## Thursday, 22 January 2015

### 7.3.1 - Laboratory Activity : Preparation of a standard solution

 Laboratory Activity 7.3.1: Preparation of a standard solution
Aim: To prepare 100cm3 of standard solution of sodium hydroxide, 2moldm-3
 Material: » Sodium hydroxide pellets » Distilled water in bottle Apparatus: » Volume flask (100cm3) » Electronic balance » Filter funnel » Beaker » Glass rod
Procedure:

1. The mass of sodium hydroxide pellets required is as follows:
 $\begin{array}{c}\text{=(number of mole x)}\mathrm{×}\text{(Relative formula mass)}\end{array}$ $\begin{array}{c}\text{=}\frac{\text{MV}}{100}\mathrm{×}\left(23+1+16\right)\end{array}$ $\begin{array}{c}\text{=}\frac{2x100}{1000}\mathrm{×}40\end{array}$ $\begin{array}{c}\text{=}8g\end{array}$
2. 8 g of sodium hydroxide in a beaker is weighed on an electronic balance.
3. Some distilled water is added to the alkali in the beaker and stirred to dissolve all the NaOH pellets.
4. The solution is poured into the volumetric flask through a clean filter funnel, along with the glass rod to prevent spillage.
5. Distilled water is added to the beaker and washed down into the volumetric flask.
6. Distilled water is added into the volumetric flask until it is slightly below the mark. Using a dropper, distilled water is added until it reaches the 100cm3 mark.
7. The flask is closed with its cover and shake gently to obtain a homogeneous solution.
Conclusion:
 ► The concentration of the sodium hydroxide solution is 2 moldm-3.