• 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...

Introduction

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.

Middle

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.

Conclusion

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

or


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)

    If the equipment is not well rinsed, the colour of the solution may change earlier or to a different colour, so it would be very inaccurate. Therefore, we rinse everything properly, three times each apparatus with their respective solutions. This will make the titration and therefore, the results, more reliable and accurate.

  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

    Testing for cations (Substance J) 1. A small spatula of substance I was added to a test tube, along with distilled water filling half of the test tube.

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

    Conclusion and evaluation Based on the experimental findings, it can thus be concluded that it is very likely that the concentration factor is affecting the rate of reaction of the iodide oxidation linearly. Based on the graph, as the concentration of the iodide solution increases, the rate of reaction of iodide oxidation increases too.

  1. Chemistry - Data Analysis

    This would affect the shape of the graph and hence the reliability of the gradients. Further evidence of the reliability is confirmed when the graph of all three experiments is analysed. This graph shows that the paper cup lost heat at the fastest rate followed by the plastic and polystyrene cups.

  2. Scientific Practical Techniques

    reading to settle > Press the CAL key to enter the calibration mode. The display flashes wait until the screen goes from OFF to CAL > 7 will appear on the screen and CAL will flash on the bottom corner the meter is now calibrating pH 7 > One I

  1. Determination of the solubility of calcium hydroxide

    I then empty the pipette into the volumetric flask, and touch the end of the pipette onto the side of the volumetric flask, to empty that final trace of the acid. 5. I will then fill the volumetric flask with distilled water up to the 250cm-3 mark.

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

    This shows that the time taken for the concentration of the reactants to be halved isn't constant. It is also important to note that Second order graphs tend to be deeper than first order graphs, however half-life comparisons must be done in order to gain an accurate reading of the two.

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