The Discussion of this experiment began with discussing how many materials we use today are actually mixtures of pure substances. The separation of these materials into their pure substances can be quite challenging. When we are discussing separations of a mixture that contains pure substances, it all depends on whether you can separate the substances by physical means. That means, utilizing each substances physical properties such as boiling point, melting point, and magnetism.
Separation of a Mixture of Solids
Lab Report Assistant To begin this experiment I got out me scale and little plastic dish and the mixture of substances. I weighed the dish separate and found it to weigh 0.5g. Next I added the mixture to my dish and found the combined weight of the dish and the mixture was 5.5g. I next cut a square sheet of paper and weighed it to find it weighed 1g. I emptied the contents of my dish onto another sheet of paper in a very thin layer. I wrapped the magnet in a sandwich bag and ran it over the mixture to separate the iron. I then carefully pulled the magnet away from the sandwich bag and let the iron fall onto the square piece of paper. I repeated this 3 times to ensure I had all of the iron from my sample. I then weighed the square piece of paper and iron shavings and got a weight of 2.2g. I discarded the iron and moved the remaining mixture into the glass beaker. I added 50mL of distilled water to the mixture.
I then lit my burner and moved the stand over the flame and set the beaker with the mixture over the flame. I stirred the mixture several time and when I began to see small bubbles forming I poured the liquid into a paper cup. I then added 20mL of distilled water back into the beaker with the now sand and repeated setting it over the flame until a near boil. I then added this water to the other water in the paper cup and set the sand in the beaker over the flame to dry. I then placed the liquid that was in the paper cup into an awaiting ice bath. The ice bath would cause the benzoic acid to form crystals. I waited until the sand was room temp and felt completely dry and added it to my original dish that weighed 0.5g and found the combined total of sand and dish weighed 1.9g. I next weighed a paper cup and found the weight to be 1.7g; I also weighed the provided paper funnel and found the weight to be 0.7g.
I lined the plastic funnel with the paper funnel and poured the contents into the paper funnel to filter the now formed benzoic crystals from the salty water. I scooped out all the crystals I could see. I then added 5 mL of cool distilled water slowly into the funnel to remove and sodium chloride. I allowed it to drain for a least 30 minutes until I no longer saw any drips from the funnel into the paper cup. I then set both the salty water and the benzoic acid crystals in the paper funnel in a sunny window for 5 days to allow for evaporation of the liquid. The weight of the dried benzoic crystals and the paper funnel were 2.2. The weight of the sodium chloride and the paper cup were 2.4g. So collectively recovered 1.2g of Iron filings, 1.4g of Sand, 0.4g of Table salt, and 1.5g and Benzoic Acid. That totals 4.5g and my original total was 5g. I recorded all my data and cleaned my supplies.
Substance How to separate them
Iron Filings Use a Magnet and drag over the mixture
Sand Filter it with filter paper
Benzoic acid Heat it in water, and reaction will cause a solid to form that can be strained Salt Once everything else is removed wait on evaporation to take the water and leave the salt Data
Results are skewed because 1) I saw some Benzoic Acid crystals in my salty water that I was unable to get out, and 2) I could not get every crystal out of the first paper cup as I was transferring the Benzoic acid crystals and salt water to the funnel. Plus I started with 5g and ended with 4.5. Besides these 2 spots in the experiment, I am unsure where I could have lost some samples.
How did your proposed Procedures or flow charts at the beginning of this experiment compare to the actual Procedures of this lab exercise? I was correct with the Iron and Salt. However, the sand I was wrong and the Benzoic acid, I was partially right. I knew the Benzoic acid would need to undergo a physical change to get separated, I just didn’t know how it would occur. The sane I thought of a filter of some kind, I didn’t think of it just being heaver and pouring the liquid off and drying it. Discuss potential advantages or disadvantages of your proposed Procedure compared to the one actually used. Advantage of a filter for the sand might have saved more of the salt and benzoic acid from possible loss to the environment as it was heated and from it staying in the wet sand.
However, finding a filter that could allow sand and not salt and benzoic acid might be difficult to find. How would you explain a sand recovery percentage that is higher than the original sand percentage? The sand remained wet and yielded a false result. The water would make it weigh more, therefor giving you a higher percentage. What were potential sources of error in this experiment?
That some benzoic acid crystals made it through the filter into the salty water. Also, when transferring the Benzoic acid crystals and water into the filter you are unable to get 100% of the mixture out of the cup.