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

Oserving the properties of water. Place a drop of water on a smooth plastic sheet or on the bench. Look at it closely from the side.

Free essay example:

CR yr12        Biology        01/11/2010

SOME OBSERAVATION ON WATER

Experiment # 1: Place a drop of water on a smooth plastic sheet or on the bench. Look at it closely from the side. Draw the outline of the drop. How are the molecules held in their place?image00.png

  • The drop of water and the drop of detergent have a different thickness, because the molecules are held differently. The drop of water, in fact, has a higher thickness. The molecules are closed to each other and it's possible to notice the surface that behaves as an elastic membrane that surrounds and compresses the underlying liquid. There is a force of cohesion that determines the surface tension.                                

Experiment #2: Fill a clean 250 ml. beaker with water to about 1 cm. below the top. Carefully float  a small filter paper on the surface. Carefully drop a needle, exactly horizontal, on the paper. Wait until the paper becomes soaked and sinks. Observe the needle carefully. After you have observed it, add one drop of detergent with a glass or plastic rod.

  • the piece of paper floats on the water and then it sinks because it get too wet. the needle continues to float, although its specific gravity is higher than the water's one, maybe because the water surface forms a kind of membrane ( see: ex.#1), impenetrable by small objects (as the needle). Adding the detergent, the needle has sunk because the detergent breaks the bonds between water molecules that allowed to the needle to float. Very carefully, it's possible to notice that the water surface gets curved under him ( as when we break a membrane, exactly).image01.png

Experiment #3: Place a 250 ml. baker on a quite bench. Carefully, fill it into the brim (the top). Now carefully add water drop by drop until it begins to overflow. Now carefully add small amounts of Ammonium Chloride to the beaker using a spatula. How much can you add before the water overflows?

  • Although we put lots of ammonium chloride, the water didn't overflow. That's really strange, because another little drop of water would make it overflow! This happened because the ions of the ammonium chloride attract the water molecules, so they are closer together and therefore they take less space.

Experiment #4: Fill a baker to halfway. Scatter chalk dust over the surface. Now add one drop of detergent with a glass or plastic rod. Observe and explain.image02.png

  • The Lycopodium moved immediately when it enters in contact with the drop of detergent.  That's maybe because the detergent is totally not attracted by the lycopodium. [ ... ]

Experiment #5: Fill a clean 250 ml. beaker to about 1 cm. below the top. Place two glass rods in the beaker, side by side. Where is the water between them? If it's not easy to see, add some drops of a dye to make water more visible.image03.png

  • Water is just attached to the glass, and it is possible to find it also outside the beaker, in the back of the two glass rods (as shown in the figure). That's probably because if the space is smaller, the pull is stronger. Glass molecules are bigger than water molecules, so they use to attract them.

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

(?)

Here's what a star student thought of this essay

4 star(s)

Response to the question

Overall a cleverly carried out and explained experiment. It provokes thought from the reader and the candidate shows well thought out reasons as to why each experiment proceeds as it does. To improve their mark, the candidate should include a ...

Read full review

Response to the question

Overall a cleverly carried out and explained experiment. It provokes thought from the reader and the candidate shows well thought out reasons as to why each experiment proceeds as it does. To improve their mark, the candidate should include a conclusion on the properties of water tying all the different experiments together.

Level of analysis

The experiments are very cleverly done and an attempt is made at an explanation. However, the first explanation of cohesion is not very well done. Bonds between water are explained at a base level. The diagrams help in the explanation and the methods of each experiment are stated clearly. One or two hypothesis seem to be guesses but most of the candidates work is correct even though it lacks deeper scientific detail.

Quality of writing

Minor grammatical errors present in places, also some careless spelling mistakes present. Other than this most of the document is fine in terms of punctuation, grammar, spelling and layout


Did you find this review helpful? Join our team of reviewers and help other students learn

Reviewed by skatealexia 07/07/2012

Read less
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

Related GCSE Science Skills and Knowledge Essays

See our best essays

Related GCSE Aqueous Chemistry essays

  1. The aim of this experiment is to answer the following question: What is the ...

    Once again the positive charge is delocalised throughout the double bond and can by draw in a number of resonance hybrids. The lone pair of electrons on the water molecule then attacks the positive charge on this carbon Now a proton on the bottom oxygen is transferred to another lone

  2. How much Iron (II) in 100 grams of Spinach Oleracea?

    Using a 50 cm3 measuring cylinder measure out approximately 50 cm3 of distilled water (l) and pour it into the beaker, using a glass rod stir the water and solid together until the entire solid has dissolved. c. Transfer the contents of the beaker through a small funnel into a 250cm3 volumetric flask.

  1. The action of amylase and pectinase in varying amounts when clarifying cloudy apple juice.

    to find out what is the optimum temperature for amylase and pectinase to work and for how long they need to be left at that temperature. I will also try 3 different types of apple juice. In this way I can see which type of apple juice clarifies the best.

  2. Investigating the effects of changing the concentration of different solutions on the refractive index ...

    Day 3 After that, I started using the binocular microscope shown in Photo 4. From those textbooks, I got some sort of idea that to find the refractive index of a solution, I will have to follow a few steps.

  1. Free essay

    An experiment to prepare ethene gas from ethanol and examine its properties

    tubes filled with ethene and apply a light to the mouth of the test tube using a lighted splint. Allow the gas to burn and when it has stopped burning add a small amount of lime water to the test tube, stopper it and shake the tube a few times.

  2. construction science and materials

    The additives and the remaining binder are then added to the paint mixture. Next, the thinner is added finally, the paint is put in to tins. STEEL: Steel is an alloy of iron and carbon containing less than 2% carbon.

  1. Factors affecting cell membrane permeability.

    Maintaining the temperaure for tubes 6, 7 and 8 was not a source of error, because the tripod was moved from the fire and then moved back to maintain the temperature for two minutes. Conclusion and evaluation: The experiment showed that the first hypothesis is not supportive, because rinsing or

  2. Antacid Experiment.

    + Hydrochloric acid (aq) --> Sodium chloride (aq) + Carbon Dioxide (g) + Water (l) NaHCO3 (sol)+ 1HCl (aq )--> 1Na Cl (aq)+ H2O (aq) + CO2 (gas) Initial Calculations. For all these calculations I shall be using 1 Molar of hydrochloric acid. Moles of antacid acid = mass / relative formula mass Number of moles of acid

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