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Make Iron Salts

Make Iron Salts

Introduction: (Initial Observation)

Iron sulfate has many commercial applications. It is used for correcting iron deficiency in lawns, shrubs, trees and other plants. It is also used for acidifying the soil. Iron sulfate promotes a dark green color in many plants. Some other uses of Iron Sulfate are: water and sewage treatment; catalyst; feed additive, herbicide; wood preservative and medicine. As a medicine, Iron Sulfate treats or prevents iron-deficiency anemia.

On the other hand scrap Iron is available as a byproduct of many different industries and it can be obtained free or at a very low price. In this project you investigate production of Iron Sulfate (Ferrous Sulfate) and some other Iron Chemicals.

Dear 

This project guide contains information that you need in order to start your project. If you have any questions or need more support about this project, click on the “Ask Question” button on the top of this page to send me a message.

If you are new in doing science project, click on “How to Start” in the main page. There you will find helpful links that describe different types of science projects, scientific method, variables, hypothesis, graph, abstract and all other general basics that you need to know.  

Project advisor

Information Gathering:

Find out about what you want to investigate. Read books, magazines or ask professionals who might know in order to learn about the effect or area of study. Keep track of where you got your information from.

As any other chemical related research project you will need to gather information about the uses and benefits of the product as well as its production method. Following questions can be a good start for your research:

Benefits: What are the uses and benefits of Iron Sulfate?

Market Size: How much Iron sulfate is being produced now and what is its price?

As an Intermediate: What other products/ chemicals can be made from Iron Sulfate? This is where you find out that Iron oxide, Iron Hydroxide and Ammonium Iron Sulfate are among the chemicals that can be made from Iron Sulfate.

Production method: How can Iron sulfate be made? Is it a byproduct of some other industries? What are the different ways that Iron Sulfate can be made? I am wondering if it can be made from the reaction of sulfuric acid with Iron ore.

You need to gather such information from commerce and Industry related government organizations and technical books. Following are samples of the information that you may find:

Iron Sulfate: (ferrous sulfate, iron vitriol, copperas, green vitriol, sal chalybis) FeSO4.7H2O is a greenish or yellow-brown crystals or granules. Iron Sulfate is a byproduct from pickling of steel and many chemical operations. It can be made by action of dilute sulfuric acid on iron.

Iron Hydroxide: (ferric hydroxide) Fe(OH)3 is brown flocculant precipitate which dries to the oxide; loses water below 500ºC, soluble in acids, insoluble in water, alcohol and ether.

Iron oxide red: Iron oxide red or ferric oxide (Fe2O3) is also known as Burnt sienna, Indian red, rouge and Turkey red. Iron oxide red is used in pints, rubber products and plastics. Pure ferric oxide is also used in polishing compounds, magnetic tapes, permanent magnets and used as mordant, laboratory reagent, catalyst and feed additive.

 Iron oxide materials yield pigments that are nontoxic, nonbleeding, weather resistant, and lightfast. Natural iron oxides include a combination of one or more ferrous or ferric oxides, and impurities, such as manganese, clay, or organics. Synthetic iron oxides can be produced in various ways, including thermal decomposition of iron salts, such as ferrous sulfate, to produce reds; precipitation to produce yellows, reds, browns, and blacks.

In the year 2000 about 154,000 tons Iron oxide is manufactured in US and about 91,000 tons iron oxide is imported from other countries. Average price is about $900 per ton.

The sources of data for the iron oxide pigments worksheet are the mineral statistics publications of the U.S. Bureau of Mines and the U.S. Geological Survey-Minerals Yearbook (MYB) and its predecessor, Mineral Resources of the United States (MR).

The retail price of pure iron sulfate (food grade) is about $10/Lbs.

Medical Uses of Iron Sulfate:

Iron is a mineral that your body needs to produce red blood cells. When the body does not get enough iron, it cannot produce enough red blood cells to keep the body healthy. This is called iron-deficiency anemia. Ferrous sulfate is used to treat or prevent low levels of iron in the blood; consequently, it treats or prevents iron-deficiency anemia.

Lack of iron can cause tiredness, shortness of breath, and decreased physical performance. It also can increase a your chance of getting infections.

