Question

A student uses 0.10 M HCl to simulate the acid concentration in the stomach. What volume( in ml) of “stomach acid” reacts with a tablet that contains 0.10 g of magnesium hydroxide?

Answer 1

Given, concentration of HCl = 0.10 M

Mass of Mg(OH)₂ = 0.10 g

Molar mass of Mg(OH)₂ = 58.3197 g/mol

Moles  = mass /molar mass

Mole of Mg(OH)₂ = 0.10 g/ 58.3197 g/mol

Mole of Mg(OH)₂ = 1.71

Mg(OH)₂(s) + 2HCl(aq) → MgCl₂(aq) + 2H₂O(l)

According to the balanced equation 1 moles of Mg(OH)₂ reacts with 2 moles of HCl.

Therefore, 1.71  moles of Mg(OH)₂ reacts with (2 x 1.71) or 3.42 moles of HCl

Molarity = moles / volume in L

Volume of HCl = 3.42 moles of HCl / 0.10 M HCl

Volume of HCl = 34.2 L or 34200 ml

34200 ml of “stomach acid” reacts with a tablet that contains 0.10 g of magnesium hydroxide.