tongs, remove the crucible from the clay pipe triangle and allow it to cool be careful not to drop – the crucible it is hot! – Weigh the crucible again Repeat step 4, but this time heat for only 5 minutes Remove the crucible, allow it to cool and weigh it again If the mass has decreased again, repeat steps 8 and 9 until there is no further change in mass Report down your observations from Experiment 1 and explain what is happening. Write down your observations from Experiment 2 and answer the following questions: How effectively were you able to separate the two solids? What was the difference between the solids which allowed them to be separated in this way? Why would the techniques used in Week 1 not be effective for this separation? Write down your observations from Experiment 3 and explain what is happening Write down your observations from Experiment 4 and evaluate the effectiveness of this technique as a way of separating the two solids Write down your observations from Experiment 5 and explain what is happening Calculate the value of x in CuSO4.xH2O Week 3 Solubility and Solubility Curves – Chemical Principles The solubility of a substance is the quantity of that substances (in grams or moles) which can dissolve in a stated amount of solvent or solution (usually 100 ml or 1 dm3) at a given temperature. A solubility curve is a graph of solubility against temperature and hence shows the relationship between solubility and temperature. The solubility of most salts increases with increasing temperature, although there are a number of exceptions. In a small number of cases, the solubility of a substance may increase with increasing temperature up to a certain critical temperature, and then decrease again if the temperature is increased further; this happens if the most stable form of the solid changes - for example, sodium sulphate is most stable in hydrated form (Na2SO4.10H2O) at temperatures below 32.4 oC but in anhydrous form at temperatures above 32.4 oC; its solubility in water increases with increasing temperature up to a maximum at 32.4 oC but decreases with increasing temperature above 32.4 oC. The temperature of maximum (or minimum) solubility is called the transition It occurs at the same temperature for all solvents.
tongs, remove the crucible from the clay pipe triangle and allow it to cool – be careful not to drop the crucible – it is hot! Weigh the crucible again Repeat step 4, but this time heat for only 5 minutes Remove the crucible, allow it to cool and weigh it again If the mass has decreased again, repeat steps 8 and 9 until there is no further change in mass Report down your observations from Experiment 1 and explain what is happening. Write down your observations from Experiment 2 and answer the following questions: How effectively were you able to separate the two solids? What was the difference between the solids which allowed them to be separated in this way? Why would the techniques used in Week 1 not be effective for this separation? Write down your observations from Experiment 3 and explain what is happening Write down your observations from Experiment 4 and evaluate the effectiveness of this technique as a way of separating the two solids Write down your observations from Experiment 5 and explain what is happening Calculate the value of x in CuSO4.xH2O Week 3 – Solubility and Solubility Curves Chemical Principles The solubility of a substance is the quantity of that substances (in grams or moles) which can dissolve in a stated amount of solvent or solution (usually 100 ml or 1 dm3) at a given temperature. A solubility curve is a graph of solubility against temperature and hence shows the relationship between solubility and temperature. The solubility of most salts increases with increasing temperature, although there are a number of exceptions. In a small number of cases, the solubility of a substance may increase with increasing temperature up to a certain critical temperature, and then decrease again if the temperature is increased further; this happens if the most stable form of the solid changes - for example, sodium sulphate is most stable in hydrated form (Na2SO4.10H2O) at temperatures below 32.4 oC but in anhydrous form at temperatures above 32.4 oC; its solubility in water increases with increasing temperature up to a maximum at 32.4 oC but decreases with increasing temperature above 32.4 oC. The temperature of maximum (or minimum) solubility is called the transition It occurs at the same temperature for all solvents.
chem_114_-_experimental_chemistry_i.docx