Question 1

What temperature range can a Bunsen burner achieve compared to a hot plate?

Accepted Answer

A Bunsen burner produces temperatures between 250-1200 degrees Celsius with an adjustable open flame, while a hot plate generates heat through electricity with temperatures ranging from 50-350°C, or up to 1250°C with special models. Hot plates offer more precise temperature control and eliminate open flame hazards.

Question 2

Why is liquid nitrogen more hazardous than dry ice in laboratory settings?

Accepted Answer

Liquid nitrogen reaches -196°C and expands 695 times its volume upon vaporization, causing extreme oxygen deficiency that can lead to suffocation and death. It also causes rapid frostbite on skin contact and permanent eye damage from brief exposure, whereas dry ice at -78°C primarily causes cold burns and carbon dioxide buildup.

Question 3

What personal protective equipment should you wear when working with hot sources?

Accepted Answer

Wear a lab coat, safety glasses, close-toed shoes, and gloves when working with hot sources. Consider thermal protective gloves that insulate effectively up to 650°C. Remove jewelry and tie back long hair to prevent contact with flames or heated surfaces.

Question 4

How should you store dry ice to minimize hazards?

Accepted Answer

Store dry ice in a polystyrene container in a cold room with proper ventilation to minimize sublimation and prevent carbon dioxide buildup. Never use airtight containers, as expanding gas from subliming dry ice can cause explosion. Dispose of cooling baths in hazardous waste containers, never in sinks or trash.

Question 5

What precautions are necessary when using a Schlenk line with liquid nitrogen?

Accepted Answer

When immersing a cold trap in liquid nitrogen while air is being pulled, oxygen can condense into the trap, creating explosive mixtures with organic materials. Extra precaution is required to prevent this hazardous condition. Always ensure proper ventilation and follow handling air and water sensitive chemicals using a schlenk line protocols.

Question 6

What is the correct first aid response for a skin burn from a hot source?

Accepted Answer

Hold the affected area under cold water for at least 10 minutes. Do not rub the area. Apply a sterile dressing and seek further medical attention. For cold burns, use tepid water instead of cold water for at least 10 minutes before applying a sterile dressing.

Question 7

Why should you never leave a Bunsen burner or hot plate unattended during operation?

Accepted Answer

Unattended hot sources pose significant fire hazards and can cause injuries if equipment malfunctions or combustible materials ignite. Before using any hot source, locate fire extinguishers and fire blankets, remove flammable materials, and maintain constant supervision to respond immediately to emergencies.

Working with Hot and Cold Sources - Assessment Quiz