Question

Milk of magnesia is often taken to reduce the discomfort associated with acid stomach or heartburn. The recommended dose is 1 teaspoon, which contains 4.00×102mg of Mg(OH)2. Part A What volume of an HCl solution with a pH of 1.3 can be neutralized by one dose of milk of magnesia?

Answer 1

Answer:

Volume of HCl = 0.0688 L

Explanation:

pH is defined as the negative logarithm of the concentration of hydrogen ions.

Thus,  

pH = - log [H⁺]

So, pH = 1.3

Thus, 1.3 = - log [H⁺]

[H⁺] = 0.05012 M

Since, HCl is a strong acid, the concentration of HCl = 0.05012 M

Also,

Moles of $Mg(OH)_2$:-

Mass = $4.00\times 10^2\ mg$

Also, 1 mg = 0.001 g

So =, Mass = $0.4\ g$

Molar mass of $Mg(OH)_2$ = 58.32 g/mol

The formula for the calculation of moles is shown below:

$moles = \frac{Mass\ taken}{Molar\ mass}$

Thus,

$Moles= \frac{0.4\ g}{58.32\ g/mol}$

$Moles_{Mg(OH)_2}= 0.0069\ mol$

According to the reaction:-

$Mg(OH)_2 + 2 HCl\rightarrow MgCl_2 + 2 H_2O$

1 mole of $Mg(OH)_2$ neutralizes 2 moles of HCl

Considering:

$Molarity=\frac{Moles\ of\ solute}{Volume\ of\ the\ solution}$

So,

$Moles =Molarity \times {Volume\ of\ the\ solution}$

Thus,

$Moles_{Mg(OH)_2}=2\times Molarity_{HCl}\times Volume_{HCl}$

Appyling values as:-

$0.0069=2\times 0.05012\times Volume_{HCl}$

Volume of HCl = 0.0688 L