Introduction: (Initial Observation)
Many materials in nature are in the form of a mixture of two or more chemicals. Separation of materials and extraction of one substance from a mixture is a common process in every chemical factory. Extraction of pure sugar from sugar cane, extraction of sodium chloride and magnesium chloride from salty waters, and extraction of gasoline from crude oil are examples of such separations. In this project we will try to find our if it is possible to extract water from Ink, Vinegar and Milk.
Many science projects are attempts to solve certain problems. That is why you may want to have a problem statement instead of question or purpose. This is a sample problem statement for this project.
High cost of transportation and storage of liquids is a major problem for manufacturers and distributors. If we know what liquids can be dehydrated, we can dehydrate them and make concentrations that need less space and will cost less for storage and transportation. We can later dilute them by water at the destination and shortly before use or consumption.
Find out about separation of material. Read books, magazines or ask professionals who might know in order to learn about the separation techniques. Keep track of where you got your information from.
Although extracting a pure substance from a mixture is done by chemists and in chemical factories, often physical properties of material are the key in such separations. Differences in physical properties such as the boiling point, melting point, density and solubility can help us to separate many substances from a mixture.
Physical properties of our subject material are: (From Chemical Dictionary)
1. Vinegar is a solution of about 10% acetic acid in water. Acetic acid is a colorless liquid with a melting point of 16.63º C and a boiling point of 118ºC.
2. Writing Ink is a solution of colorant in water, usually also containing a low percentage of tannic or gallic acid.
3. Milk is a heterogeneous liquid secreted by the mammary gland and composed of about 87% water, 3.8% emulsified particles of fat and fatty acid, 3% casein, 5% sugar (lactose) and small amounts of vitamins and minerals.
Distillation means vaporization of a liquid and subsequent condensation of the resultant gas back to liquid form. It is used to separate liquids from nonvolatile solids or solutes (e.g., alcoholic beverages from the fermented materials, water from other components of seawater) or to separate two or more liquids with different boiling points (e.g., gasoline, kerosene, and lubricating oil from crude oil). Many variations have been devised for industrial applications. An important one is fractional distillation, in which liquids with similar boiling points are repeatedly vaporized and condensed as they rise through an insulated vertical column. The most volatile of the liquids emerge first, nearly pure, from the top of the column, followed in turn by less and less volatile fractions of the original mixture. This method separates the mixture’s components far better than simple distillation does
Distillation is based on the fact that the vapor of a boiling mixture will be richer in the components that have lower boiling points.
Therefore, when this vapor is cooled and condensed, the condensate will contain more volatile components. At the same time, the original mixture will contain more of the less volatile material.
Distillation columns are designed to achieve this separation efficiently.
Although many people have a fair idea what “distillation” means, the important aspects that seem to be missed from the manufacturing point of view are that:
|distillation is the most common separation technique
distillation is the most common separation technique
|it consumes enormous amounts of energy, both in terms of cooling and heating requirements|
Please note: (from top) use of clips to hold apparatus together, position of the thermometer, and the clamp holding the round bottom flask in place.
Please note: from left: use of clamp to hold collection flask, white tubing is where water goes in, red tubing is where water goes out.
Distillation is probably the most common technique for purifying organic liquids. In simple distillation, a liquid is boiled and the vapors work through the apparatus until they reach the condenser where they are cooled and reliquified. Liquids are separated based upon their differences in boiling points. Two important factors to note: 1) the tip of the thermometer must be correctly positioned slightly below the center of the condenser to accurately reflect the temperature of the vapors (see above left) and 2) the water supply should be connected to the lower port in the condenser and the drainage tube connected to the upper (in the picture on the right the right tube is connected to the water supply and the red tube is a drainage tube). Also be sure to use the thin-walled tubing and not the heavy walled vacuum tubing. Be very careful that your water lines do not come in direct contact with your hot plate, as the lines could melt resulting in a flood. Be sure to clamp both the round bottom boiling flask and the collection tube. Knocking over your collection tube at the end of the experiment if VERY frustrating. Below is a diagram of assembly: Generally, boiling stones will be added to the boiling flask to ensure even boiling. It is also wise to use some type of clamps to connect the various pieces of the distillation apparatus together. For low boiling liquids, enough heat may be provided simply by resting your flask on the hot plate (as shown above). You can also insulate your boiling flask and Claisen adaptor with aluminum foil. For higher boiling liquids it may be necessary to use an oil or sand bath to reach higher temperatures. The individual pieces of glassware needed for a simple distillation are diagrammed below.
Be sure to use the blue clips to attach the vacuum adaptor and the Claisen tube and the distillation adaptor.