Foods rich in iron include lean red meat, beans, nuts, asparagus, oatmeal, and dried peaches. Vitamin C can increase the absorption of iron, which can be found in citrus fruits and fresh vegetables. Source…

Question/ Purpose:

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 perform experiment and make observation of the process of making iron sulfate, Iron hydroxide and red Iron oxide.

You may also want to investigate on certain questions. Following are some examples:

  1. How many molecules of water exists in each molecule of ferrous sulfate?
  2. How much ferrous sulfate heptahydrate can be made from 100 grams iron?
  3. What is the effect of sulfuric acid concentration on its rate of reaction with iron.
  4. What is the effect of temperature on the rate of reaction of sulfuric acid with iron?
  5. What is the pH of a normal solution of ferrous sulfate?

If you pick up any of these questions, you may need to repeat the suggested experiments with different values of your independent variable and record your data.

Identify Variables:

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.

If you are doing this project as a display or observation project, you will not need to define variables. If you choose any of the questions, then you may have to define variables. For example for question number 4 your variables are as follows:

The independent variable is the temperature of the reaction. The dependent variable is the rate of reaction. Controlled variables are type and concentration of iron and sulfuric acid as will as all experiment procedures. In other words when you are studying the effect of temperature on the rate of reaction, you want to make sure that no other factor (other than temperature) is causing changes on your results.

Hypothesis:

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.

If you have a question, you must also have a hypothesis. Following is an example:

The rate of reaction increases by the increase of temperature.

If you do this as a display project, you don’t need hypothesis.

Experiment Design:

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.”

Experiment 1: Making Iron Sulfate

Introduction: Iron sulfate can be made from the action of dilute sulfuric acid and iron. The formula for the reaction is:

Fe + H2SO4 + 7H2O => FeSO4.7H2O + H2

In other words 56 grams of Iron can react with 98 grams of sulfuric acid and some water to produce 278 grams of Iron sulfate crystals and 2 grams of hydrogen.

Please verify these numbers. As I remember the atomic weight of Iron is 56 and the molecular weight of sulfuric acid is 98. Also the molecular weight of water is 18. Please do all the calculations again to make sure that this is correct.

Actually none of this formula is needed for making Iron sulfate. (This is what makes chemistry easier than cooking!). If you use too much Iron, excess iron will remain. If you use too much acid, excess acid will remain. In both cases blue crystals of Iron sulfate will remain pure.

Procedure:

Get some scrap iron such as iron wires, iron nails or any other iron piece that you can find for your experiment. Place them in a reaction vessel. Add some water to cover all the irons and then add some sulfuric acid. Reaction starts immediately and you will see release of hydrogen from the surface of metal. Some heat can increase the speed of reaction and prevent formation of crystals on the surface of iron.

More Details:

To make Iron sulfate from scrap iron you need some sulfuric acid. You can purchase sulfuric acid from a local science supplier or laboratory supplier. You can also buy it from auto parts dealers. They know it as battery acid or battery liquid. The acid that you buy from a science supplier is usually 98% acid, but the battery acid is usually 35% acid. Some hardware stores may also carry sulfuric acid. The battery acid that you see in the right picture is packaged in flexible plastic container, enclosed in a carton box.

 

Get some scrap iron such as iron wires, iron nails or any other iron piece that you can find for your experiment. Place them in a reaction vessel. Add some water to cover all the irons and then add some sulfuric acid. Reaction starts immediately and you will see release of hydrogen from the surface of metal. Some heat can increase the speed of reaction and prevent formation of crystals on the surface of iron.

 

 

Reaction vessel can be any plastic container or heat resistant glass container. Manufacturers use large steel containers with inner coating of glass or rubber as production vessel.

As the picture shows, you can use any strong household plastic container for this reaction.

Place the iron scraps in the container and add enough water to cover the iron pieces.

 

Prepare yourself for handling acid:

Wear your protective clothing (goggles, plastic apron …) and make sure you have access to plenty of water for washing if acid spills or get to your hands or body. Small drops of strong acid can make holes on your clothing and cause burn-like blisters in your skin. You will actually feel the heat if strong acid comes in contact with your skin.

When you are ready, open the acid container and add small amount of acid to the water.

