Question

If 25 mL of KOH were needed to neutralize 15 mL of 3.5 M HBr, calculate the molarity of the base

Answer 1

2.1 M KOH is required.

Step-by-step explanation:

It is an example of acid-base neutralization reaction.

KOH + HBr ----> KBr +
`H_(2)O`

Base Acid Salt

When two component react then the number of moles of both the component should be same, therefore the number of moles and acids and bases should be the same in the following .

Molarity=
`\frac{\textrm{No. of moles}}{\textrm{Volume of the particular solution}}`

No.of moles= Molarity × Volume of the Particular Solution

Therefore,

`M_(1) V_(1) = M_(2) V_(2)`------------------------------(1)

where

`M_(1)`= Molarity of Acid

`V_(1)`= Volume of Acid

`M_(2)`= Molarity of Base

`V_(2)`= Volume of Base

`M_(1)`=3.5 M

`V_(1)`=15 mL

`V_(2)`=25 mL

`M_(2)`=??(in M)

Plugging in Equation 1,

3.5 × 15 =
`M_(2)` × 25

`M_(2)`=
`(3.5 * 15)/(25)`

`M_(2)`=2.1 M