U1A3-Investigating the properties of water PDF

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Properties of water lab...

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Sivaareni Selvakumar SBI4U1-60 Mr.Field February 8th, 2021

Investigating the properties of water Part 1 Explain the effects in terms of cohesion and surface tension In the dime and water droplet experiment, cohesion is what contained the huge water droplet together. When something is cohesive it means that the molecules are sticking together. In this case, the hydrogen bonds from the water were sticking together to create the dome-like shape before the surface tension broke and the water that was on the dime overflowed onto the paper towel. The surface tension is also what helped create the dome-like shape on the dime. The surface tension is what held the droplet together before the extra droplet that the coin couldn’t hold broke it. Surface tension is due to cohesion. In the water droplet experiment, we had to place a dime on a paper towel, then dip our finger in a glass of water, and let the water from our finger drip onto the dime. We had to continue to do this until the surface tension broke from an overflow of water on the dime. For this experiment, we had to do it twice, once on a clean dime, the second time on a dime with a thin coat of dishwasher soap. When I did this experiment on the clean dime it took me a total of 15 droplets before I broke the surface tension with the 16th drop. As for the second time with the dishwasher soap, it took me 13 droplets before I broke the surface tension with the 14th drop. As noted the clean dime took more droplets than the one with the dishwasher soap. This dish soap required fewer drops because the soap partially dissolves into the water. Dish soap actually breaks up water molecules due to the cleaning agents they have. Since the water molecules are

Sivaareni Selvakumar SBI4U1-60 Mr.Field February 8th, 2021 being broken the surface tension also breaks quicker and easier making the dime with the

dish soap require fewer droplets than the clean dime.

Part 2 Explain the difference in drop shape in terms of adhesion and hydrophobic interactions Cohesion is when the same molecules stick to each other, adhesion on the other hand is when two or more different molecules like to stick to each other. Adhesion is also what enables capillary action. In the experiment, there was a drop of water on a plate and on wax paper. When the droplet was placed onto the plate, it was more spread out and bigger compared to the drop on the wax paper. When the droplet was placed on the wax paper, the droplet was smaller and contained. Part of the reason that the droplet was more contained is because the adhesion allowed capillary action to have the droplet be taller and smaller compared to the droplet on the plate which was more spread out. The other half of the reason for the droplet being smaller and taller on the wax paper compared to the plate is due to its hydrophobic interaction. The wax paper had a chain of carbons which made the wax paper hydrophobic to the water because the carbon molecules and water molecules won’t mix. This allowed the droplet to stay in one place and not spread as easily as the droplet on the plate which didn’t have any hydrophobic interactions. In this experiment, we had to place out a plate and a sheet of wax paper. We then had to prepare a glass of water and then dip our finger into the water like the previous experiment, and we had to place a droplet of water on both the plate and the wax paper. The purpose of this experiment was to see how the shape of the droplet formed differently on each material. By looking at the

Sivaareni Selvakumar SBI4U1-60 Mr.Field February 8th, 2021 shape of the drop I was able to explain how adhesion, capillary action, and hydrophobic

interactions came into play between the water and the two different surfaces.

Part 3 What did the water do? How did the Ink change? Explain your results using the terms capillary action, adhesion, polar molecules and hydrogen bonding. During this experiment, the coffee filter absorbed the water from the cup soaking the entire coffee filter. The ink on the coffee filter changed by spreading up the coffee filter due to the water absorption from the cup. Both of the actions that resulted are due to capillary action which is enabled by adhesion. The adhesion between the coffee filter and the water allowed the coffee filter to start absorbing the water, the capillary action then allowed the water to go up the coffee filter as well as the ink to spread up the coffee filter. The water molecule is a polar molecule because of its high electronegativity that comes from the oxygen atom. The polarity of the water also affects its capillary action because the oxygen atoms partial negative charge and the hydrogen atom’s partial positive charge. In this experiment, hydrogen bonding was present in the water. The hydrogen atoms from the water molecule covalently bond to the lone pairs of electrons on the oxygen atom which results in a dipole-dipole covalent bond.

In this experiment, we had to get a cup of water, and a coffee filter with a dot of a marker on it. We then had to place the coffee filter with the marker on it into the cup of water and observe it over 15 minutes on how the colour of the marker spreads to the other end of the coffee filter from capillary action. When

Sivaareni Selvakumar SBI4U1-60 Mr.Field February 8th, 2021 I did this experiment it took me a few tries to get the marker to spread. When I finally got it, I

noticed how the marker spread out from the dot going in an upwards direction from capillary action, and I also noticed how as it went up the colour started to fade. When the 15 minutes were up, my coffee filter went from the red dot and spread out into a dull pink. I also did the experiment with a blue marker and noticed how the blue dot spread out into a dull purple.

