A 25.0 mL sample of NaHSO4(aq) was titrated with 0.500 mol/L NaOH(aq) using phenolphthalein indicator. At the endpoint, one drop of NaOH(aq) was sufficient to change the phenolphthalein indicator from colourless to pink. To reach this point, 10.2 mL of NaOH(aq) had been added. What is the concentration of the NaHSO4(aq)?

Question

A 25.0 mL sample of NaHSO4(aq) was titrated with 0.500 mol/L NaOH(aq) using phenolphthalein indicator. At the endpoint, one drop of NaOH(aq) was sufficient to change the phenolphthalein indicator from colourless to pink. To reach this point, 10.2 mL of NaOH(aq) had been added. What is the concentration of the NaHSO4(aq)?

Answer 1

Please show all work. I’m very confused with this question

Answer 2

No need to be confused. Reactions reach the end point when mols of one = mol equivalent of the other. So how many millimoles (1000*mols) NaOH were added. That's mL x M = millimols = 10.2 mL x 0.500 = 5.1

So you have 5.1 millimols NaHSO4 in that sample. It was in 25.0 mL so the concentration in millimols/mL = mols/L = M = 5.1 mmols/25.0 mL = ?

Answer 3

To calculate the concentration of NaHSO4(aq), you can use the concept of stoichiometry and the volume of NaOH(aq) used during the titration.

Step 1: Write the balanced chemical equation for the reaction between NaHSO4(aq) and NaOH(aq):

NaHSO4(aq) + NaOH(aq) -> Na2SO4(aq) + H2O(l)

This equation tells us that the reaction occurs in a 1:1 ratio between NaHSO4 and NaOH.

Step 2: Determine the moles of NaOH used in the titration:

Since the volume of NaOH used is 10.2 mL and the concentration of NaOH is 0.500 mol/L, we can calculate the moles of NaOH used as follows:

Moles of NaOH = Volume of NaOH (L) x Concentration of NaOH (mol/L)
= 10.2 mL x (1 L/1000 mL) x 0.500 mol/L
= 0.00510 mol

Step 3: Use the stoichiometry of the balanced equation to determine the moles of NaHSO4:

From the balanced equation, we know that the reaction occurs in a 1:1 ratio between NaHSO4 and NaOH. Therefore, the moles of NaHSO4 are also 0.00510 mol.

Step 4: Calculate the concentration of the NaHSO4(aq):

The volume of NaHSO4 used is given as 25.0 mL. We can calculate the concentration of NaHSO4 using the formula:

Concentration of NaHSO4 (mol/L) = Moles of NaHSO4 / Volume of NaHSO4 (L)
= 0.00510 mol / (25.0 mL x (1 L/1000 mL))
= 0.204 mol/L

Therefore, the concentration of the NaHSO4(aq) is 0.204 mol/L.

Answer 4

To find the concentration of NaHSO4(aq), we can use the balanced chemical equation for the reaction between NaHSO4 and NaOH:

NaHSO4(aq) + NaOH(aq) --> Na2SO4(aq) + H2O

From the balanced equation, we can see that the ratio of NaHSO4 to NaOH is 1:1. This means that for every mole of NaHSO4, we need 1 mole of NaOH.

In the given question, we know that 10.2 mL of 0.500 mol/L NaOH(aq) was added to reach the endpoint. To find the moles of NaOH added, we can use the following equation:

moles = volume (L) x concentration (mol/L)

Substituting the values, we have:

moles of NaOH = 0.0102 L x 0.500 mol/L
= 0.0051 mol

Since the ratio of NaHSO4 to NaOH is 1:1, the moles of NaHSO4 present in the solution is also 0.0051 mol.

Now we need to find the concentration of NaHSO4(aq) in the solution. The concentration is defined as the number of moles per liter of solution. Since we have 25.0 mL of solution, we need to convert it to liters:

volume (L) = 25.0 mL / 1000
= 0.0250 L

Concentration (mol/L) of NaHSO4(aq) = moles / volume
= 0.0051 mol / 0.0250 L
= 0.204 mol/L

Therefore, the concentration of NaHSO4(aq) is 0.204 mol/L.