How much sulfuric acid? It depends on the concentration of the acid that you are using. If you are using 98% acid, I suggest to use one cup of acid for every 10 cups of water. In this way the concentration of your solution will be less than 20% by weight. (Density of 98% acid is almost double the density of water). For each 100 gram acid, you can expect 278 grams of iron sulfate crystals.

 

 

If you are using battery acid or 35% sulfuric acid, you may want to use one cup of acid for every two cups of water. The chemical reaction starts as soon as you add acid to the water. This reaction also produces hydrogen gas. Hydrogen is flammable, hazardous and may cause irritation in lungs. You must do the experiment in a lab, under a well ventilated hood or in an open area with sufficient air flow.

 

 

 

If you need some heat to expedite the reaction, you may place the plastic container in a hot water bath. A hot water bath can be any metal pan with hot water in that.

The process takes about 8 hours to complete in a warm environment and scraps of iron wires or sheet metals.

 

You may do titration or test the pH to determine if any acid is left in the solution; however you may visually determine the remaining acid by the color of the solution. High acid solution is blue. Low acid solution is green. No acid solution is green with yellow or brown precipitation of iron hydroxide. Both high acid and low acid solutions can be used for crystallization and yield nice crystals. I f you are using heat, continue the reaction until the release of hydrogen gas stops or yellow brown pieces appear. Then add a few drops of acid to dissolve the brown hydroxide and get a clear solution.

 

 

 

If the solution is very concentrated at this time, it will start to crystallize soon. In about 10 hours you should have your first iron sulfate crystals. If it is very dilute, you need to evaporate it. Natural evaporation takes a few days; however it yields larger crystals. Evaporation with heat is faster, but it results smaller crystals.

 

 

 

Evaporation with heat can be done in a glass beaker; however if the quality of the product is not a concern, evaporation can also be done in a steel pan, copper pan or steel pan covered by lead. When the solution is ready for crystallization, you usually see some iron sulfate drying on the sides of the container above the water level. When you stop the heat and leave the solution for crystallization, it takes about 24 hours for all crystals to form. It is best if crystallization occurs in a plastic container . Removing crystals from glass containers may be hard or dangerous.

 

 

Crystals formed in a glass beaker must be removed before they get very hard.

 

 

 

 

If you have weighted your iron scrap before and after the reaction, you know how much of the iron is used in the reaction. You can now weight the crystals to see if you have produced 278 grams of iron sulfate from each 56 grams of iron.

 

 

Need Fast Results?

Chemical reactions only happen at the surface of the metal. That is why you can increase the rate of reaction by many times if you use small iron pieces, narrow iron wire or best of all if you use iron powder. With Iron powder you may easily complete the reaction and get a solution of iron sulfate in about 30 minutes. Then all you need to do is waiting for crystals to form. Iron powder may be purchased from MiniScience.com or ChemicalStore.com.


Experiment 2: Making Iron hydroxide

Introduction: Iron hydroxide is used as a pigment, it can also be used to make other iron related chemicals. For example iron hydroxide can react with acetic acid to make iron acetate. Iron hydroxide can be made from the reaction of iron sulfate solution with sodium hydroxide solution. The formula for the reaction is:

2NaOH + FeSO4 ==> Fe(OH)2 + 2 NaSO4

Hazards: Sodium hydroxide is hazardous. Contact of Sodium hydroxide with eyes can cause permanent blindness and disfiguration. Goggles, protective clothing and rubber gloves are needed for handling sodium hydroxide.

Procedure:

  1. Weight 80 grams of sodium hydroxide.
  2. Weight 278 grams of iron sulfate crystals.
  3. Dissolve the caustic soda in about 250ml water.
  4. Dissolve the iron sulfate crystals in about 500 ml of water (warm it up if needed)
  5. Slowly mix two solutions in a larger container. The reaction creates some heat. Mix the solution while forming green iron hydroxide. Let the hydroxide to precipitate for about 24 hours.
  6. Decant the excess water from the top. Place the remaining sludge in warm place to dry.

More Details:

Sodium hydroxide can be purchased from laboratory suppliers and from hardware stores. Sodium hydroxide is also known as caustic soda and is used to open clogged drains. It may be in the form of white flakes or white granules. Dissolve sodium hydroxide in water and stir until it gets clear. Also prepare some iron sulfate solution if you don’t already have it ready.

