9th Class Chemistry Unit 13 Laboratory and Practical Skills Long Questions and Answers

1.Explain hazards due to explosive and toxic chemicals.

Hazards due to explosive and toxic chemicals can be significant and include the following:

i. Explosive Chemicals: Chemicals that cause a sudden release or pressure, gas and heat when they experience sudden shock are called explosive chemicals.

Examples of chemicals which are expected to explode are picric acid, 2,4 -di-nitrophenyl hydrazine, benzoyl peroxide, nitrocellulose etc.

Hazards This can lead to violent explosions, causing serious injuries, property damage, and even fatalities. Explosive chemicals often require special handling and storage to minimize the risk of accident.

ii. Toxic Chemical: A toxic chemical is a poisonous material which is capable of causing serious health problems

Examples Mercury, benzene, chlorine, pesticides, ammonia, hydrogen cyanide are some examples of toxic chemicals.

Hazards Exposure to toxic chemicals can have severe health effects, including respiratory tissues, skin irritation, neurological damage, or even death. Toxic substances can enter the body through inhalation, ingestion, or skin contact. Proper labeling, storage, and the use of personal protective equipment (PPE) are essential to protect individuals working with these materials.

2.Write down five such common safety instructions which are used to avoid all types of hazards.

There are five common safety instructions to avoid hazards associated with explosive and toxic chemicals:

Always use appropriate PPE(Personal Practice Equipment) such as gloves, goggles and lab coats to protect against chemical exposure.
Store chemicals in designated areas, guidelines for compatibility and ensuring containers are clearly labeled to prevent accidental mixing.
When working with volatile or toxic substances, use fume hoods to minimize inhalation risks and ensure adequate ventilation.
Keep open flames away from areas where flammable or explosive chemicals are present to prevent ignition and explosions.
Familiarize yourself with emergency procedures, including evacuation routes, first aid measures and the location of safety equipment like eyewash stations and fire extinguishers.

3.Explain the importance of warning signs and symbols to avoid any accident in the lab.

Use of Hazard Signs

Several signs and symbols are posted in different areas of the lab and bottles containing hazardous chemicals. These signs indicate that specific precautions must be observed according to the requirement sign posted there. If you see such signs, you must be alert and take extra care to maintain safety in that area.

Importance

A chemical laboratory is a strict area where rigorous rules must be practiced to avoid a chance of a deadly accident. A dangerous situation may arise not only for the individuals working there but for the whole area. In a laboratory there are several hazardous materials, sensitive equipments and specified areas for specific tasks. Proper warning signs ought to be posted on these areas to ensure that every person entering there must understand and act accordingly to maintain laboratory safety.

4.Name some toxic chemicals. Describe the effects of spreading toxic gas in the lab.

Definition of Toxic chemicals A toxic chemical is a poisonous material which is capable of causing serious health problems.

Examples Some common toxic chemicals include: Mercury, Benzene, Chlorine, Pesticides, Ammonia hydrogen cyanide.

Effects

Chlorine Gas This gas can cause problem distress, throat irritation and coughing. High concentrations can lead to severe lung damage.

Ammonia Exposure can cause irritation of the eyes, skin and respiratory tract. Inhalation of high levels can result in serious health issues or even death.

Carbon Monoxide This colorless, odorless gas can lead to headaches, dizziness, confusion and at high levels, it can be fatal due to lack of oxygen in the bloodstream.

Hydrogen Sulphide This gas has a characteristic rotten egg smell and can cause irritation of the eyes and respiratory system. High levels can lead to unconsciousness and death.

Formaldehyde Exposure can cause respiratory issues, skin irritation and is also a known carcinogen.

5.A student has spilled over a corrosive and explosive chemical due to an accident. Which emergency measures you will take to tackle the situation.

In the event of a spill involving a corrosive and explosive chemical, the following emergency measures should be taken:

Immediately clear the area of all personnel to ensure safety. Make sure everyone is at a safe distance from the spill.
Notify your lab supervisor or safety officer about the spill. Ensure that there are no open flames, sparks or any potential sources of ignition nearby, as this could trigger an explosion.
If it is safe to do so, put on appropriate PPE, such as gloves, goggles, and a lab coat, before approaching the spill.
Follow your institution's established protocols for chemical spills which may include using specific neutralizing agents or disposal methods.

6.A few decades ago, a tanker carrying poisonous chlorine gas leaked and the gas spread over a large area in Lahore. The accident killed a few persons as well as animals. Give some concrete proposals to avoid such an accident in future.

To prevent future accidents like the chlorine gas leak in Lahore, several concrete proposals can be implemented:

Enforce stricter regulations on the transport of hazardous materials. This includes using specialized tankers designed to contain leaks and withstand accidents.
Conduct routine inspections of vehicles used for transporting hazardous materials to ensure they meet safety standards and are in good condition.
Provide comprehensive training for emergency responders and local communities on how to handle hazardous material spills effectively.
Educate the public about the dangers of hazardous materials and the steps to take in case of an emergency. This can help reduce panic and improve response times.
Implement real-time monitoring systems for detecting gas leaks during transportation. This can include sensors that alert authorities immediately if a leak is detected.
Enforce laws that require safe storage practices for hazardous materials, including proper containment systems and regular maintenance checks.
Work with environmental and safety experts to develop best practices for handling and transporting hazardous materials, ensuring that the latest safety measures are in place.

7.Define chemistry laboratory? Give the precautions for students working in the laboratory?

Chemistry laboratory A chemistry laboratory is a place where a student is trained to observe the physical and chemical characteristics of substances.

Precautions of Students

i. Before starting the laboratory work, a student should get himself familiarized with the layout of the laboratory and various fittings provided in the laboratory table as well as the side shelves.

ii. Students are expected to conduct themselves in a responsible manner at all times in the lab.

iii. They are advised not to work alone in the lab.

iv. Experiments should be performed in the presence of lab instructor and other laboratory staff.

v. All equipments should be checked before use whether they are working properly according to the requirements of the experiments.

vi. Determine the potential hazards related to any equipment or the experiment before beginning any work.

vii. Appropriate safety precautions must be observed at all cost. There must not be any crowding in the lab and students should stick to their work places at a safe distance from each other

viii. Don't bring any food items in the lab. Never taste or smell any compound or a gas. If it is necessary to smell a gas it is always advised to waft the fumes or vapor towards your nose.

8.What are flammable and explosive chemicals? Give their safety instructions.

Explosive Chemicals Chemicals that cause a sudden release of pressure, gas and heat when they experience sudden shock are called explosive chemicals.

Examples of chemicals which are expected to explode are picric acid, 2,4 -di-nitrophenyl hydrazine, benzoyl peroxide, nitrocellulose etc.

Flammable Chemicals Flammable chemicals or mixtures are those which have a flashpoint around room temperature.

Examples of flammable compounds are ethers, methylated spirit, benzene, acetone, petrol etc.

Safety instructions Avoid using a chemical that is hazardous. Look for its alternative. If you must use a potentially dangerous chemical, you must follow the underlying safety instructions.

i. Obtain prior approval from your teacher.

ii. Always use smallest quantity of the chemicals.

iii. Always conduct experiment in fume hood.

iv. Remove all other chemicals and apparatus around you.

v. Inform other people working with you.

vi. Always wear safety spectacles, gloves and lab coat.

vii. Always keep flammable compounds away from heat source.

viii. Pour the flammable liquid very carefully.

ix. Properly dispose off any hazardous waste.

x. Do not store flammable liquid in refrigerator

Laboratory and Practical Skills — Long Questions