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

Determining the water of crystalisation

Extracts from this document...

Introduction

DETERMINING THE WATER OF CRYSTALISATION INTRODUCTION Water of crystallization is water, which is present in the compound but is not covalently bonded to the host molecule. Hydrated salt (also known as hydrate) is an ionic compound, which is associated with water of crystallization. To show how much the salt is hydrated the notation can be written: salt * nH2O; where n represents the number of water molecules per one molecule of salt. The aim of this investigation is to find the number of moles of water present in hydrated salt: copper sulphate (CuSO4). Equipment, materials and reagents. REAGENTS EQUIPMENT Copper sulphate - CuSO4 * crucible with lid * weight balance (accuracy ? 0.01g) * Bunsen burner * tangent * crucible tongs * clock (accuracy ? 1s) Variables. DEPENDENT VARIABLES CONTROLLED VARIABLES INDEPENDENT VARIABLES FIXED VARIABLES * mass of salt * type of salt * humidity * temperature * pressure Environmental care and safety. The product is obtained in a small amount and does not make up a potential danger for the environment, thus it can be disposed down the sink. Hydrated copper sulphate is poisonous and it can be absorbed into the body by inhalation or by ingestion. Moreover it can irritate the eyes and skin so apron, glasses and protective gloves are required. It is also advised to make the investigation in well-ventilated room to avoid the inhalation. ...read more.

Middle

Calculation of initial mass of salt (hydrated) Tab 3. Recordings needed to calculate the initial mass of salt. object weighted Mass [? 0.01g] empty crucible with lid 37.70 crucible with lid and hydrated salt 44.92 Mass of salt = mass of crucible with lid and hydrated salt - mass of empty crucible with lid Providing the numbers to the equation above I calculated the mass of salt. Initial mass of CuSO4 = 44.92g - 37.70 g = 07.22g [? 0.02g] Uncertainty: % uncertainty in mass of hydrated CuSO4 = (0.02/7.22)*100% = 0.28% 2. Calculation of mass of anhydrate salt (CuSO4) Tab 4. Recordings needed for calculating the mass of dehydrated salt. object weighted mass [? 0.01g] crucible with lid and salt (after last heating) 42.30 empty crucible 37.70 Mass of anhydrate salt = mass of crucible with lid and salt (anhydrate) - mass of empty crucible with lid Mass of anhydrate CuSO4 = 42.30g - 37.70g = 04.60g [?0.02g] Uncertainty: % uncertainty in mass of anhydrate CuSO4 = (0.02/4.60)*100% = 0.43% 3. Calculation of mass of water evaporated Tab 5. Recordings needed to calculate the mass of water evaporated substance mass [? 0.01g] hydrated salt 7.22 dehydrated salt 4.60 Mass of water evaporated = mass of hydrated salt - mass of dehydrated salt Mass of water evaporated = 7.22g - 4.60g = 2.62g [? ...read more.

Conclusion

Improving the investigation. As I mentioned before, there are some things, which can be improved while doing this type of experiment. The most important thing it to know the source of salt and its purity. Apart from that there is another method for determining the water of crystallisation present in salts called Thermal Gravimetric Analysis (TGA), which seems to be more precise and appropriate for all salts. Thermogravimetric Analysis or TGA is a type of testing that is performed on samples to determine changes in weight in relation to change in temperature. Such analysis relies on a high degree of precision in three measurements: weight, temperature, and temperature change. TGA is commonly employed in research and testing to determine characteristics of materials such as polymers, to determine degradation temperatures, absorbed moisture content of materials, the level of inorganic and organic components in materials, decomposition points of explosives, and solvent residues. It is also often used to estimate the corrosion kinetics in high temperature oxidation The analyzer usually consists of a high-precision balance with a pan loaded with the sample. The sample is placed in a small electrically heated oven with a thermocouple to accurately measure the temperature. The atmosphere may be purged with an inert gas to prevent oxidation or other undesired reactions. A computer is used to control the instrument. Analysis is carried out by raising the temperature gradually and plotting weight against temperature. After the data is obtained, curve smoothing and other operations may be done such as to find the exact points of inflection. [1]. ...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 Classifying Materials 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 Classifying Materials essays

  1. Determine the formula of the hydrate in hydrated copper (II) sulfate empirically, i.e. to ...

    = 1.267g/[63.55 g.mol-1 + 32.06 g.mol-1 + 4(16.00) g.mol-1] = 1.267/159.61 mol n(CuSO4) ? 0.00794 mol ? 2.5x10-5 mol n(H2O) = 0.767g/[2(1.01) g.mol-1 + 16.00 g.mol-1] = 0.767/18.02 mol n(H2O) ? 0.0426 mol ? 4.4x10-4 mol The ratio can now be easily determined: CuSO4 : H2O n(CuSO4)/ n(CuSO4) : n(H2O)/n(CuSO4) (1.267/159.61)/( 1.267/159.61) mol : (0.767/18.02)/(1.267/159.61)

  2. Our experiment consisted of two samples of water containing unknown substances, and our objective ...

    Make sure the reading displays '0.00g'. If it doesn't, calibrate it by pressing a button which says 'On/Zero'. 8. After the evaporating basin has cooled, put it on the weighing scales and record the reading in your book. 9. Measure out 20cm3 of the sample using the measuring cylinders and maybe a pipette if you need to.

  1. should salt be banned?

    Meanwhile, the producers of an organic Welsh sea salt that has been praised by chefs world-wide said their product could naturally help cut salt intake because of its strong flavour. The makers of Anglesey's Halen M�n - recently ranked one of the "world's top five gastronomic products" - believe this could, in itself, leave diners using less of the product.

  2. Determination of the formula of hydrated iron sulphate

    5Fe2+ : MnO4- So moles of Fe2+ in 25cm3 of solution = 5 x 0.0002225 = 0.00113 So moles of Fe2+ in 25cm3 of solution = 0.00113 This is the number of moles of Fe2+ in 25cm3. I used 250 cm3 so the number of moles in 25cm3 needs to

  1. formula for copper sulphate

    ; the burette is used to measure the volume of solution added and it has a degree of 0.05cm3 and the flask is used to make up an accurate volume of solution usually in a 250cm3. However, with the burette, the reading should be always recorded at two decimal places

  2. Determination of the formula of Hydrated Iron (II) Sulphate Crystals

    * Moles of Fe2+ = 0.00019*5 o = 0.00095mol I titrated the FeSO4 of 25cm3, however because it was diluted up to 250cm3 I will have to multiply the moles by 10. * Moles of FeSO4 = moles of Fe2*10 o = 0.00095*10 = 0.0095mol Firstly, I will find the

  1. Investigation to Identify the Formula of Hydrated Copper Sulphate and in doing so Find ...

    0.002 g Initial observations of hydrated copper (II) sulfate: Blue crystalline solid A Table to Show Results of Gentle Heating of CuSO4 � xH2O ITERATION(every 3 mins) INITIALMASS (g) OBSERVATIONS DURING HEATING FINAL MASS (g) OBSERVATIONS POST-HEATING |ERROR| (g) 0 10.058 *Before Heating 10.058 *Before Heating ? 0.002 1st 10.058 Gradual whitening of blue crystals; visible reduction of

  2. Separating Salt & Fat from Crisps

    Observations: Whilst evaporating, the chips+ water mixture started to bubble when the temperature was raised. This means that the molecules started moving faster and started moving in random directions and colliding with each other. On the beaker condensation also formed and vapor was visible coming from the beaker.

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