Water report

Introduction: We are studying biology, which is the study of life. All life needs water to survive, which is why studying it is important. This lab will focus on the properties of this vital substance and compare it to others like it. The three parts of the lab will discuss water’s specific heat, the surface tensions of three different substances, and water as a solvent.

Problem: A) If you heat both alcohol and water at the same temperature and for the same amount of time, which will have a higher temperature at the conclusion of the experiment? Which will cool down more quickly?

B1) Which liquid has more surface tension: water, alcohol, or soapy water? If you drip any of these three substances on a penny, which will roll off faster (be able to hold least long drip-wise on the penny without spilling off the side)?

B2) Does water’s surface tension decrease if you add soapy water to the substance?

C) Will temperature have an effect on how much salt you can dissolve in water?

Hypothesis: A) I think that Alcohol will heat up faster than water, because alcohol is lighter in weight, so there is less matter to apply energy to, so it takes less time to complete any task that requires the use of energy on that substance.

B1) I think that soap will have the most drops stay on the penny, water second-most and alcohol the least.

B2) I think that the best way is to fill up the container to the top and then push the paperclip in from the side. Then, when I add soap, the paperclip will fall to the bottom because of decreased surface tension.

C) I do not think that temperature will have an effect on water’s solubility at all.

Data: A)

Data Table	Water	Alcohol
Temp. before heating	30°C	28°C
Temp. after heating	93°C	81°C
Temp. after cooling

B1)

	Water	Alcohol	Soapy Water
Estimated # of drops	6	4	8
Actual # of drops	36	28	15
Observations	Much greater than anticipated, greatest # of drops.	Much greater than anticipated, second -greatest # of drops.	Much greater than anticipated, least amount of drops.

B2) N/A

C)

	Hot Water	Cold Water
Temperature of Water	90°C	6°C
Grams of salt dissolved	20	7.5
Observations	The amount of salt that could be dissolved in hot water is definitely greater than that of cold water.

Conclusion: A) 1) Specific heat is the amount of heat per unit mass required to raise the temperature by one degree Celsius.

2) Water has a higher specific heat, because it takes more heat to raise its temperature that it does to raise the temperature of alcohol.

3) Your body is about 75% water, and if water had a low specific heat, then you would boil to death on relatively cool days. Also, if water had a really low specific heat, you wouldn’t be able to cool down card fast enough.

B1) 1) My estimate was way off the actual amount of drops that stayed on the penny for each and every substance. I did not realize how big a penny was compared to the size of the water drops.

2) The difference between water and soapy water was that water stayed longest of all, and soap stayed least of all, totaling the difference to 16 drops. I think this happened because soap drastically decreases the surface tension of water.

3) Cohesion – When elements or molecules are attracted to each other in one way or another. This influenced my results because the molecular attraction between the molecules of each substance was different, so each was able to stay on the penny for different lengths of time. Surface tension – when the surface molecules’ cohesive forces aren’t balanced, the surface contracts, making it look like an elastic membrane. This affected my experiment, because without surface tension the water would not be able to make that dome shape and would have to stay flat, so not even one drop could stay on the penny.

B2) 1) I carefully placed the paperclip on the side of the cup so that one side was in the water, the heavier side, then I slid the rest of it in.

2) When I added soap, the paperclip sunk to the bottom of the bowl, because soap decreases the surface tension of water.

3) Hydrophilic substances are those that love water and want to bond with it (ewwww), and hydrophobic substances are those that are scared to death of water and would do anything to get away from it.

C) 1) I dissolved much more salt in hot water than in cold, which surprised me very much. The difference was an entire 12.5 grams! I think this may be because hot water’s molecules move around more, so they need more room to move around (some of which they don’t use), so there is more room for solutes. Then again, I am only hypothesizing – I’m not sure of why this truly happens.

2) A solute dissolves in a solvent through polar bonds – where one molecule is weakly attracted to another through negative or positive charges. I don’t know what role temperature plays in this.

3) I think more salt could dissolve in water, because olive oil has larger molecules, and thus one molecule fills up more space. If so, and there is one salt molecule per oil molecule, then the oil would dissolve less than water.