Which of the substances listed here represent a heterogeneous mixture? Choose all that apply.
A The air in the classroom B beef stewC mouthwash D chocolate padding
The Correct Answer and Explanation is:1
To determine which substances represent a heterogeneous mixture, we need to understand what a heterogeneous mixture is. A heterogeneous mixture is one in which the components are not uniformly distributed and can often be distinguished from one another. In contrast, a homogeneous mixture is one in which the components are evenly distributed at the molecular level.
Let’s break down a few common substances and identify whether they are heterogeneous or homogeneous:
- Sand and Water: This is a heterogeneous mixture. Sand is a solid and water is a liquid. The sand particles do not dissolve in the water and can be visibly separated. The composition of the mixture varies throughout, with distinct sand particles that you can see and remove.
- Oil and Water: This is also a heterogeneous mixture. Oil and water do not mix uniformly because oil is less dense than water and forms a separate layer. You can clearly see two distinct layers of liquid in the mixture.
- Salt and Water: This is a homogeneous mixture, specifically a solution. Salt dissolves completely in water, creating a uniform mixture where you can’t see the individual salt particles. The salt and water are evenly mixed at the molecular level.
- Air: This is a homogeneous mixture. Although air contains different gases like oxygen, nitrogen, and carbon dioxide, the gases are evenly mixed and cannot be distinguished by the naked eye.
- Salad: This is a heterogeneous mixture. A salad contains different ingredients (lettuce, tomatoes, cucumbers, etc.) that are not uniformly mixed. You can easily identify and separate the different components.
- Chocolate Chip Cookie Dough: This is a heterogeneous mixture because the chocolate chips and dough are not uniformly distributed. The dough and chocolate chips can be distinguished from each other.
So, the heterogeneous mixtures from the list are sand and water, oil and water, salad, and chocolate chip cookie dough.
