Final answer:
During combustion analysis, a green flame indicates a liquid fuel/oxidant mixture, while a yellow flame indicates a solid fuel mixture. The CO2 and H2O produced enable measurement of carbon and hydrogen content in the sample.
Step-by-step explanation:
When performing a combustion analysis, two key observations could be made in the combustion tube.
1. If you were to introduce a liquid fuel/oxidant mixture to the combustion tube, you might observe a green flame at the 3-second mark. This indicates that the substance being combusted is likely a liquid fuel.
2. In the case of a solid mixture fuel being burned, you are more likely to see a yellow flame, which could occur at the 4-second mark. This is indicative of a more powerful engine.
The purpose of combustion analysis is to determine the carbon and hydrogen content of a sample by converting all the carbon to CO2 and all the hydrogen to H2O.
The substances are then trapped in respective traps with sodium hydroxide for CO2 and magnesium perchlorate for H2O, where their masses can be measured to determine their quantities in the sample.