- Level: International Baccalaureate
- Subject: Chemistry
- Word count: 2143
PURPOSE To determine the amount of water of crystallization in one mole of a hydrated salt and its formula
Extracts from this document...
Introduction
IBDP-1 IBDP (2012-2014) INTERNAL ASSESSMENT COVER PAGE CHEMISTRY NAME OF STUDENT NAME OF TEACHER TITLE OF INVESTIGATION LEVEL - HL SL DATE - TOPIC - TIME (IN HOURS) - USE OF ICT (IF ANY) ? DATA LOGGING GRAPH PLOTTING SOFTWARE SPREADSHEET DATABASE COMPUTER MODEL / SIMULATION CRITERIA ASSESSED DESIGN (D) DATA COLLECTION AND PROCESSING (DCP) CONCLUSION AND EVALUATION (CE) PURPOSE To determine the amount of water of crystallization in one mole of a hydrated salt and its formula. HYPOTHESIS Hydrates are inorganic ionic salts that contain a specific number of water molecules loosely attached as a part of their structure. The water is chemically combined with the salt in a definite ratio. In this experiment, the percentage composition of water can be calculated based on the masses of the anhydrous and hydrated salt. The chemical formula of this hydrate in general is CuSO4.XH2O. Thus the achieved result from this experiment should probably be x=5. Therefore copper sulphate should have a formula of CuSO4.5H2O. When it is heated gently, the water is released as vapours and we can describe this reversible reaction as: CuSO4.5H2O CuSO4 ...read more.
Middle
Sulfate Mass of hydrated salt 2.0 + 0.1g 3.0 + 0.1g 4.0 + 0.1g Mass of crucible 46.0 + 0.1g 46.0 + 0.1g 46.0 + 0.1g Mass of crucible + hydrated salt 48.0 + 0.1g 49.0 + 0.1g 50.0 + 0.1g Mass of crucible and contents after heating #1 47.5 + 0.1g 48..3 + 0.1g 48 + 0.1g Mass of crucible and contents after heating #2 47.3 + 0.1g 47.9 + 0.1g 47.2 + 0.1g Mass of crucible and contents after heating #3 47.3 + 0.1g 47.9 + 0.1g 47.4 + 0.1g Mass of anhydrous salt 1.28 + 0.1g 1.9+ 0.1g 2.6 + 0.1g Percentage of water in hydrated salt 36.0 + 0.1% 36.1 + 0.1% 35.9 + 0.1% Moles water in hydrated salt 0.04 0.06 0.08 Formula for anhydrous salt CuSO4 Moles of anhydrous salt 0.008 0.011 0.016 Formula for hydrated salt CuSO4.5H2O CALCULATIONS: 1. The value of x in CuSO4.xH2O Sample 1: Mass of water = mass of hydrated salt ? mass of anhydrous salt = 2 ? 1.28 = 0.72 g Moles of water = mass / Mr = 0.72 / 18 =0.04 Moles of CuSO4 = mass / Mr = 1.28 / 159.62 = 0.008 Moles of hydration = moles (water) ...read more.
Conclusion
Sometimes the last water is a bit hard to drive off. Crushing the crystals will give you a lot more surface area. Weigh the powder, not the crystals. In a hydrate the water molecules are a distinct part of the compound but are joined to the salt by connections that are weaker than the connections in the salt or the connections in the water molecules. We use a dot to connect the water units to the salt formula ( CuSO4.5H2O). Hence the name of the salt is copper sulphate pent hydrate. It?s used as an herbicide, fungicide and pesticide and mainly for chemistry education in schools. EVALUATION: The dish must be weighed before the compound absorbs any moisture from the air and so should have covered it with a filter paper. Also I did not weigh the mass of the crucible and its contents when it is hot as heat waves tend to spiral upwards, resulting in masses to be measured less than the actual value. All these factors do affect the results. Sometimes the last water is a bit hard to drive off. Crushing the crystals will give a lot more surface area. Hence, one should weigh the powder, not the crystals. ...read more.
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