Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
Chemistry is the branch of science that deals with the study of the composition, properties, and structure of matter, such as (water) and (common salt).
Laboratory apparatus are primarily made of 'Pyrex' or 'Borosil' glass because it is transparent, easy to clean, and resistant to high temperatures and chemicals.
The Test Tube is used for heating small amounts of chemicals and observing reactions. A specialized 'Boiling Tube' made of hard glass is used for extreme heating.
Beakers are used for mixing, stirring, and heating larger volumes of liquids. They usually have a 'spout' for easy pouring.
Flasks come in different shapes: The Conical Flask is ideal for mixing without spilling, while the Round-bottomed Flask is used for gas preparation and heating where uniform heat distribution is required.
A Measuring Cylinder is used to measure the volume of liquids accurately, typically graduated in milliliters ().
The Bunsen Burner is the primary source of heat in the lab, consisting of a burner tube, an air hole, and a gas inlet.
A Tripod Stand and Wire Gauze are used together to support glassware during heating. The wire gauze, often containing an asbestos center, ensures even distribution of the flame.
A Retort Stand is used to hold and clamp other apparatus like burettes or flasks in a fixed position.
📐Formulae
💡Examples
Problem 1:
Which apparatus would a student use to measure exactly of a liquid, and how should they read the measurement?
Solution:
A Measuring Cylinder should be used.
Explanation:
To get an accurate reading, the cylinder must be placed on a flat surface and the student's eye must be level with the 'lower meniscus' (the bottom of the curved surface) of the liquid.
Problem 2:
Why is a wire gauze placed between the glass flask and the flame of a Bunsen burner?
Solution:
To prevent the glass from cracking due to 'thermal shock' or uneven heating.
Explanation:
The wire gauze spreads the heat from the flame evenly across the bottom of the flask, ensuring the glass does not break from a concentrated .
Problem 3:
If a sample of a liquid has a mass of and occupies a volume of in a measuring cylinder, calculate its density.
Solution:
Explanation:
Using the formula , we divide the mass by the volume to find the density of the substance.