The Effect of Sodium Carbonate on Hard Water

3102 Words7 Pages

The Effect of Sodium Carbonate on Hard Water

Aim

===

In this experiment, we aim to investigate the effect of sodium

carbonate on hard water.

Method

======

Firstly, 25.00cm3 of a sample of water was pipetted into a clean

conical flask. The pipette was used because this measures and delivers

a very accurate amount of liquid (to the nearest hundredth of a cm3,

or 0.01cm3), but care had to taken to make sure it was not held by the

bulge, as this could have made the amount inaccurate (as body

temperature heats the apparatus up and makes it expand). Also, the

pipette is used to avoid spillage, as the thin tube can put the water

straight into the appropriate container. Furthermore, a pipette filler

was used for safety purposes, because blowing or sucking could get

unwanted and potentially dangerous substances into the mouth. 0.500g

of sodium carbonate (a white powder) was added to the water, having

been carefully weighed on an electronic balance - this was very exact

and had a cover to maximise accuracy (it protected the balance from

being affected by wind or other particles). The balance measured the

mass of the powder to the nearest thousandth of a gram (i.e. 0.001g).

Then a burette on a stand was obtained, a considerable amount of soap

solution funnelled into it through the top (so the level reached near

the top) and 1cm3 of the solution added to the water. The burette

(glass tube with measurements marked on the side and a stopcock at the

bottom) was used because it very accurately lets out 1cm3 every time.

The conical flask was then corked (so no substances were able to

escape through the top) and shaken for ten seconds (this timed by a

stop-watch). It was observed whether a permanent lather (one that

lasted for more than ten seconds - again a stop-watch was used) was

created. If so, the result of 1cm3 being added was recorded. If not,

then the process of adding a cm3 of soap solution and shaking the

Open Document