Aim
To deduce the type of bonds in a compound by investigating the properties.
Method
We did several experiments to find what bonds the compounds have.
∙ Appearance
We looked at the compound and recorded if it was crystal like and the colour.
∙ Melting point
We placed the compound in a test tube and held it over a Bunsen burner. We watched to see how long the compound took to melt.
∙ Solubility
We placed the compound in water and stirred it and looked to see if any had dissolved. We then placed the compound in propanone to see if any dissolved.
∙ Electrical conductivity
We placed the compound in water, if it dissolved we placed a probe in it and passed an electrical currant through it and watched to see if the bulb lighted up.
Results
Conclusion
To conclude which compound has what bonds we look at the results and compare them to what properties create ionic and covalent compounds. The ionic compounds will have a crystal shape, they will be soluble in water but not propanone. They will have a high melting point and will pass electricity through them when dissolved in water. Covalent compounds can be splic into two, the simple molecule and a giant lattice. The simple molecule has a low melting point its usually insoluble in water but soluble in propanone. The giant lattice has a very high melting point and its insoluble in both water and propanone. Both don’t conduct electricity.
Potassium carbonate has a very high melting point meaning it could be either a ionic or a giant lattice. But it doesn’t conduct electricity and isn’t soluble in propanone. There is more evidence that this compound is a giant lattice.
Sodium chloride has a high melting point meaning it could be either a ionic or a lattice compound and as it is soluble in water, it conducts electricity and it is a crystal like compound. This concludes that it is an ionic compound
Silicon dioxide has a high melting point meaning it could be either an ionic or a lattice compound but as it is insoluble in water and propanone and doesn’t conduct electricity it concludes it has covalent bonds and is a giant lattice.
Paraffin has a low melting point meaning it is likely to be a simple covalent compound and as it isn’t insoluble in water and doesn’t conduct electricity it concludes it is. Even though simple covalent compounds are soluble in propanone my results say it doesn’t, this could be due to me putting too much of the compound in the propanone.
Sucrose has a low melting point meaning it is likely to be a simple covalent compound but as it is soluble in water, not in propanone, it conducts electricity and is a crystal like compound there is more evidence it is and ionic compound.