The setup for a fractional distillation is very similar to that for simple distillation. The only difference is the addition of a fractional distillation column, usually packed with some material of high surface area that produces a more efficient separation than the simple distillation. The same advice regarding the thermometer placement, clamping, and hook-up of the water tubes in the simple distillation also apply to the fractional distillation. As this apparatus is larger, practice additional caution to be sure that no glassware is broken or product lost. The choice whether to use the simple or the fractional setup will depend on the compounds that you are trying to separate. Obviously, the simple distillation setup is simpler and the distillation generally will be quicker than the fractional. However, the fractional setup is more efficient at separating liquids with fairly similar boiling points and at times is required.
On the left, note that the tube connected to the spigot is connected to the lower part of the
condenser, while the drainage tube is connected to the higher part. Also, note the position of the thermometer.
Please note the use of clamps to secure the round bottom flask and the collection flask.
Pictured on the left is the fractional distillation apparatus. A closer shot is on the right. Notice that the only difference between this apparatus and the simple distillation apparatus is that here, the fractional distillation column has been placed between the boiling flask and the distillation head. As in the simple distillation apparatus, not that the white tubing is connected to the water supply and the red tubing is the drainage tube. Also notice the position of the thermometer, blue clips, and clamps. A diagram of the apparatus is below.
What do you want to find out? Write a statement that describes what you want to do. Use your observations and questions to write the statement.
The purpose of this project is to investigate the separation of pure water from milk, vinegar and water based ink. We will perform experiments and report the process, problems and solutions.
Additional Option 1:
You may also calculate the amount of water that you can extract from each of the above materials.
Additional Option 2:
You may also calculate the amount of water that you can extract from each of the above materials in a certain amount of time (i.e., 1 hour).
When you think you know what variables may be involved, think about ways to change one at a time. If you change more than one at a time, you will not know what variable is causing your observation. Sometimes variables are linked and work together to cause something. At first, try to choose variables that you think act independently of each other.
The independent variable (also known as manipulated variable) is the type of liquids that you test. Possible values are milk, vinegar, soda, ink, orange juice, …
The dependent variable is the possibility of extracting water from specific liquids or the amount of water that may be extracted in a certain period of time.
Constants are experiment method and apparatus as well as distillation time.
Controlled variables are weather temperature and moisture.
Based on your gathered information, make an educated guess about what types of things affect the system you are working with. Identifying variables is necessary before you can make a hypothesis.
My hypothesis is that water can be separated from all of our test subjects by the process of distillation. This hypothesis is based on my gathered information about the boiling point of water, acetic acid and other chemicals that exist in our test samples.
Design an experiment to test each hypothesis. Make a step-by-step list of what you will do to answer each question. This list is called an experimental procedure. For an experiment to give answers you can trust, it must have a “control.” A control is an additional experimental trial or run. It is a separate experiment, done exactly like the others. The only difference is that no experimental variables are changed. A control is a neutral “reference point” for comparison that allows you to see what changing a variable does by comparing it to not changing anything. Dependable controls are sometimes very hard to develop. They can be the hardest part of a project. Without a control you cannot be sure that changing the variable causes your observations. A series of experiments that includes a control is called a “controlled experiment.”
Distillation is probably the most common technique for purifying liquids. In simple distillation, a liquid is boiled and the vapors work through the apparatus until they reach the condenser where they are cooled and re-liquefied.
In this experiment you will perform distillation experiment on different liquids and examine the resulting distillate to see if it is water. (If it looks like water and tastes like
The process is relatively simple:
a) the water based liquid is heated
b) to the boiling point and thus vaporizes
c) (becomes steam), while other substances remain in solid state, in boiler. Steam is then directed into a cooler
d) where it cools down and returns to liquid
e) and the end result is usually a purified liquid.
We can purchase a complete set of distillation apparatus from a local laboratory supplier or we can setup a simple distillation apparatus as follows:
- Use a glass test tube or flask as a boiling unit.
- Use a glass tube as condenser.
- Connect the boiling unit to the condenser via a rubber or plastic joint. It can be an elbow tube or any other rubber or plastic tube.
- Use stand and clamps or any other safe method to secure your setup like the following figure.
Heat source can be an alcohol burner, but you can also use Chafing Dish Fuel cans (sold in supermarkets for keeping food warm).
Condensed vapors can be collected in a beaker or glass cup.
Fill about one third of your test tube (or flask) with your test sample (such as milk). Connect the joints and condenser and do a final check to make sure that all connections are secure.
Bring the heat source under the test tube or flask and watch the boiling and condensation process. Collect a few milliliter of condensed liquid. What color is your condensed liquid? What is the taste of the condensed liquid? Is your condensed liquid pure water?
Repeat the process with all your samples and record the results.
- The reason that you use glass distillation apparatus is that you want to see what is happening during the distillation process. Otherwise metal pieces will do as well.
- In a simpler process, you heat up your sample in the test tube and hold a cold dish above the test tube to condense the vapors. Usually, that amount of condensation will be enough to identify the purity of the condensed water.
