Measurements ,measuring tools and their uses

measurements

1. Measurements

2. Mass Is the amount of matter inside an object Unit : Kg, gm Using Sensitive Balance (top load balance)

3. Volume Is the space occupied by an object. Unit: Cm, L, ml It can be measured by different tools according to the accuracy needed . 3 Measuring Cylinder Pipette Burette Gas syringe

4. Correct way of reading volume The base of the measuring cylinder must be placed on a flat surface The liquid inside the cylinder has a curvature called the meniscus . You measure the volume at the bottom of the meniscus

5. The meniscus of all liquids is curved downwards except mercury is curved upwards

6. Temperature Thermometer is used to measure temperature in Celsius . The liquid mercury inside it expands when gets hotter and contract when the temperature falls .

7. Time It is measured with a stopwatch or stop clock in seconds (sec)

8. Apparatus used in the laboratory The glass apparatus or tools that are used in the lab are made from Pyrex Glass is Inert (doesn’t react)

9. Lab Safety Rules Follow all written and verbal instructions carefully. Do not touch any equipment , chemical , or other materials in the lab. Area until you are instructed to do so. Food and drinks are not allowed inside the laboratory. Always work in a well ventilated area . Dispose of all chemical waste properly.

10. Keep hands away from face, eyes, mouth and body while using chemicals or lab equipment. Wash your hands with soap and water after performing all experiments. Wearing safety goggles is a must while working in the lab

11. Dress properly, long hair must be tied back, and loose or baggy clothes are a hazard in the laboratory. Never return unused chemicals to their original container. Never remove chemicals or other materials from the laboratory area.

12. Important rules to be safe in the lab Wear lab coat Wear goggles Wear gloves

13. Hazard Symbols

14. Explosive A chemical can explode