Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
A mixture consists of two or more substances (elements or compounds) mixed together without any chemical bond. The components of a mixture retain their original properties.
Homogeneous Mixtures: These have a uniform composition throughout. The particles are smaller than m ( nm) in diameter. Examples include sugar in water, air, and alloys like brass.
Heterogeneous Mixtures: These have a non-uniform composition where the components can often be seen with the naked eye or under a microscope. Examples include sand and salt, oil and water.
Suspensions: A heterogeneous mixture in which the solute particles do not dissolve but remain suspended throughout the bulk of the medium. Particle size is greater than nm. They show the Tyndall effect when particles are suspended, but settle down over time.
Colloids: A heterogeneous mixture that appears homogeneous because the particle size ( nm to nm) is too small to be seen by the naked eye. They are stable and exhibit the Tyndall effect (scattering of a beam of light).
Tyndall Effect: The phenomenon of scattering of a beam of light by colloidal particles or particles in a fine suspension, making the path of light visible.
📐Formulae
💡Examples
Problem 1:
A solution contains g of common salt in g of water. Calculate the concentration in terms of mass by mass percentage of the solution.
Solution:
\begin{array}{r} 50 \ + 450 \ \hline 500 \end{array}
Explanation:
To find the mass percentage, we first calculate the total mass of the solution by adding the solute and solvent. Then, we divide the mass of the solute by the total mass and multiply by .
Problem 2:
Identify the type of mixture for the following: (i) Lemonade, (ii) Chalk powder in water, (iii) Milk.
Solution:
(i) Lemonade is a Homogeneous Mixture (Solution). (ii) Chalk powder in water is a Suspension (Heterogeneous). (iii) Milk is a Colloid (Heterogeneous).
Explanation:
Lemonade has a uniform composition. Chalk powder does not dissolve and settles at the bottom, making it a suspension. Milk appears uniform but contains tiny droplets of fat and protein dispersed in water, making it a colloid.