Question

ou will analyze four substances in this lab. Based on their chemical formulas and what you already know about covalent and ionic compounds, make a prediction for each compound.

Oil, which is built from the nonmetals hydrogen, carbon, and oxygen:
Cornstarch, a carbohydrate consisting of hydrogen, carbon, and oxygen:
Sodium chloride (table salt), whose formula is NaCl:
Sodium bicarbonate (sodium bicarbonate), whose formula is NaHCO3:

Answer 1

Here are short predictions and the reasons for each, based on their formulas and what we know about ionic vs covalent bonding:

1. Oil (made of H, C, O)
- Prediction: Predominantly nonpolar covalent molecules; oil will not dissolve in water, will be hydrophobic and usually a liquid at room temperature; it will not conduct electricity.
- Why: Oil molecules are long hydrocarbon chains or rings with few polar groups, so intermolecular forces are London dispersion forces rather than ionic or strong hydrogen bonds.

2. Cornstarch (a carbohydrate of H, C, O)
- Prediction: Covalent polymer (amylose/amylopectin). Granular solid that does not freely dissolve in cold water (but can swell/gel on heating); it will not conduct electricity.
- Why: Starch is a large covalent polysaccharide with many hydroxyl groups. Individual sugar monomers are polar and water-soluble, but the large polymer is only partially dispersible and forms suspensions/gels rather than giving free ions.

3. Sodium chloride (NaCl)
- Prediction: Ionic solid (crystalline). Insoluble as a solid in nonpolar solvents, readily soluble in water; does not conduct as a solid but conducts electricity when molten or dissolved (because of mobile Na+ and Cl– ions). High melting/boiling points, brittle crystal.
- Why: Na (metal) + Cl (nonmetal) form an ionic lattice of Na+ and Cl–.

4. Sodium bicarbonate (NaHCO3)
- Prediction: Ionic solid composed of Na+ and HCO3–. Soluble in water and will conduct when dissolved; gives a mildly basic (buffered) aqueous solution. Decomposes on strong heating or with acid (acid + HCO3– → CO2 gas).
- Why: Contains a metal cation and a polyatomic anion (bicarbonate), so bonding is ionic; bicarbonate can act as a base/acid (carbonate chemistry) and releases CO2 on acidification or heating.

If you want, I can turn these into specific lab predictions (appearance, behavior in water, conductivity test outcome, reaction with acid, thermal decomposition).