combustion and solubility of organic substances


Lab: Combustion and Solubility of Organic Substances

GEAR (per Group): 3 cold nickel spatulas, cyclohexane, cyclohexene, ethanol, bunsen, matches,

rack of testtubes, safety glasses

AIM: To investigate some properties of organic substances.


1. a. Take a drop of cyclohexane on the end of a cold spatula & heat in a blue flame. b. Observe. Look for colour of flame, smokiness. b. Repeat with cyclohexene, then ethanol.

2. a. Put 2mL water and 1mL cyclohexane into a testtube. b. Observe. Is it soluble or does it form a separate layer above or below water? b. Repeat with cyclohexene, then ethanol.


Observations of Combustion Observations of Solubility





1. What do all these organic substances look like? ____________________________________

2. What organic family does each substance belong to?

Cyclohexane: _______________________________

Cyclohexene: _______________________________

Ethanol: ___________________________________

3. Give the formula for ethanol : _____________________

4. a. When substances burn what are they reacting with? _____________________________ b. When a flame burns cleanly we say the combustion is ____________________________ c. What are the products in this case? ________________________ and _______________ d. Give a word equation for the substance here that burned in this way: e. Give a balanced formula equation for this same reaction: f. When the flame is sooty this tells us that combustion is ____________________________ g. Why is the flame yellow? ___________________________________________________ h. Give a word equation for such a reaction: i. Give a balanced formula equation for butane burning in this way:

5. a. Which organic substance here is soluble? ______________________________________ b. What is the term given to 2 liquids which do not mix? _____________________________ c. Which has the lowest density: alkane or water? __________________________________ d. How do you know? ________________________________________________________


1. _______________ and ______________ burn cleanly with a _____________ flame as they combust ________________________

2. ___________________ burn with a sooty flame as they combust _____________________

3. _____________________ and ___________________ are insoluble in water (they are said to be _____________________________________________)

4. __________________________ is soluble in water (although this does decrease as the molecule size gets bigger)