The Effect of Chemical Ratio on the Tensile Strength of Alginate Strings By Kate Doorn and Gauge Anderson Whitefish High School Advanced Chemistry - Mr. Spangler Purpose: We will be testing different ratios of the chemicals (calcium chloride and sodium alginate) to see which ratio results in the strings with the highest tensile strength. Hypothesis: As the concentration of sodium alginate increses the tensile strength of the sodium alginate/calcium chloride strings will also increase. Reaction Occurring: When sodium alginate comes into contact with calcium ions the calcium ions replace the sodium ions in the polymer. Because each calcium can attach to two polymer strands it is considered to be a cross linking polymer. Procedure: To make strings we used the process of direct spherification, which means we introduced sodium alginate solution into a calcium chloride bath. To make strings of uniform thickness, we rigged a syringe containing the alginate solution to a ring stand so that it was suspended over a spinning bath of calcium chloride. We then placed a weight onto the plunger of the syringe and the solution entered the spinning bath making strings. These strings tensile strength was then tested by using a spring scale by taking 4 inch lengths of string, folding them over the scale and pulling until they snap. We initially tested a 0.8% sodium alginate solution to a 1% calcium chloride bath, then we repeated the process with a 0.4% alginate solution. Our plan is to continue to change the concentrations until we find an ideal ratio. Round 1 Tests: Breaking Strength Improvements: We could improve our testing method by slow motion videoing our tensile tests. We currently are just using a spring scale and watching when the string breaks but with a slow motion video we could get more precise measurements of the strength. Results: So far we have found that both concentrations of the strings were stronger after being dried for 20 minutes and the the higher concentration (0.8% sodium alginate) was stronger. Where We Are Going: We plan to do more tests to determine the chemical concentrations that creates the strongest strings. To do this we will do several more tests with higher concentrations of sodium alginate and we will also try altering the calcium chloride concentrations. References: ● Moe, Størker, Gudmund Skjåk-Bræk, Olav Smidsrød, and Hisao Ichijo. "Calcium Alginate Gel Fibers: Influence of Alginate Source and Gel Structure on Fiber Strength." Journal of Applied Polymer Science J. Appl. Polym. Sci (1994): Web. ●"Cross-linking Polymers – Alginate Worms- Learn Chemistry." Cross-linking Polymers – Alginate Worms- Learn Chemistry. N.p., n.d. Web. 04 Mar ●Lee, P., and M.a. Rogers. "Effect of Calcium Source and Exposure-time on Basic Caviar Spherification Using Sodium Alginate." International Journal of Gastronomy and Food Science 1.2 (2012): Web. ●Lersch, Martin. "Texture – A Hydrocolloid Recipe Collection - Khymos." PDF Drive. N.p., Dec Web. 04 Mar TEST:1:2:3:4:5:6:Average: 0.8% Strings (wet) 75g 125g80g85g110g92g 0.8% Strings (dry) 150g170g100g140g150g100g135g 0.4% Strings (wet) 55g65g60g80g50g75g64.2g 0.4% Strings (dry) 115g105g110g120g105g115g111.7g Abstract: The polymer created when sodium alginate comes into contact with calcium ions has many modern day applications. Work has been done by scientists around the world with this process and these polymers have led to more effective wound dressings, biodegradable water bottles, and much more. We have been researching how to create the strongest alginate polymer possible using the chemicals sodium alginate and calcium chloride. We have developed a way to create strings of a uniform thickness by placing a beaker of calcium chloride on a magnetic plate, putting a magnet in this beaker, and then spinning it. We then filled a syringe with the sodium alginate solution and connected it to a ring stand with the tip about 2 cm above the calcium chloride bath. Then we put a 1 kg weight on the top of the syringe so the alginate hit the calcium chloride at a steady rate. We then left the strings in the calcium chloride bath over night so they could become solid all the way through. To test their strength we have been using a spring scale and have been folding the string over and pulling until it breaks, we then repeated this same process after the strings have dried for 20 minutes. They become much stronger once they have had time to dry. So far we have tested.8% sodium alginate: 1% calcium chloride and.4% sodium alginate: 1% calcium chloride. The.8% solution is more strong on average. Background: ●Inspiration to pursue spherification ○Imperial Sphericator ○Oohoo