Question

1. a student has two compounds in two separate bottles but with no labels on either one. one is an unbranched alkane, octane, c₈h₁₈; the other is 1 - hexene, an unbranched alkene, c₆h₁₂. based on your observations in this experiment, tell what you should see in the following tests:

a. water solubility

b. ligroin solubility

c. combustion

d. density versus water

e. bromine test

f. permanganate test

Explanation:

Step1: Water - solubility principle

Both octane and 1 - hexene are non - polar hydrocarbons. Water is a polar solvent. Non - polar substances are insoluble in polar solvents due to the "like dissolves like" principle.
Octane: Insoluble
1 - Hexene: Insoluble

Step2: Ligroin - solubility principle

Ligroin is a non - polar solvent. Non - polar hydrocarbons are soluble in non - polar solvents.
Octane: Soluble
1 - Hexene: Soluble

Step3: Combustion characteristics

Octane is an alkane with a higher carbon - hydrogen ratio compared to 1 - hexene. Alkanes burn with a relatively clean flame, while alkenes burn with a smokier flame due to the higher carbon content per hydrogen in alkenes.
Octane: Burns with a clean flame
1 - Hexene: Burns with a smokier flame

Step4: Density comparison with water

Both octane and 1 - hexene are less dense than water. Hydrocarbons generally have lower densities than water.
Octane: Less dense than water
1 - Hexene: Less dense than water

Step5: Bromine test principle

Alkenes react with bromine in an addition reaction, causing the bromine color to fade. Alkanes do not react with bromine under normal conditions.
Octane: No reaction, bromine color remains
1 - Hexene: Bromine color fades

Step6: Permanganate test principle

Alkenes react with potassium permanganate in an oxidation reaction, causing the purple color of permanganate to fade. Alkanes do not react with potassium permanganate under normal conditions.
Octane: No reaction, purple color remains
1 - Hexene: Purple color fades

Answer:

a. Octane: Insoluble; 1 - Hexene: Insoluble
b. Octane: Soluble; 1 - Hexene: Soluble
c. Octane: Burns with a clean flame; 1 - Hexene: Burns with a smokier flame
d. Octane: Less dense than water; 1 - Hexene: Less dense than water
e. Octane: No reaction, bromine color remains; 1 - Hexene: Bromine color fades
f. Octane: No reaction, purple color remains; 1 - Hexene: Purple color fades