Unit 3: Topic 7 - Solutions and Mixtures

Question 1

What are homogeneous mixtures?

Answer 1

Homogeneous mixtures, also known as solutions, are uniform in composition. They can be solids, liquids, or gases, but never a combination of states.

For example, salt water is a homogeneous mixture because the salt particles are evenly distributed throughout the water.

Question 2

What are heterogeneous mixtures?

Answer 2

Heterogeneous mixtures are not uniform in composition, meaning we can see their different components.

Unlike homogeneous mixtures, heterogeneous mixtures may consist of substances in different states. For instance, a mixture of sand and water is still heterogeneous even though sand is a solid and water is a liquid. However, this is not always the case, as a mixture of oil and water is also heterogeneous, yet both components are liquids.

Question 3

What is the difference between a solute and a solvent?

Answer 3

The solute is the substance that is being dissolved in a solvent to form a solution.

For example, the solute in salt water is salt, and the solvent is water because the salt particles are being dissolved.

Question 4

What is molarity?

Answer 4

Molarity, or molar concentration, is the number of moles of solute per liter of solution. Using the formula M = n/V, where M is molarity, n is moles of solute, and V is liters of solution, we can use stoichiometry to solve for different values.

Question 5

What can we use molarity for?

Answer 5

In a laboratory, we often work with solutions and thus need to determine different quantities involving molarity.

For instance, given the molarity and volume of a solution, we can solve for the moles of solute and convert to grams or the number of solute particles using the solute’s molar mass or Avogadro’s number (6.022E23 particles/mol). This tells us the quantity of solute we must measure to form the solution with the correct molarity.

Additionally, we could solve for the volume of a solution with the molarity and amount of solute, whether given the number of particles, grams, or moles of solute. This tells us the total volume that our solution should have.

We could also find the molarity of a solution if we determine the moles of solute and liters of solution.