• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Which ions cause hardness in water?

Extracts from this document...

Introduction

Investigation Which ions cause hardness in water? Aim: I want to find out what ions cause hardness in water and the reasons as to why certain ions have an effect and others don't. Background information: Calcium hydrogen carbonate is the main cause of hard water. It forms when rain falls on rocks of limestone and chalk. These are made of calcium carbonate, which is not soluble in water. But rainwater contains carbon dioxide dissolved from the air, which makes it acidic. So it reacts with the rocks to form calcium hydrogen carbonate which is soluble and ends up in our taps. This reaction is: H20(l) + C02(g) + CaC03 - Ca(HCO3)2(aq) (Information taken from Complete Chemistry Book-Oxford University.) ...read more.

Middle

I also know that soap can be used to soften hard water, the chemical equation for this is: CaSO4+ 2C17H35COONa=Ca (C17H35COO)2+Na2SO4 (Calcium Sulphate+ Sodium Stearate= Calcium Stearate+ Sodium Sulphate) I think that the ions most likely to cause hardness are probably the 2+ ions because the cations seem to be the only thing that is having an affect on the situation. Method: The apparatus I will need to use is minimum, a test-tube, pipette and a measuring cylinder. I have to measure 6 ml of the chosen compound e.g. iron sulphate, to do this I will need to use a pipette to make sure that the measurements are very accurate. I need to measure 2 ml of Sodium Stearate (soap solution), which is to be added. ...read more.

Conclusion

Compounds with a cation charge of one were only present in soft water; anions were present in both hard and soft water, which by observation means that they have no affect. So by the evidence claimed only compounds with a cation charge of two produce scum. Evaluation: The results I obtained were all correct; there were no signs of anomalous results. As there were only two possible outcomes this made it easier to get the right result. I did each experiment twice to make sure that nothing could have gone wrong, to improve the experiment I could have used equipment that can measure the amount of scum or lather produced; also I could look into the effect of temporary hard water. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our GCSE Aqueous Chemistry section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related GCSE Aqueous Chemistry essays

  1. Investigate the hardness of water in 5 different water solutions

    the same amount of water for each test tube, which is 4ml and I will be using a measuring cylinder to measure this amount accurately. I will also use the same soap and the same amount of soap for each test tube.

  2. Analysing Soft Drink

    dm-3 Investigation 2: Determine the concentrations of blackcurrant juice in the diluted samples In order to find out the concentration of blackcurrant juice in the diluted samples, I'll use the following two methods * Colour matching * Colourimetry The technique /science The techniques for this experiment are Colour matching, Colourimetry and Calibration graph.

  1. the synthesis of azo dyes, aspirin and soap

    The hydrophilic end means having a strong affinity or attraction to water and the hydrophobic end means having a strong aversion for water. Soap is a surface active material as this chemical agent is capable of quick reaction activity. THE MAKING OF SOAP IN COLLEGE LABORATORY: PRACTICAL WRITE-UP Before the

  2. Science Coursework Investigation ions

    The volume of the gas should be recorded every minute. The reading from the measuring cylinder should be taken careful keeping in mind that parallax error should not occur. (Parallax error is when an object is viewed from the wrong angle e.g.

  1. Investigation into how the concentration of a metal ion affects the hardness of water.

    Shaking for as hard as possible is easier to maintain because it is a limit that cannot be changed easily. Shaking for 10 seconds can be timed with a stopwatch so it is relatively easy to control. It is important that this is maintained, because the length and strength of

  2. An investigation of the effect of concentration of a chosen ion on the ''Degree ...

    ions, I will also need to double the number of stearate (soap) ions. E.g. Ca & 2St 2Ca & 4St 4Ca & 8St Each time both amounts are doubled. If this was put into a graph of volume of soap used against concentration of calcium, it would be a straight line through the origin.

  1. In this experiment, we aim to investigate the effect of sodium carbonate on hard ...

    The graph (on pg. 3) takes this shape because the more sodium carbonate is added, the less soap solution it takes to give a permanent lather (as the water is made softer and softer). The graph levels off after a certain time, though.

  2. Which Ions Cause Hardness in Water?

    = Soap Calcium Stearate (Calcium Octadecanoate) = Scum As this is the reaction that softens hard water when it is caused by Calcium Sulphate, then this same formula should work for any other reaction between a hard water causing salt, and soap.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work