Given that the antacid milk of magnesia contains 400. mg of Mg (OH) 2 per teaspoon, calculate the number of milliliters of stomach acid that are neutralized by 1 tablespoon of milk of magnesia. (1 tablespoon 3 teaspoons.) Express the volume in millilite rs to two significant figures.

1.5 ml

Explanation:

Assuming that the stomach acid is HCl then:

Mg (OH) ₂ + 2HCl → MgCl₂ + H₂O

since

number of moles of Mg (OH) ₂ = mass / molecular weight of Mg (OH) ₂ = 3*400 mg / 58.3 gr/mol = 20.583 m mol

thus

number of moles of HCl required = number of moles of Mg (OH) ₂*2 = 41.166 m mol = 41.166 m moles

knowing that

density = mass / volume = (molecular weight * moles) / volume

volume = (molecular weight * moles) / density

thus for HCl

volume = (36.46 gr/mol * 41.166*10^-3 moles) / (1 gr/cm³) = 1.5 cm³ = 1.5 ml