Question

Question #9fe3d

Answer 1

`0.2M`

Explanation:

There are two methods you can use to solve this problem.

First method:

Since the two solutions neutralize each other then we can use the equation

`C_1 V_1 = C_2 V_2`

Where `C_1` is the concentration of `KOH`, `V_1` is the volume of `KOH` and `V_2` is the volume of `HNO_3`.

Substitute the values into the equation.

`(0.15M)(10mL) = (C_2)(7.5mL)`
`1.5 = (C_2)(7.5)`
`C_2 = 0.2M`

Second Method:

This is essentially a longer version of method 1 but I find that it works well in actually fostering understanding, rather than just taking the shortcut.

To do this, you first need to find the no. of moles in the solution for which you know both concentration and volume. In this case, `KOH`.

Using `M = (n\ mol)/V`, `0.15M = (n\ mol)/(0.01L)`

`= 0.0015 mol` The number of moles in the base solution and acid solution are equal.

Using the same formula, `M = (0.0015\ mol)/(0.0075 L)`

`M = 0.2`