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Lab Safety and Procedures
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Lab Safety and Procedures
Lab Safety and Procedures
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1
Question
What safety measure should be taken when handling corrosive materials?
Answer
Wear appropriate skin and eye protection, use the weakest concentration possible, handle in a chemical fume hood, use secondary containers, always add acids to water slowly.
2
Question
What should you do with broken or cracked glassware?
Answer
Dispose of it into the marked containers in the laboratory (red bin).
3
Question
What should you do with unused materials, equipment, and apparatus before leaving the lab?
Answer
Return them to their proper storage locations.
4
Question
Why is it important to hold a reagent bottle with the label facing you when placing it back in the rack?
Answer
To ensure you can easily identify the chemical and prevent errors.
5
Question
What type of flame is usually employed to heat solutions?
Answer
Type 3: Partially opened air hole - inner blue cone with luminous tip, outer non-luminous zone.
6
Question
How do you measure accurately the volume of a liquid delivered from a burette?
Answer
By reading the meniscus before and after delivery, keeping the eye at the same level as the bottom of the meniscus.
7
Question
How should a volumetric flask be handled to avoid thermal expansion?
Answer
Only by the neck.
8
Question
What should you do before leaving the laboratory?
Answer
Wash your hands thoroughly and leave behind protective clothing.
9
Question
What is the purpose of using a fluted filter paper?
Answer
For filtering compounds in organic solvents.
10
Question
How are cathode rays produced in a Crookes tube?
Answer
Cathode rays are emitted from the negatively charged plate (cathode) when a significant voltage difference is applied in a Crookes tube.
11
Question
Why is the end of a Crookes tube coated with fluorescent material?
Answer
The fluorescent material glows when struck by cathode rays, making them visible.
12
Question
What are the main precautions to take when working with cathode ray tubes?
Answer
Electrical shock due to high voltage equipment, and preventing current flow when not observing the properties of cathode rays.
13
Question
What does the metallic cross experiment in Experiment I demonstrate about cathode rays?
Answer
Metallic cross casting a shadow demonstrates that cathode rays travel in straight lines.
14
Question
What does the paddle wheel experiment in Experiment II demonstrate about cathode rays?
Answer
Paddle wheels turning indicate that cathode rays have momentum and kinetic energy.
15
Question
What does the behavior of cathode rays in an electric field (Experiment III) demonstrate?
Answer
Deflection of cathode rays towards a positively charged plate indicates that they are negatively charged.
16
Question
What does the deflection of cathode rays by a magnet (Experiment IV) demonstrate?
Answer
Deflection of cathode rays by a magnetic field demonstrates that they are charged particles and have magnetic properties.
17
Question
Briefly explain the difference among covalent bonding, ionic bonding and metallic bonding.
Answer
Ionic bonding involves the transfer of electrons, covalent bonding involves sharing of electrons, and metallic bonding involves a 'sea' of electrons.
18
Question
Write VSEPR theory and deduce the structure of molecules and ions giving suitable examples.
Answer
VSEPR theory predicts the shapes of molecules based on minimizing electron pair repulsion around a central atom.
19
Question
What precautions should be taken when handling glassware in a chemistry laboratory?
Answer
Glassware should be inspected for cracks/breakages, cleaned properly to ensure accurate results, and handled carefully to avoid sudden temperature changes.
20
Question
How do you use a four-beam balance to measure weight?
Answer
Move the sliders until the balance reads zero. Read each of the sliders and add their weights together.
21
Question
What is the purpose and precautions for using a stoppered bottle in a chemistry lab?
Answer
Glassware such as stoppered bottles are used for storing reagents. Precautions include proper labeling and avoiding contamination.
22
Question
What is the purpose and precautions for using a wash bottle in a chemistry lab?
Answer
A wash bottle is used for rinsing glassware and dispensing distilled water. Precautions include using distilled water and avoiding contamination.
23
Question
What is the purpose and precautions for using a funnel in a chemistry lab?
Answer
Funnel is used to transfer liquids or solids into containers with small openings. Ensure it is clean and properly positioned.
24
Question
What is the purpose and precautions for using a measuring cylinder in a chemistry lab?
Answer
A measuring cylinder is used for approximate volume measurements. Precautions include reading the meniscus at eye level and avoiding parallax errors.
25
Question
What is the purpose and precautions for using a pipette in a chemistry lab?
Answer
A pipette is used for accurate volume measurements and transferring liquids. Precautions include using a pipette filler, cleaning the pipette before use, and reading the meniscus correctly.
26
Question
What is the purpose and precautions for using a burette in a chemistry lab?
Answer
A burette is used for accurate dispensing of variable volumes of liquids, especially in titrations. Precautions include proper cleaning, filling below eye level, and accurate reading of the burette.
27
Question
What is the purpose and precautions for using droppers in a chemistry lab?
Answer
Droppers are used for dispensing small volumes of liquids dropwise. Precautions include avoiding contamination and controlling drop size.
28
Question
Name primary standard substances that could be used to prepare solutions with accurate concentrations.
Answer
Primary standard substances are substances that can be used to prepare solutions with accurate concentrations.
29
Question
List reactions that liberate oxygen under laboratory conditions.
Answer
Reactions that liberate oxygen under laboratory conditions include the decomposition of potassium permanganate.
30
Question
Why is cotton wool inserted into the boiling tube during the oxygen gas collection experiment?
Answer
Cotton wool is inserted into the boiling tube to prevent KMnO4 particles from being carried over into the collection apparatus.