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Testing for Vitamin C with Iodine – Free Lesson Printables

On this experiment, we’ll check for vitamin C with iodine. Now we have performed this experiment a number of instances, repeated some liquids, and added new ones with every check.

A number of the juices we used included contemporary lemon juice, Emergen-C® vitamin drink combine, store-bought orange juice, selfmade pumpkin, acorn squash, and cranberry “juices.”testing for vitamin c with idodine

Does pumpkin comprise Vitamin C?  How about lemon juice? Does freshly squeezed lemon juice comprise the next focus of vitamin C than bottled lemon juice?  Let’s discover out!

A phrase of recommendation! Don’t simply check pumpkin. Additionally, check contemporary or bottled lemon juice and orange juice alongside the pumpkin so your kids can perceive the totally different degree of Vitamin C focus in numerous meals.

Word: A variety of ages can full this exercise. Now we have added extra superior vocabulary and ideas for older college students. The method and chemical reactions are fascinating for all ages.

As you check for vitamin C, use the worksheets we’ve ready as they apply to your kids and their comprehension degree. In different phrases, please don’t NOT do that experiment due to the extra superior explanations used on this intro and the “what occurred” part of this publish.

Why Check for Vitamin C with Iodine?

Vitamin C is ascorbic acid. A molecule of ascorbic acid is depicted beneath. Understanding how nutritional vitamins, proteins, and different essential natural compounds are important to our our bodies will assist our kids make smart, health-conscious choices. If you’re doing a human physique, diet, well being, or animal science examine, this experiment will relate properly to any discussions on nutritional vitamins, minerals, and dietary decisions.

Testing for vitamin c with iodine vitamin c molecule

Ascorbic Acid Molecule


What are Nutritional vitamins?

Nutritional vitamins are small natural compounds that each one dwelling organisms must survive – even microbes. Nutritional vitamins are sometimes damaged into two classes: fat-soluble and water-soluble. These classifications can inform us lots in regards to the chemical composition of those nutritional vitamins (equivalent to whether or not they’re polar or nonpolar), together with indicating how shortly the nutritional vitamins are used within the physique. Fats-soluble nutritional vitamins (A, D, E, and Okay) are saved within the fats of organisms to last more, and the physique releases them as wanted. Water soluble nutritional vitamins (C and all B-complex nutritional vitamins) are shortly used within the physique and launched with the passing of urine.

However What Makes Vitamin C So Essential?

Whereas people have sturdy programs able to producing many vitamins and nutritional vitamins, we can not create ascorbic acid for our personal use, so we should take vitamin C dietary supplements or ingest vitamin C by way of food and drinks.

Testing for vitamin C with iodine photo of cells
Within the human physique, vitamin C is essential for the restore of tissues, strengthening of bones, immune system assist, and the absorption of iron by the physique. Vitamin C acts as an antioxidant, which aids within the prevention of most cancers by neutralizing free radicals.

What are free radicals?

Atoms have three essential parts: protons, electrons, and neutrons. The protons and neutrons make up the nucleus of the atom. The electrons orbit across the nucleus in what is named power shells. Every power shell has a sure variety of electrons it must be full. The primary shell can solely maintain 2 electrons, and every subsequent shell can maintain as much as 8. The variety of electrons naturally present in every atom is named their valence electrons. For instance, the primary shell of carbon is full with 2 electrons. Carbon solely has 4 electrons in its secondary shell. This implies carbon has a valence of 4 and might make 4 bonds with different atoms.

Free radicals are atoms, ions, or molecules which have develop into unstable as a result of having a number of unpaired valence electrons of their outer power shell. Due to their unstable nature, they’ll start to try to bond with steady electrons, which in flip causes them to develop into unstable. The instability causes a cascade of antagonistic results. On the finish of this publish, we hyperlink to sources explaining the results of free radicals on our our bodies.

How do antioxidants assist struggle free radicals?

Antioxidants, like vitamin C, have an additional electron. As such, they can bond to these free radicals, inflicting them to develop into steady as soon as once more. Generally, antioxidants will utterly undo the free radical molecules.

Nonetheless, having too many antioxidants could be detrimental. If you’re curious in regards to the science behind this, comply with the hyperlinks on the finish of this publish.

On this exercise, your pupil will use a laboratory method referred to as titration. When performing a titration, college students will rigorously add one drop at a time of 1 resolution into one other resolution, stir, and observe for a colour change. The drops required to achieve the colour change are recorded.

