Source of laboratory gas – cracking process Common “laboratory gas” supplied to burners in teaching labs is typically produced industrially by the cracking of which petroleum fraction?

Introduction / Context:
Laboratory gas, used in Bunsen and Tirrill burners where piped natural gas is unavailable, is produced by thermal cracking of middle-distillate petroleum fractions to generate a combustible gas mixture. Understanding its origin helps in safety and supply planning for laboratories.

Given Data / Assumptions:

• Cracking converts higher hydrocarbons into lighter gases.
• The target is a steady, clean-burning gaseous fuel with adequate calorific value.
• Feedstocks may vary; traditional practice emphasizes certain fractions.

Concept / Approach:
Among petroleum cuts, kerosene is a common feed for portable gas generators used historically in laboratories and field setups. Thermal cracking of kerosene produces a mix of light hydrocarbons (e.g., methane to butenes) suitable for lab burners after cooling and scrubbing. Heavier feeds like fuel oil are less suitable for compact cracking units; gasoline is already volatile and typically not cracked for this purpose; diesel is heavier and produces more coke under simple cracking conditions.

Step-by-Step Solution:

Verification / Alternative check:
Older laboratory gas generators and field references cite kerosene cracking as a standard method to produce a consistent lab gas stream.

Why Other Options Are Wrong:

• Gasoline: Already light and volatile; not typically cracked for lab gas.
• Diesel/Fuel oil: Heavier; simple cracking yields more coke and operational issues.

Common Pitfalls:
Confusing “laboratory gas” with bottled LPG or natural gas; the question refers to gas produced by cracking for lab burners.

Final Answer:
kerosene