The independent variable in the experiment is the soap and the dependent variable in the experiment is the number of water drops on the surface of the penny. The control is the penny without soap.
What property of water allows the water to stick to the penny?
The attraction of water molecules to other substances, like soil or glass, is called adhesion. As drops of water are added onto a penny, the adhesive force between the water and the penny keeps the water from falling off.
Which of the following is the dependent variable in the surface tension experiment?
A dependent variable is what is being measured in the experiment. The number of droplets is the dependent variable because it is what is being measured in the experiment. For this project, I will be testing how the surface tension of water causes the molecules of water to cling together through cohesion.
What were the results of the penny experiment?
REA . Conclusion: Use your data to answer your experimental question. The results indicate that when you drop water on a penny that the heads side of the penny will hold more drops (heads 23 drops, tails 18 drops).What did you observe when you dropped water onto the coin?
Water’s cohesion and surface tension are special because of hydrogen bonds. … The cohesion and surface tension of water becomes apparent when the drops of water you add to the penny reach the penny’s edge. Once the water has reached the edge, you begin to see a bubble or dome of water forming on top of the penny.
How many drops can a penny hold?
Were you surprised to discover that a lot more drops of water fit on a penny than you predicted? We had 27 drops of water on ours! Surface tension and cohesion is the reason you can get so many drops of water on a penny. Cohesion is the “stickiness” of like molecules to one another.
What does adhesion and cohesion mean?
Cohesion: Water is attracted to water. Adhesion: Water is attracted to other substances. Adhesion and cohesion are water properties that affect every water molecule on Earth and also the interaction of water molecules with molecules of other substances.
What controlled variable?
A control variable is an element that is not changed throughout an experiment, because its unchanging state allows the relationship between the other variables being tested to be better understood.What is the purpose of this control?
A control group allows a scientist to compare it to the other group or groups in an experiment. If a scientist notices a significant difference between the control group and one or more of the other groups, he can logically lead to the conclusion that the independent variable has an impact on the dependent variable.
What is the control group science?control group, the standard to which comparisons are made in an experiment. … A typical use of a control group is in an experiment in which the effect of a treatment is unknown and comparisons between the control group and the experimental group are used to measure the effect of the treatment.
Article first time published onWhy were trials taken and averaged penny labs?
Why were so many trials taken and averaged? So many trials were taken because if one i’d the trials wasn’t accurate, the average would be a better tool to determine results than one inaccurate trial. In this experiment, what was your control group? The control group was the penny tested with tap water.
How will the surface tension affect the number of drops that can fit on a penny?
You should find that plain tap water produces a much larger, stable drop of water on top of the penny than the soapy water does. This is because plain tap water has higher surface tension, so the surface is “stronger” and can hold together a larger drop.
Why does soap lower surface tension?
Soap molecules are composed of long chains of carbon and hydrogen atoms. … This separates the water molecules from each other. Since the surface tension forces become smaller as the distance between water molecules increases, the intervening soap molecules decrease the surface tension.
Why does a penny hold more drops of water than alcohol?
Alcohol molecules can meet at areas where they would not attract as strongly. The water is more attracted to itself than to the metal of the penny. The alcohol is a bit less attracted to itself so it spreads more on the penny.
How do intermolecular forces affect the shape of a drop?
A typical molecule in the interior of the droplet is surrounded by other molecules that exert attractive forces from all directions. … Because a sphere has the smallest possible surface area for a given volume, intermolecular attractive interactions between water molecules cause the droplet to adopt a spherical shape.
Why did the dome break when soap was added?
This is because plain tap water has higher surface tension, so the surface is “stronger” and can hold together a larger drop. Adding soap lowers the water’s surface tension so the drop becomes weaker and breaks apart sooner.
What is the difference between force of cohesion and force of adhesion?
The force of cohesion is defined as the force of attraction between molecules of the same substance. The force of adhesion is defined as the force of attraction between different substances, such as glass and water.
What is the difference between adhesion and cohesion and give an example of each?
Cohesion is the property of like molecules (of the same substance) to stick to each other due to mutual attraction. Adhesion is the property of different molecules or surfaces to cling to each other. For example, solids have high cohesive properties so they do not stick to the surfaces they come in contact.
What is cohesive and adhesive forces?
Attractive forces between molecules of the same type are called cohesive forces. Attractive forces between molecules of different types are called adhesive forces. Cohesive forces between molecules cause the surface of a liquid to contract to the smallest possible surface area.
How many drops of water and soap can fit on a penny?
Our results were interesting. I knew that the oil should have less surface tension than the water, but we had equal results – 23 drops for each. Soapy water had the least surface tension. We were only able to get 11 drops of soapy water on the penny.
What is a penny made of?
Pennies are made of zinc coated with copper. Only nickels are one solid material—that same 75% copper/25% nickel alloy.
What is the dependent variable in the penny drop lab?
The independent variable in the experiment is the soap and the dependent variable in the experiment is the number of water drops on the surface of the penny. The control is the penny without soap.
What is a control in an experiment?
When conducting an experiment, a control is an element that remains unchanged or unaffected by other variables. It is used as a benchmark or a point of comparison against which other test results are measured. … The control group, however, receives no medicine or a placebo.
What was the purpose of the control tube in this experiment?
The major role of control tube is to reduce the variability due to unwanted/unknown factors of the experiment.
Why do we use control in an experiment?
A control is important for an experiment because it allows the experiment to minimize the changes in all other variables except the one being tested.
What does control mean in scientific method?
A scientific control is an experiment or observation designed to minimize the effects of variables other than the independent variable (i.e. confounding variables). This increases the reliability of the results, often through a comparison between control measurements and the other measurements.
What are controls and variables in a scientific experiment?
A control variable is any factor that is controlled or held constant in an experiment. A control variable is any factor that is controlled or held constant during an experiment.
What is control in research design?
Control refers to the effort by the researcher to remove the influence of any extraneous, confounding variable on the DV under investigation.
Which best describes a control group in an experiment?
A control group is a group separated from the rest of the experiment where the independent variable being tested is not exposed.
What are examples of control groups?
A simple example of a control group can be seen in an experiment in which the researcher tests whether or not a new fertilizer has an effect on plant growth. The negative control group would be the set of plants grown without the fertilizer, but under the exact same conditions as the experimental group.
How do you identify the control group in an experiment?
The control group is composed of participants who do not receive the experimental treatment. When conducting an experiment, these people are randomly assigned to be in this group. They also closely resemble the participants who are in the experimental group or the individuals who receive the treatment.