We’re going to use a starch-iodine resolution as our indicator. We are going to then add our totally different juices, one drop at a time, and observe the colour change.

In our experiment, we’ll add juice drops into the starch-iodine indicator till the combination is colorless.

There’s extremely correct testing tools in skilled labs. However, we’ll undergo the method as precisely as attainable in our dwelling laboratories!

Essential: Iodine use comes with security warnings. You may learn and share this together with your pupil. Here’s a lab security sheet on iodine. Please have security glasses accessible earlier than your kids begin testing for vitamin C with iodine.

Word: We did this experiment twice. The primary time we examined for vitamin C, we used EmergenC®, contemporary lemon juice, acorn squash “juice,” and cranberry “juice.” The second time we used pumpkin “juice”, fresh-squeezed lemon juice, and EmergenC®.

Getting ready to do Some Testing for Vitamin C with Iodine

We talked in regards to the experiment forward of time and mentioned what liquids we needed to check. We chosen Emergen-C®, freshly-squeezed lemon juice (versus bottled lemon juice), acorn squash juice, pumpkin juice, and cranberry juice.

You should use bottled juice; you don’t must make your personal from the contemporary greens or fruit. Use what works for the setting you’re in and the group of scholars you’ve gotten finishing this exercise.

Your check MIGHT contain testing fresh-squeezed lemon juice vs. bottled lemon juice. Or, you may check EmergenC® with bottled orange juice. Or, you may check various kinds of vinegar and bottled lemon juice. There are numerous combos.

Focus on together with your kids what liquids they wish to check for vitamin C. Then, have them analysis the quantity of vitamin C in a juice pattern. Use the information sheet in our printable packet created for this experiment.

Obtain the free printable for this experiment. You’ll be added to our electronic mail neighborhood. We promise to not spam you! If the field beneath doesn’t assist you to sort within the packing containers, please examine for pop-up blockers in your browser. Additionally, don’t embrace empty areas firstly and finish.

testing for vitamin c with iodine downlad the printables


As you proceed by way of the experiment, your kids can then fill within the the rest of the information sheet and examine the outcomes with the quantity of vitamin C in a serving of the juice.

Testing for Vitamin C with Iodine – Step 1: Making “Juice”

Since we had been testing liquids, we needed to make our juice for the acorn squash, contemporary cranberries, and contemporary pumpkin. It’s essential to notice that you simply don’t put together the vitamin C samples too far prematurely (as in a number of hours) as ascorbic acid can oxidize over time, given the publicity to oxygen within the air round us.

Please be aware that the juice we made with the chopped cranberries had a deep reddish tint to it. After we added it to the indicator, it turned extra purple, however did loosen up some over time. This, in itself, was a lesson for us. So, even when your kids wish to strive one thing like bottled grape juice or balsamic vinegar, it would lead to some fascinating observations and discussions.

For this reason I really feel it’s essential to your pupil to finish the pre-experiment analysis type in our printable pack. They’ll take a look at the per serving quantity of vitamin C and the outcomes of the titration.

Testing for vitamin c with iodine supplies

  • Lower up the pumpkin and grind it (pulp and all) till  there’s about 1cup of chopped pumpkin. We did the identical for the acorn squash and the cranberries. Place the pulp from every is in its respective bowl.

Testing for Vitamin C with Iodine Extracting Juice from a Pumpkin


  • To every bowl of ground-up materials, add 1/4 cup of distilled water. If there’s not a small quantity water on the backside of the bowl, add 1 Tablespoon extra, stir, examine to see you probably have any liquid on the backside. You don’t wish to dilute the pure juice popping out of the pumpkin, acorn squash, or cranberry an excessive amount of. You simply wish to be sure you have some liquid. Stir every combination properly.
  • Set this apart for about 15-20 minutes.
  • Use cheesecloth or a espresso filter to pressure every combination. We strained every juice into its flask or bowl. You should definitely hold the whole lot separate. Use separate items of cheesecloth or espresso filters. If stirring or scraping a combination out of a bowl, use totally different utensils between mixtures.

  • You’ll find yourself with a number of containers of juice. It could be useful to label every, if among the liquids have a really related colour.

testing vitamin c with iodine - liquids to test

Testing for Vitamin C with Iodine – Making the Starch-Iodine Indicator

 For this portion of the experiment, you will have:

  • Distilled water
  • Measuring cup or beaker
  • Glass stir sticks or a number of clear spoons for stirring
  • Cornstarch
  • The liquids you’re testing
  • Distilled water
  • Saucepan
  • Warmth supply
  • Check tubes and check tube rack. You might do that utilizing glass bowls or beakers too. Adapt for what you’ve gotten. Since we do chemistry actions with younger kids too, we use these plastic check tubes.


