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

Deriving a Solubility Curve

Extracts from this document...


Deriving a Solubility Curve- Practical Report Aim: - To observe the change in solubility of an ionic compound, potassium nitrate, as the temperature is increased. - To plot the solubility curve of an ionic compound, potassium nitrate, on the basis of experimental data. Apparatus: As per prac sheet Method: As per prac sheet Safety: See risk assessment sheet Results: Solubility Table Mass of solute (KNO3) Mass of solvent (H2O) Solubility (g of KNO3/100g of H2O) Temperature (� C) (at first sign of crystallisation) 6.5g 5ml 130g 81�C 6.5g 8ml 81.25g 54�C 6.5g 11ml 59.1g 47�C 6.5g 14ml 46.43g 27�C 6.5g 17ml 38.24g 20�C 6.5g 20ml 32.50g 20�C 6.5g 23ml 28.26g 13�C Find solubility curve attached to the end of the report. Calculations: To find solubility, the mass of solute (KNO3) was divided by the mass of solvent (H2O), and then multiplied by 100. 6.5 � 100 = 130 5 6.5 � 100 = 59.1 11 6.5 � 100 = 38.24 17 6.5 � 100 = 28.26 23 Questions: Refer to prac sheet for questions. 1) From the graph of the solubility curve, it can be determined that: a) ...read more.


is the solvent. Polar molecules and Ionic Compounds A polar molecule has both positive and negatively charged ends. Water is a polar molecule because it has a difference in electronegativity between atoms, and has an uneven distribution of charges (molecule is asymmetrical): Due to the difference in electronegativity between atoms, the oxygen atoms are slightly negatively charged because they have greater electronegativity (ability to attract negatively charged electrons), and the hydrogen atoms are slightly positive. Potassium nitrate (KNO3) is an ionic compound because the potassium (K ) is positively charged, and the nitrate is negatively charged (NO3 ). The electrostatic forces of attraction between the oppositely charged ions hold the ions together (ionic lattice), forming an ionic compound. Dissociation Potassium nitrate is able to dissolve in water because H2O is polar and KNO3 is an ionic compound. When potassium nitrate is placed in water, the slightly positive charge of the H2O molecule is attracted to the negative ion, NO3, and the negative charge of the H2O molecule is attracted to the positive ion, K. As water molecules are in a continuous state of random movement, they pull the potassium cations and nitrate anions of the outer part of the crystal out of the lattice structure and into the surrounding solution. ...read more.


By changing the ratio, we are able to observe the relationship of temperature to solubility. It was heated and once again, cooled (with the aid of cold water to speed up the process) until the first sign of crystallisation. These steps were repeated several times, so that a sufficient amount of recordings could be used to draw an accurate solubility curve. Errors: The systematic error in this experiment is the possibility of a calibration error on the balance. Random errors in the experiment include: measuring the incorrect amount of water added to the solution, incorrectly reading the thermometer, not noting the temperature at the exact moment crystallisation starts to occur, heating the water to a point where some begins to evaporate (changing the ratio of solute to solvent) and a possible mistake in graphing the solubility curve. Improvements include: more time needed to gather more data (possibly do the experiment again and find an average to even out extreme results), and a stopper on the test tube would stop the evaporation of water. Conclusion: The solubility curve derived from the experiment visually shows that as the temperature of the solvent (H2O) increases, the solubility of the solute (KNO3) increases as well (more potassium nitrate can be dissolved in 100grams of H2O). ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Inorganic 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 AS and A Level Inorganic Chemistry essays

  1. Peer reviewed

    Deducing the quantity of acid in a solution

    5 star(s)

    So then, what can we do to judge it properly or at least to try to find the closest endpoint to the actual one? Apart from reading the mark using with paper, we also kept a sample of the second titre after the rough one and then compared the colours when doing the following ones.

  2. effects Concentration and Temperature on the Rate of Reaction

    The computer can provide better accuracy than I can as far as drawing the axes and plotting the points is concerned. However, I believe that I can provide more accuracy when drawing the line or curve of best fit.My line of best fit suggests that the reaction, with respect to potassium bromate(V), is first order.

  1. an experiement to test for anions and cations

    No precipitate was formed, so the test tube was placed back into the Bunsen flame, with a piece of moist litmus paper placed over the top of the tube (ensuring that it didn't touch) 5. The paper turned from red to blue, indicating that substance I was ammonium.

  2. Scientific Practical Techniques

    Result of the experiment presented in table Sample 1 Square Number of cells 1 6 2 4 3 10 4 10 5 19 Total 49 cells Sample 2 Square Number of cells 1 19 2 12 3 14 4 15 5 15 Total 75 cell Sample 3 Square Number

  1. The Effects of Strong and Weak Acids on the Order of a Reaction.

    8) Do the same experiment for the other acid - ensuring that you repeat it until you have 3 values for each. Results Table for Order HCl - Volume (cm�) Time (s) 1 2 3 Average Vf-Vt 0 0 0 0 0 93 5 41 35 40 38 55 10 59

  2. Determination of the solubility of calcium hydroxide

    At the same time making sure the bottom of the meniscus is on the 250cm-3 line. I will then add a rubber bung into the end of the volumetric flask, and shake to mix the hydrochloric acid with the water.

  1. Chemistry - Data Analysis

    There was strictly no walking around with hot water. iv) No equipment, including bags and books were left on the tables. (apart from experiment equipment)- shown above Results: TIME TEMPERATURE Paper Cup Plastic Cup Polystyrene Cup averages 1 2 3 1 2 3 1 2 3 TIME paper plastic

  2. Aim To study the effect of concentration of iodide ion ...

    A trial run was performed to identify possible weaknesses and shortcomings, and thus in the process, design actual experimental procedures. Control of Variables Concentration of iodide solution The concentration of iodide solution is equivalent to the concentration of potassium iodide KI solution since potassium ions are spectator ions.

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