Question

Integrated Problems #13 Milk of magnesia (Mg(OH)2)is often taken to reduce the discomfort associated with acid stomach or heartburn. The recommended dose is 1 teaspoon (5 mL) which contains 4.00 X 10-mg of Mg(OH)2. 1) Magnesium hydroxide is a slightly soluble salt. Write a balanced equilibrium reaction for this process. 2) The Ksp for Magnesium hydroxide is 2.06 X 10-13, what is the pH of the recommended dose of milk of magnesia? 3) If we assume that stomach acid is HCl, write a balanced acid-base reaction for combination of milk of magnesia and stomach acid. Identify the acid, base, conjugate acid, and conjugate base. 4) What volume of stomach acid with a pH of 1.3 can be neutralized by one dose of milk of magnesia? 5) If the stomach contains 2.00 X 102 mL of pH 1.3 solution, will all the acid be neutralized? 6) If not what fraction is neutralized? 7) What is the new pH of the solution in the stomach following the single dose of milk of magnesia? 8) If the Mg(OH)2 forms a body centered lattice and has a density of 2.34 g/cm, what would be the length of the side (A)? 9 Write the Lewis structure of Mg(OH),. How does this structure differ from the hydronium (H30*) ion that it reacts with?

Answer 1

The calculations of these questions uploaded as images.
24 0 Mg (01), (5) = Mg (OH)2 (aq) = mg (22)+2017cm 00. -13 2-06 X 10 3 ② mg (0) Mg + 2010 S S 25 Let us suppose, Palivility of ing(OH)2 18 Smoll Uspa Solis listy product = [meg")[on? 00.2-06x103, S. (25) or 453 = 2.06x1013 07 5° = 2.06x0" = 0.5156173 07 S = (0.5154113)= 3.72 %100(09. The solubility of mg (OH) is 3.72x10 (11) So, [OH-] = 25 = (2x 3. 72 x105) — 7.441x185 DOH = -by Con3 = - bag (7441290°) – 4:128 pH = 14-poh = 114 - 4.128) = 9-871 07 3 - 206x10 -13 mol/L Therefore recommended dose of think of haguesia is 9.871

3 mg (OH)₂ + 2HCl = Mgel + 2H2O (Base) Acid) (Salt) (Wales) This is acid-base neutralisation reaction that occurs in Stomach when we eat the antacid milk of magnesia, 2+ Mg(OH), + 2HCl - Mg +20 +2H₂O (Base) (Aeid) Caungate (conjugate acid) base) Conjugate base of Hel laeid) is cl- Conjugate acid of my (on) (base) is right 6 1 dose = 5 me = 4x15² ing rg (0) n = 4x105.g of ing (8t) pH = 113 of, -ley ( 12877 = 1.3 or Hot] = 1063 88 [Hot] = 0.05011 (1) So, concentration of Hol = 0.5011 SMI

Let us suppose vme of Hell is required to neutralize I dose of Mg(OH)2 Here 2 mol of Hel is required to neutralize one mol of mg (OH)2. molt mass of rig (04) =(24+32+2)=56 - R 4x105 g of mg (OH)2 = 4x103 wel of 58 g (6472 - 0.0689x185 mol of reg(OH2 So, (2 x 0.0689x105) mol = 0.1379x105 mol of Hel is requered to heutralize I dose of trg (0H)2 Now, V me of 0.5011 (4) Itce (Vx0.2011 - 5x10 Xymoe of = (5x16 ) are hee Hence, (5x15xv) = 0.1370x105 on v= 0.1379x185 5x18- 4 = 0.00 27 me

So, 0.0027 mil Stomach acid with a PH. = 13 Can se neutralized by one dose of milk of magnesia,