# Question #69999

##### 1 Answer

The calculation makes several assumptions, but I think you need 0.75 mL of 25 % ammonia solution.

**Step 1**

HPMCP is hydroxypropylmethylcellulose phthalate.

The repeating unit in HPMCP is

This gives a formula of C₃₅H₄₁O₁₈ and a molar mass of 749.7 g.

HPMCP is a diprotic acid. Let's write it as H₂A.

Then

H₂A + 2NH₃ → 2NH₄⁺ + 2A⁻

The density of 25 % aqueous NH₃ is 0.911 g/cm³.

**Step 2**

HPMCAS is hydroxypropylmethylcellulose acetate succinate. The repeating unit in HPMCAS is

This gives a formula of C₃₂H₅₀O₂₀ and a molar mass of 754.7 g.

HPMCAS is also a diprotic acid. Let's write it as H₂A.

Then

H₂A + 2NH₃ → 2NH₄⁺ + 2A⁻

**Step 3**

Total volume = 0.70 mL + 0.050 mL = 0.75 mL