 

 

 

Mix two liquids and stir the mixture. Iron (II) hydroxide or ferrous hydroxide will form that has a light green color.

If you already have unknown concentrations of iron sulfate and sodium hydroxide, you will not know how much of each solution to use to make iron hydroxide. In this case you can mix quantities that result a neutral pH. Sodium hydroxide increases the pH while iron sulfate reduces the pH.

 

 

 

Ferrous hydroxide is not stable, so it gradually changes to other oxides and hydroxides of iron or a mixture of them. You will see that the surface of material changes color and becomes dark green and brown.

Iron hydroxide sludge can also be separated by filter paper; however, the filtration may take a long time to complete.

 

 

The clear liquid that you separate contains sodium sulfate. If you skip filtration or do it partially, some sodium sulfate will remain in your final iron hydroxide product. This may not be important if iron oxides and hydroxides are being used as pigments.

 

 

 

 

When the sludge is separated you need to let it dry. place the sludge in a tray and place it outside do dry naturally. You may use an electric fan to speed up drying. You may also place the sludge in a warm oven for fast evaporation of excess water.

 

 

 

To dry iron hydroxide naturally in a tray, cover a tray with a plastic film and then pour the sludge over the plastic. In this way dried product will separate easily.

Large manufacturers use spray dryers or sludge dryers to dry large quantities of such material.

 

Variations: Repeat this experiment while using other alkaline chemicals instead of caustic soda. You may try potash (Potassium hydroxide), baking soda (sodium bicarbonate), soda ash (sodium carbonate) and liquid ammonia (ammonium hydroxide). Which of the above chemicals is used as laundry detergent and can be found in supermarkets?


Experiment 3: Making Iron Oxide, Red

Introduction: Iron oxide red or ferric oxide (Fe2O3), also known as rouge can be produced in various ways, including thermal decomposition of iron salts, such as ferrous sulfate.

Procedure:

  1. Leave some iron sulfate crystals in a warm space and exposed to the air current until it loses its water and changes to white powder.
  2. Place the dry powder in a crucible and heat it to about 600ºC until it changes color.

More Details:

Crucibles are usually made of ceramic, china or graphite; however in this case you can also use strong iron containers with similar results. Heat source can be a furnace or gas flame.

Materials and Equipment:

List of material can be extracted from the experiment details section. In general you will need:

  1. Sulfuric acid
  2. Iron (Iron Powder, Iron Wire or Iron pieces)
  3. Glass beaker or plastic container
  4. Funnel
  5. Filter paper (coffee filter)
  6. Caustic soda (sodium hydroxide)
  7. Crucible
  8. Heat source
  9. Goggles, apron, gloves

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.

Calculations:

Calculations are optional but very helpful. You must weight all material (if possible) and calculate the amount of each final product and its relation with the amount of material used in production. You should also be able to calculate the molecular weight of chemicals using the atomic weight of its elements.

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. Following is a sample result for experiment number 1.

As soon as I added the sulfuric acid to the iron wires already submerged in water, the reaction started and I could see the release of hydrogen gas from the surface of iron. The reaction continued for two days and I could see the green crystals formed on the iron. After two days I noticed that the reaction has come to the halt because of crystals covering the iron. At this time I started to warm-up the reaction vessel. Heat dissolved the crystals and reaction started again.

After a few hours when the reaction slowed down again I stopped the heat and removed iron pieces. I weighted the remaining iron and noticed that weight of iron reduced 104 grams. A quick calculation showed that I must get 516 grams crystals.

I left the solution for crystallization. In about 3 days I got 420 grams crystals. I separated the crystals and left the liquid portion in the vessel. This liquid portion refused to crystallize even after I used heat to evaporate excess water. Only a white powder precipitated. Testing the pH showed that this remaining liquid is very acidic.

Conclusion:

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. This is a sample conclusion for experiment 1:

Excess acid prevents crystallization of Iron sulfate. Anhydrous Iron sulfate in the form of a white powder will be formed in presence of excess acid. For best results in manufacturing Iron sulfate, presence of excess acid must be prevented.

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.

Possible Errors:

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.

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