Part 4 Explain the affect in terms of polarity, density and the role of hydrogen bonds. In this experiment, the hydrogen bonds between the water and ice were stronger than the hydrogen bonds between the alcohol and ice. The reason for this is because the Alcohol molecule is bigger than the water molecule. This affects the hydrogen bond because since ice’s molecule is small it bonds better with the water molecules which only have hydrogen and oxygen atoms, compared to the bigger alcohol molecules which contain the extra atom of carbon making it more complex to bond. Alcohol is able to bond with the ice due to its hydroxyl group. Due to the partially negative charges on the oxygen atom and the partially positive charges on the hydrogen atom, there is polarity when the hydrogen bonding occurs due to the difference in electronegativity. Alcohol is less dense than water. This is because as mentioned before, the water molecule structure is less complex than that of the alcohol’s, meaning that the water molecules are more closely packed together because the hydrogen bond is stronger, and the alcohol molecules aren’t as closely packed together because it has a weaker hydrogen bond. In this experiment, we had to fill up two cups, one with water and the other with alcohol, we then had to drop an ice cube in each cup. The purpose of this activity was to see how the ice reacts with the two different liquids. When I placed the ice cube in the water it floated, this was due to the

Sivaareni Selvakumar SBI4U1-60 Mr.Field February 8th, 2021 density of the water being high resulting in the water having a large enough mass to allow

the ice cube to float, the density being high as mentioned before is due to the hydrogen bond between the water molecules being strong. When I placed the ice cube in the alcohol it sank all the way to the bottom. This was because the alcohol had a low density which meant the mass of the alcohol (all though it had the same volume as water) was not large enough to allow the ice cube to float. This once again as mentioned before is due to the fact that alcohol’s hydrogen bonds between the alcohol molecules aren’t strong enough to stay packed together to have a large mass.

Part 5 What is physically happening when we say something is dissolved? Explain your results using the terms hydrophobic interactions, intermolecular force of attraction, and hydrogen bonding. When we say something is dissolved it means that physically you initially see two different substances but once it is dissolved you only physically see one substance because one of the substances mixes into the other, making you physically see only one substance. Oil is a hydrophobic substance, which means that oil is a nonpolar molecule. Water and sugar on the other hand are hydrophilic substances meaning that they are polar substances. Water has all three intermolecular forces of attraction resulting in it being polar. Water has London dispersions forces, dipole-dipole forces, and strong hydrogen bonding. Oil on the other hand only has London dispersion forces and no hydrogen bonds making it nonpolar.

Sivaareni Selvakumar SBI4U1-60 Mr.Field February 8th, 2021 In this experiment, we had to get two cups, one filled with water and the other filled

with oil. We then had to continue to put a teaspoon of sugar into each liquid until it stopped dissolving. The purpose of this experiment was to see how much sugar each substance can dissolve until it reached its saturation point. For the water, I was able to dissolve 10 teaspoons of sugar before

it hit its saturation point. The water was able to dissolve that many teaspoons of sugar because both the sugar and the water are polar hydrophilic substances. The oil on the other hand wasn’t able to dissolve a single teaspoon of sugar. This was because oil is a hydrophobic nonpolar substance while sugar is a hydrophilic polar substance. Since oil is hydrophobic it means it is not a solvent making the sugar undissolvable.

From doing this lab I’ve learned and come to a great understanding of the different properties of water. This lab has helped me describe different terms from my own full understanding. I was able to compare the properties of water to other substances, and learn how water has stronger hydrogen bonds compared to other substances. I was also able to determine whether something was hydrophilic or hydrophobic, or whether it was cohesive or adhesive based on the reactions that occurred while experimenting. This experiment was a great way for me to build my knowledge on different the terms of the properties of water.

Sivaareni Selvakumar SBI4U1-60 Mr.Field February 8th, 2021

References Cohesion and adhesion of water (article). Cohesion and Adhesion of water. https://www.khanacademy.org/science/ap-biology/chemistry-of-life/structure-of-water-and-h ydrogen-bonding/a/cohesion-and-adhesion-in-water.

Arnett, M. (2018, July 19). Does It Sink or Float? Depends on the Soap! Scientific American. https://www.scientificamerican.com/article/does-it-sink-or-float-depends-on-the-soap/.

Than, J. (2020, August 15). Hydrophobic Interactions. Chemistry LibreTexts. https://chem.libretexts.org/Bookshelves/Physical_and_Theoretical_Chemistry_Textbook_M aps/Supplemental_Modules_(Physical_and_Theoretical_Chemistry)/Physical_Properties_of _Matter/Atomic_and_Molecular_Properties/Intermolecular_Forces/Hydrophobic_Interaction s.

Sivaareni Selvakumar SBI4U1-60 Mr.Field February 8th, 2021 Hydrogen Bonding.

https://www.chem.purdue.edu/gchelp/liquids/hbond.html#:~:text=Hydrogen%20bonding%20 is%20a%20special,and%20another%20very%20electronegative%20atom....