  • Placed on security glasses and gloves. Iodine use comes with security warnings. You may learn and share this together with your pupil. Here’s a lab security sheet on iodine.
  • In a glass container that may maintain 12 ounces, add 2 tablespoons of cornstarch with simply sufficient distilled water to make a paste. (If you must add extra water and cornstarch to get the paste finally, that’s okay. We had to try this too. We added 1 tablespoon at a time and little extra water till we had a paste!

  • Measure 8 ounces or 250 mL of distilled water and blend it into the cornstarch paste.

testing for vitamin c mix cornstarch and distilled water

  • Stir properly, then pour right into a pan and produce to a boil. Stir continuously.
  • Whereas ready for the indicator to boil, have one other individual arrange the check tubes or mixing containers you intend to make use of. Arrange the liquids/juices you’ll be testing. Have the glass stir sticks or spoons prepared too. When you have check tubes however don’t have the glass stirrers, you may swirl the check tube after every addition of drops.

testing for vitamin c with iodine set up test tubes

  • When the starch and water combination reaches boiling, take away it from the warmth.
  • Subsequent, pour 4 ounces of this indicator resolution right into a glass bowl, flask, or measuring cup. (Watch out as a result of it’s nonetheless very popular!)
  • Add sufficient drops of the iodine to show the 4 ounces of indicator a darkish blue, nearly black. Stir properly. This resolution is the ultimate starch and iodine indicator.

Testing for Vitamin C with Iodine – The Huge Check!

Beneath are the procedures for testing for the presence of vitamin C with iodine.

A Assessment of Impartial and Dependent Variables Earlier than We Get Began

If you’re solely testing pumpkin (for instance small pie pumpkins vs. massive carving pumpkins) focus on together with your kids, co-op, or class the variations listed within the Taking It Additional part, chances are you’ll wish to check one of many impartial variables listed: sort of pumpkin, how a lot the pumpkin is chopped up when extracting the juice, and so on.

Ask your college students as you begin this process:

  • What’s the impartial variable? The impartial variable is the variable we manipulate or change. On this experiment, as we accomplished it, the kind of juice was our impartial variable. We may change that and solely use pumpkin, however check various kinds of pumpkin; for instance, we may check pie pumpkins vs. massive carving pumpkins. Nonetheless, we’d like to ensure all steps are accomplished precisely the identical (the identical quantity of chopping, the identical quantity of water added to the chopped pumpkin, and so on.). The one variable that ought to change is the one chosen impartial variable.
  • What’s the dependent variable? The dependent variable is what we measure. On this experiment we’re measuring the variety of drops put into the starch-iodine indicator till it reaches a colorless look and titration ends.
  • Remind your college students that the perfect experiments check one impartial variable at a time so we will observe the trigger and impact relationship between the impartial and dependent variables extra successfully.

You will want:

  • Pipettes or droppers – 1 for every liquid you’re testing
  • Check tubes and rack or small glass bowls
  • Pencil and our useful recording sheet (Request it beneath.)
  • The cornstarch-iodine indicator
  • Glass stir stick or spoons
  • Non-compulsory: You may wish to prep a small label with the title of every liquid and place it by the suitable check tube or container the place you’ll be conducting the titrations.
  • Measure 5 mL of the starch-iodine indicator and pour it into every check tube.

  • Have the recording sheet and pencil useful. You may request our measuring sheet beneath.
  • Utilizing a clear pipette, start dropping the primary juice to be examined into the primary check tube or no matter mixing container you’re utilizing. Dispense one drop at a time. Stir in between drops. For those who wouldn’t have glass stir sticks, shake the check tube. When the liquid is colorless, document the variety of drops distributed to that time. That is the tip of the titration.

