaOH delivered = Final buret reading - Initial buret reading
= 29.58 mL - 0.23 mL
= 29.35 mL

Therefore, the volume of 0.35 M NaOH delivered is 29.35 mL.

B. The molarity (M) is defined as moles per liter (mol/L). To find the number of moles of NaOH delivered, we can use the equation Molarity = Moles/Volume.

Moles of NaOH = Molarity × Volume
= 0.35 mol/L × 0.02935 L
= 0.0103 moles

Therefore, 0.0103 moles of NaOH were delivered.

C. The balanced chemical equation for the reaction between the weak acid and NaOH is:

Weak acid + NaOH -> NaA + H2O

From the equation, we can see that 1 mole of weak acid reacts with 1 mole of NaOH. Therefore, the number of moles of the weak acid present in the solution is also 0.0103 moles.

D. To calculate the molarity of the weak acid solution, we need to know the initial volume of the weak acid solution.

If we assume that the initial volume of the weak acid solution is 15.00 mL, then the molarity can be calculated using the equation Molarity = Moles/Volume.

Molarity of weak acid solution = 0.0103 moles / 0.015 L
= 0.687 M

Therefore, the molarity of the unknown weak acid solution is 0.687 M.

To solve this problem, we need to use the concept of stoichiometry, which relates the number of moles of reactants and products involved in a chemical reaction. Here's how you can find the answers to each part of the question:

A. To determine the volume of 0.35 M NaOH delivered, subtract the initial buret reading from the final buret reading. In this case, it is:
Volume = Final buret reading - Initial buret reading
Volume = 29.58 mL - 0.23 mL
Volume = 29.35 mL

B. To find the number of moles of NaOH delivered, multiply the volume of NaOH by the molarity of NaOH. We convert the volume from mL to L by dividing by 1000:
Moles = Volume (in L) * Molarity
Moles = 29.35 mL / 1000 L/mL * 0.35 mol/L
Moles = 0.01027 moles

C. Since it is mentioned that the unknown solution is a monoprotic weak acid, it means that every mole of weak acid reacts with one mole of NaOH. Therefore, the number of moles of weak acid present in the solution is also 0.01027 moles.

D. To calculate the molarity of the unknown weak acid solution, we need to relate the moles of the weak acid to the volume of the solution. In this case, the volume of the unknown weak acid solution is given as 15.00 mL. We convert this to L by dividing by 1000:
Molarity = Moles / Volume (in L)
Molarity = 0.01027 moles / 15.00 mL / 1000 L/mL
Molarity = 0.68533 M

Therefore, the molarity of the unknown weak acid solution is 0.68533 M.