I just want to make sure I understand and got these right:

What is the conjugate base of hydrogen phosphate?

What is the concentration of 1.55 M NaOH is required to titrate 24 mL of a 0.75 M HI solution?

When a small amount of HCl is added to a solution containing equimolar amounts of NaF and HF, which of the following statements is true?
A. [NaF] < [HF] because the HCl reacts with the conjugate base.
B. [NaF] > [HF] because the HCl reacts with the conjugate base.
C. [NaF] < [HF] because the HCl reacts with the conjugate acid.
D. [NaF] > [HF] because the HCl reacts with the conjugate acid.

HPO4 2- + H2O => H3O+ + PO4 3-
HPO42- is the acid, water the Base and H3O+ the corresponding acid and phosphate the coresponding base.

QuoteWhat is the concentration of 1.55 M NaOH is required to titrate 24 mL of a 0.75 M HI solution?

The sentence make no sense. It must be which  volume of 1.55 M NaOH is required to titrate 24 mL of a 0.75 M HI solution?
24ml * 0,75 mmol/l = 18 mmol

18 mmol/ 1,55 mmol/ml = 11,61 ml

If you add HCl to a mixture of NaF/ HF then the H of the HCl will exchange the Na and more HF is produced.

[NaF] < [HF] because the HCl reacts with the conjugate base, which is the Flouride.

Quote from: ann on March 21, 2023, 02:16:50 PM


What is the conjugate base of hydrogen phosphate?

Remove H ⁺ from HPO4^2- to get the conjugate base.

Quote from: ann on March 21, 2023, 02:16:50 PM


What is the concentration of 1.55 M NaOH is required to titrate 24 mL of a 0.75 M HI solution?

First write the balanced equation and check the molar ratio in for NaOH and HI .
Now moles = M*V(L)
get the moles of HI and convert them to moles of NaOH
Use M= moles / V(L to know the volume.

Quote from: ann on March 21, 2023, 02:16:50 PM

When a small amount of HCl is added to a solution containing equimolar amounts of NaF and HF, which of the following statements is true?
A. [NaF] < [HF] because the HCl reacts with the conjugate base.
B. [NaF] > [HF] because the HCl reacts with the conjugate base.
C. [NaF] < [HF] because the HCl reacts with the conjugate acid.
D. [NaF] > [HF] because the HCl reacts with the conjugate acid.

F- is the base from HF
When HCl is added it increase the concentration of HF and decreases the concentration of F-.