3. Trials
Amount of Salt (±0.05 g)
dissolved in 100ml of wa
Trial one: rise of water Trial two: rise of water Trial three: rise of
ter (±17.5 ml)
level (±0.2 cm) level (±0.2 cm) water level (±0.2 cm)
0.0 2.4 2.9 2.5
3.0 2.4 2.9 2.3
6.0 2.5 2.4 2.6
9.0 2.1 2.6 2
12.0 2.5 2.6 2.7
15.0 1.7 1.7 1.6
18.0 1.7 1.6 1.5
Notas del editor
Hello everyone, I am Kevin Xiao, Jerry Chang, Lois Seo and Kate Kim from group 8. Today we will be introducing our G4 experiment.“what is the effect of increasing salinity on the rate of capillary action for water?”
The independent variable of our experiment is the concentration of salt, specifically (0g/ml, 0.03 g/ml, 0.06 g/ml, 0.09 g/ml, 0.12 g/ml, 0.15 g/ml, 0.18 g/ml). The dependent variable was the height that water climbed up the strips of paper towels in centimeters. The control variables include: the type of paper towels, which were the ones available at school, the size of the paper towel strips which was 20 cm by 3 cm, amount of water in each beaker which was 200 ml and the time left for the water to climb up the paper towel strips, which was 2 minutes.The procedure of this experiment comes down to the following: We measured the height rise of water from the end of the paper towels after we left the tissue papers touching the water at the same depth, as shown in the first picture on the slide. In each case, we measured the height rise of water for 2 minutes and mixed 0g, 3g, 6g, 9g, 12g, 15g and 18g of salt for each beaker with 100 ml of distilled water in order to create varying concentrations. We conducted 3 trials in total for each concentration to increase precision and accuracy.
This graph shows the average length of soaked paper towel against the amount of salt used, which can be used to represent the rate of capillary action against the amount of salt dissolved in the solution.From here we extract a graph that shows the rate of capillary action against the amount of salt used.According to the experimental results, there is a decreasing trend in the rate of capillary action as the salinity increases.This result implies three scenarios; the intermolecular attraction between water molecules has increased, the attraction between the paper towel and the water molecules has decreased, or the density of the solution has increased. The first scenario is unlikely because the opposite can be inferred to have happened. When salt dissolves in water, it interferes with the intermolecular attraction between water molecules, as seen by the lower melting point of salt water, thus increasing the rate of capillary action.The second scenario is plausible, as dissolved salt would disrupt the attraction between water molecules and the paper towel, similar to how salt disrupts intermolecular attractions between water molecules, thus decreasing the rate of capillary action.The third scenario most certainly applies, as adding salt to a solution of water increases the solution’s density, which would reduce the rate of capillary action.
Conclusion:Thus in conclusion, increasing salinity decreases the molecular adhesion between water and the paper towel, and increases the density of the water solution, thus resulting in the decreased rate of capillary action. Limitations & ImprovementsThere are some limitations in the design of the lab. Since our goal was to measure the rate of the capillary action of water, we set a time limit. However, our time limit to 2 minutes was too long. Since the time limit was too long, water would have reached its limit for some paper pieces, so we might have measured not the rate but the amount of water that went up the towels. Moreover, the rate is not linear, so accurate measurement of rate is not possible. To improve this error, we must use shorter time limit next time, for example 20 seconds. Furthermore, there was no huge difference between the rates of capillary action of water with different concentrations of salt partly due to the little difference between the amounts of salt we put into water. We couldn’t make the difference between the concentrations big because we could put only up to 18g of salt into the water since when we put more than 18g of salt the water became saturated and the salts were not completely dissolved. We can improve this by using more amount of water, more than 200ml next time. Then water will be saturated by bigger amount of salt and therefore we can make the difference between the salt concentrations bigger and thus we will get results that are clearer to make a conclusion.