- A few small pieces of glass or metal at the bottom of the test tube or flask can prevent sudden, explosive boiling of your test samples.
To show that the extracted water is really from your sample liquid- not from an unknown source, you may want to setup a control experiment. The control experiment is an identical distillation apparatus with no liquid to distill. The fact that no water will get condensed and exit the control setup will show that the water produced in your experiment is in fact from the liquid you distill.
Additional Samples and Pictures:
Here we found a copper tube and matching copper elbow and used it as a condenser. The can is filled to a third with milk.
The problem was that it took a few minutes for the milk to boil.
Adult supervision and a safe experiment area is required in addition to safety goggles.
In this experiment we are using an electric heater instead of an alcohol burner.
The problem was that so much heat was being wasted, since the soda can was so small and the heater element was big.
Adult supervision and safe experiment area is required in addition to safety goggles.
Hear we used a propane torch as a heat source. Wire screen was necessary here to distribute the flame and heat.
Adult supervision and safe experiment area is required in addition to safety goggles.
In this experiment we used aluminum foil to build a condenser tube.
If alcohol burners are used, they should be filled when cold, only by an adult. Adding common salt to the wick of the burner makes it easier for you to see the flame and thus avoid possible burns. All components become quite hot during the distillation. You must be very cautious and careful in avoiding to touch the material during the collection of the distillate. Goggles must be worn throughout the experiment.
Need Results table and graph?
Measure how much water you extracted from each sample. Your results table will look like this:
|Substance name||Initial amount||Water amount||% of water|
Create a bar graph for your results. Each bar represents one of the three substances that you tested. The height of the bar is the percent of water that you extracted. Use 0.1 inch for each percentage of water. So 35% water will be a bar 3.5 inch tall.
Materials and Equipment:
As you see above, you have many different options for material that you may use for your distillation experiments. For example you may use any electric heater as your heat source and a glass distillation set including flask, condenser and adapter. All these are available from local science suppliers that you may find them from your phone directory.
In another trial experiment shown above we have used a glass test tube and an alcohol burner and wooden clamp from MiniScience.com. The plastic or rubber tubes are from a local hardware store.
In our last trial we used soda can to boil the liquid. Copper (tubes and joints) working as a condenser can be purchased from hardware stores. The support stand and alcohol burner are from MiniScience.com. These can be substituted with other things that you may have available.
Results of Experiment (Observation):
Experiments are often done in series. A series of experiments can be done by changing one variable a different amount each time. A series of experiments is made up of separate experimental “runs.” During each run you make a measurement of how much the variable affected the system under study. For each run, a different amount of change in the variable is used. This produces a different amount of response in the system. You measure this response, or record data, in a table for this purpose. This is considered “raw data” since it has not been processed or interpreted yet. When raw data gets processed mathematically, for example, it becomes results.
No calculation is required for this project.
Summary of Results:
Summarize what happened. This can be in the form of a table of processed numerical data, or graphs. It could also be a written statement of what occurred during experiments.
It is from calculations using recorded data that tables and graphs are made. Studying tables and graphs, we can see trends that tell us how different variables cause our observations. Based on these trends, we can draw conclusions about the system under study. These conclusions help us confirm or deny our original hypothesis. Often, mathematical equations can be made from graphs. These equations allow us to predict how a change will affect the system without the need to do additional experiments. Advanced levels of experimental science rely heavily on graphical and mathematical analysis of data. At this level, science becomes even more interesting and powerful.
Using the trends in your experimental data and your experimental observations, try to answer your original questions. Is your hypothesis correct? Now is the time to pull together what happened, and assess the experiments you did.
Related Questions & Answers:
What you have learned may allow you to answer other questions. Many questions are related. Several new questions may have occurred to you while doing experiments. You may now be able to understand or verify things that you discovered when gathering information for the project. Questions lead to more questions, which lead to additional hypothesis that need to be tested.
If you did not observe anything different than what happened with your control, the variable you changed may not affect the system you are investigating. If you did not observe a consistent, reproducible trend in your series of experimental runs there may be experimental errors affecting your results. The first thing to check is how you are making your measurements. Is the measurement method questionable or unreliable? Maybe you are reading a scale incorrectly, or maybe the measuring instrument is working erratically.
If you determine that experimental errors are influencing your results, carefully rethink the design of your experiments. Review each step of the procedure to find sources of potential errors. If possible, have a scientist review the procedure with you. Sometimes the designer of an experiment can miss the obvious.
Q. What are some safety risks for this project and how could I avoid those risk?
A. Since you will work with heat and hot liquids, there is always a risk of burning and fire. Take all precautions needed in working with fire and hot materials. Do your experiment in a place with proper ventilation. Some gases and vapors such as vinegar may cause irritation.