The purpose of this experiment was to explore the properties of chemical substances that can be used to identify the types of bonds in a chemical substance using a laboratory procedure. The two types of bonds being identified were ionic and covalent. Based on a substance’s properties, how can you determine whether its bonds are ionic or covalent? This is the question I posed before starting the experiment. An ionic bond is a bond that results from the attraction between oppositely charges ions; one atom “gives” another atom an electron. Combinations of metals and nonmetals typically form ionic bonds. A covalent bond is a bond that results from the sharing of pairs of electrons between two atoms. This kind of bond generally involves nonmetals. Both bonds, ionic and covalent, have properties that distinguish them.
Ionic compounds have high melting and boiling points making them solid at room temperature. They are also soluble in polar solvents (such as water), have crystalline structures, and conduct electricity well. On the other hand, covalent compounds are usually liquid or gaseous at room temperature, resulting from their low melting and boiling points. They are poor conductors of electricity and are usually soluble in non-polar liquids (liquids other than water). If a substance is solid at room temperature, has a crystalline structure, dissolves easily in water, and conducts electricity well, then it likely contains ionic bonds. Otherwise, it likely contains covalent bonds.
This was the hypothesis I posed at the beginning of the experiment. The independent variables used in this experiment were the tested substances (oil, cornstarch, sodium chloride, and sodium bicarbonate). The dependent variables in this experiment were the concluded properties of said substances. These included state of matter, appearance and texture, whether or not it had a crystalline structure, level of solubility in water, level of conductivity, and if it contained ionic or covalent bonds. There were no controlled variables used in this experiment.
Analysis and Conclusion:
My data mostly supported my hypothesis. The hypothesis I posed at the beginning of this experiment was: If a substance is solid at room temperature, has a crystalline structure, dissolves easily in water, and conducts electricity well, then it likely contains ionic bonds. Otherwise, it likely contains covalent bonds. My data did not completely support my hypothesis because cornstarch was concluded to have covalent bonds even though it is solid at room temperature. This refutes my hypothesis because I said if a substance is solid at room temperature, it must contain ionic bonds. Sodium chloride, sodium bicarbonate, and oil all supported my hypothesis, though.
I concluded that sodium chloride and sodium bicarbonate contained ionic bonds because they both conducted electricity and were solid at room temperature. I concluded that oil contained covalent bonds because it did not dissolve in water, was a liquid at room temperature, and did not conduct electricity. Possible ways to improve this investigation would be to test more substances, and further experiment with the substances that were already tested in this experiment. This would give more data to further support or refute my hypothesis. The level of accuracy significantly increases in an experiment when more data becomes available to analyze. Possible sources of error could have been improper measurements, cross-contamination of substances, and accidentally writing wrong information in the data table.