Filtration & Evaporation - Online Tutor, Practice Problems & Exam Prep

Filtration is the process of separating an insoluble solid from a liquid using a filter, where the solid remains on the filter paper (residue) and the liquid that passes through is called the filtrate. Two methods include simple filtration with an Erlenmeyer flask and funnel, and vacuum filtration using a Buckner funnel, which speeds up the process. Evaporation, or crystallization, separates a soluble solid from a liquid by heating, leaving solid material behind. Both techniques are essential for separating mixtures in chemistry.

Filtration-Evaporation

Hey everyone, so in the first part of this video, let's talk about filtration. Now, filtration is just the process of separating a solid from a liquid. Here, we're going to say the technique involves the separation of an insoluble solid from a liquid by its moving through a filter. We're going to be using filter paper in terms of filtration. Now, here we're going to say that the insoluble solid is left behind on the filter paper and is termed the residue. So, that solid that you get at the end stuck onto the filter paper is called your residue. And the solvent that passes through the filter paper is termed the filtrate. So here we have two examples of filtration. Both of them deal with using an Erlenmeyer flask, so both of them have this flask involved. In the first one, we're using a simple Erlenmeyer flask, and we're going to use a funnel. Within this funnel, we have our filter paper that has been folded in order to fit properly within this funnel. This filter paper kind of serves as a semi-permeable membrane. It allows the passage of our solvent or filtrate through, and then the solid actually can't pass through and it's stuck on the residue paper on the filter paper. So the residue will adhere itself to this. Now, this method is a little bit time-consuming. It takes a good amount of time. It works best if your solid is really not that dissolved within your solution. Now the second type of filtration we can have here involves a different type of flask. Here it has a vacuum pump that can be attached to it. This vacuum pump can help rush the filtrate faster through the filter paper. We're using a Büchner funnel, and of course, we still have our filter paper here where our solid can adhere to it. Now the vacuum pump's going to pull on basically cause a vacuum within our flask, which will draw out the filtrate faster. Now, this is best used if you, 1, want to do this process faster, and also it works best if your solid is more partially dissolved, because by using the vacuum pump it's actually going to decrease the temperature around the Büchner funnel. This drop in temperature will help to recrystallize the already more dissolved solid. So both of these options are different types of filtration that you can use. The first one being much simpler, the other one requiring a few more parts to it. Now a great example of everyday use of filtration involves a coffee filter. So when you put a coffee filter within your coffee machine, what does it do? It allows the coffee bean grinds or residues to remain behind on the coffee filter, and then the filtrate, which in this case is your coffee, filters through. Now that we've talked about filtration, let's look at evaporation. So evaporation, sometimes called crystallization, is the technique involved in the separation of a soluble solid from a liquid based on the boiling point of the solvent. So here, this is different. In the other ones, we had insoluble solids or solids that were a little bit more soluble. Here it's completely soluble. And here we have a Bunsen burner, and what we have here, this bowl, this is our evaporation bowl or heating bowl. And basically, if we heat this up enough, we'll be able to evaporate or vaporize the liquid portion, and what will be left behind at the end are pieces of solid material. So both of these techniques, filtration and evaporation, are just useful ways in which we can separate our liquid from our solid within a given mixture.

Here’s what students ask on this topic:

What is the difference between filtration and evaporation in chemistry?

Filtration and evaporation are both separation techniques used in chemistry, but they serve different purposes. Filtration separates an insoluble solid from a liquid using a filter. The solid left on the filter paper is called the residue, and the liquid that passes through is the filtrate. Evaporation, or crystallization, separates a soluble solid from a liquid by heating the mixture. The liquid evaporates, leaving the solid material behind. Filtration is useful for mixtures where the solid does not dissolve in the liquid, while evaporation is used when the solid is dissolved in the liquid.

How does vacuum filtration differ from simple filtration?

Vacuum filtration and simple filtration are two methods of separating an insoluble solid from a liquid. Simple filtration uses a funnel and filter paper placed in an Erlenmeyer flask. The liquid passes through the filter paper, leaving the solid residue behind. This method is time-consuming. Vacuum filtration, on the other hand, uses a Buckner funnel and a vacuum pump attached to the flask. The vacuum pump creates a pressure difference, speeding up the filtration process. This method is faster and more efficient, especially for partially dissolved solids, as the vacuum can help recrystallize the solid by lowering the temperature around the funnel.

What are some everyday examples of filtration?

Filtration is a common process in everyday life. One of the most familiar examples is using a coffee filter in a coffee machine. The coffee filter allows the liquid coffee to pass through while retaining the coffee grounds, which act as the residue. Another example is air filtration in HVAC systems, where air filters trap dust and other particles, allowing clean air to circulate. Water filtration systems also use this principle to remove impurities from water, ensuring it is safe for drinking.

What equipment is needed for evaporation in a chemistry lab?

To perform evaporation in a chemistry lab, you need several pieces of equipment. The primary items include a Bunsen burner for heating, an evaporation bowl or heating dish to hold the liquid mixture, and a tripod or stand to support the bowl above the burner. Additionally, a wire gauze may be used to distribute heat evenly. As the mixture is heated, the solvent evaporates, leaving the soluble solid behind. This method is particularly useful for separating a dissolved solid from its solvent based on their boiling points.

Why is filter paper used in filtration?

Filter paper is used in filtration because it acts as a semi-permeable membrane, allowing the liquid (filtrate) to pass through while retaining the solid particles (residue). The paper's porous structure traps the solid particles, preventing them from passing through with the liquid. This makes filter paper an essential component in separating insoluble solids from liquids in various chemical processes. Its effectiveness depends on the pore size, which can be selected based on the size of the particles being filtered.