  • Word: After we examined the EmergenC™, the indicator went colorless after six drops. The lemon juice took 21 drops, and the pumpkin, cranberries, and acorn squash took anyplace from 64 to 170 drops! Your outcomes will fluctuate, so no worries if it takes way more juice than anticipated to show the indicator colorless. Keep in mind, one thing just like the darkish orange pumpkin juice, with much less viatmin C than the EmergenC™ goes to take extra drops till titration ends. Our pumpkin juice is within the far check tube to the left within the picture beneath. It did loosen up, however by no means acquired completely clear. Your outcomes shall be totally different.
  • Transfer on to the following liquid to be titrated. Repeat till completed. Within the picture beneath, the check tube on the left (our pumpkin juice) began out a darker orange. After 170 drops, this was the colour. So, we stopped including at that time.We concluded it did have some vitamin C, however the colour of the beginning liquid could have precluded it turning completely colorless. Plus, we knew this vegetable had a lot much less vitamin C than the lemon juice and EmergenC™. Your pumpkin juice will most probably carry out in another way. We used a small baking pumpkin.

  • Use the dialogue questions to assist your youngster talk their findings.


Testing for Vitamin C with Iodine:  What Occurred and Dialogue Questions

When iodine is launched into a combination excessive in vitamin C, the ascorbic acid turns into oxidized. The hydrogen atoms present in ascorbic acid will mix with iodine to type iodide ions. This chemical response creates a colorless impact in liquids excessive in vitamin C.

After we examined our cranberry “juice,” it was tough to inform when the titration ended due to the purple colour of the extracted juice. In your prep for this experiment, chances are you’ll wish to embrace a darker juice and ask your pupil what they assume will occur. 

So, what precisely is occurring on this experiment?

Throughout titration, a chemical response takes place, and a course of referred to as an oxidation-reduction response happens. The oxidation-reduction response can also be known as redox.

 In an oxidation-reduction response, one substance within the response loses electrons (oxidation), and the opposite substance features electrons (discount). Discount could sound counterintuitive, however discount refers back to the discount of the receiving atom’s optimistic cost by gaining an additional negatively charged electron.

On this experiment, the vitamin C within the juices examined is oxidized (as a result of it loses electrons), and the iodine is lowered (as a result of it features electrons.)

Extra About Titration

The titration course of ends on this chemical response when the indicator is colorless. To find out the endpoint of the titration as precisely as attainable, add one drop at a time, and stir or swirl the check tube after every addition. The titration is full when the indicator is colorless (or reaches the specified colour or lacks colour).

On this experiment, the iodine resolution is the titrant, the substance which is added to throughout titration. The liquids (lemon juice, acorn juice, cranberry juice) used are known as the analyte, the substance whose chemical make-up is analyzed and decided through titration.

Remind your pupil that atoms are by no means destroyed or created in a chemical response. In a chemical response, atoms are rearranged. The vitamin c molecule misplaced electrons on this experiment, and the iodine gained electrons.


Testing for Vitamin C with Iodine – Dialogue

Please be aware the next is included in our printable. Request the printable utilizing the sign-up field beneath.

  • Which liquid turned the indicator colorless with the least variety of drops? What does this imply?
  • Which liquid took essentially the most drops to show the iodine colorless? Did the entire indicators flip colorless?
  • Wanting on the quantity of vitamin C per serving that you simply recorded in your lab worksheets, did the outcomes of this experiment match the per serving info?

Taking This Additional

As talked about above, our pumpkin juice had over 170 drops and nonetheless was mild orange. We used a baking pumpkin, what may we do if we repeated this titration with pumpkin?

  • Change the dimensions of the pumpkin? (A small pie pumpkin vs. a big carving pumpkin.)
  • A white pumpkin vs. an orange pumpkin
  • Put much less of the “guts” and extra of the skin pores and skin of the pumpkin?
  • Grind it to a really skinny pulp to extract extra liquid and run the titration with out ready 15-20 minutes after chopping the pumpkin (to assist scale back the possibility of oxidation)?
  • For those who’re doing this as a bunch, you might have every group change a special variable listed right here.

Obtain the free printable for this experiment. You’ll be added to our electronic mail neighborhood. We promise to not spam you! If the field beneath doesn’t assist you to sort within the packing containers, please examine for pop-up blockers in your browser. Additionally, don’t embrace empty areas firstly and finish.

testing for vitamin c with iodine downlad the printables

Different Useful Assets

Extract DNA from a Pumpkin

Huge record of chemistry actions

Pumpkin STEM & Science Actions

The Advantages of Vitamin C and Why Your Baby Wants it – The Cleveland Clinic

Vitamin C: Meals, Capabilities, How A lot Do You Want, and Extra – from the European Union Meals Data Council

Free Radicals Data from the Nationwide Library of Medication – The Summary part of this examine offers a concise clarification.

Understanding Anti-oxidants from Harvard Well being






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