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

Volume of HCl = 0.0688 L

Step-by-step 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* 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 = (Mass\ taken)/(Molar\ mass)`

Thus,

`Moles= (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=(Moles\ of\ solute)/(Volume\ of\ the\ solution)`

So,

`Moles =Molarity * {Volume\ of\ the\ solution}`

Thus,

`Moles_(Mg(OH)_2)=2* Molarity_(HCl)* Volume_(HCl)`

Appyling values as:-

`0.0069=2* 0.05012* Volume_(HCl)`

Volume of HCl = 0.0688 L