Softening Hard Water With Sodium Carbonate

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Softening Hard Water With Sodium Carbonate

Prediction

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In a preliminary experiment, we discovered that adding 1g. Na2CO3 to

hard water softened it slightly. We tested both tap water and

distilled water with the sodium stearate and discovered that tap water

was far harder than distilled water, we then tested tap water that 1g

of Na2CO3 had been applied to. This solution was softer than the

original tap water. The exact results were;

Type of water

Soap solution required

1st attempt

2nd attempt

Average

Distilled

0.5

0.5

0.5

Tap

4.5

5.0

4.75

Tap with 1g. Na2CO3

3.5

3.0

3.25

This tells us that Na2CO3 softens hard water. However 1g Na2CO3 did

not render it as soft as distilled water. Now our aim is to determine

whether increasing the quantity of Na2CO3 added to the hard water

softens it more effectively. We are measuring the hardness of the

water by the volume of soap solution required to produce a lather.

Thus, the less soap solution required to form a lather, the softer the

water, and the more successful the Na2CO3.

We know that 1g Na2CO3 did not fully soften the water. My prediction

is that as the quantity of Na2CO3 is increased, the water will become

softer. Thus requiring less soap to form a lather. Additionally I

predict that after a certain point the Na2CO3 will become less

effective at softening the water until finally it will not effect the

softness of the water if more Na2CO3 were to be added.

Water is made hard by dissolved calcium ions, Ca2+, when placed into a

solution Na2CO3 splits up into Na+ ions and CO32- ions, the CO32- ions

combine with the dissolved calcium ions to create calcium carbonate,

this is a solid precipitate that doesn't alter the softness of the

water. The sodium ions stay dissolved in the water, but they don't

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