Question

create an appropriately labeled bar graph to illustrate the sample means for the penny with and without soap within 95% confidence (+/- 2 sem). dont forget a title that includes the independent and dependent variables and axes labels with units.

1. make a claim about how soap affects hydrogen bonds between water molecules.
2. using data from this experiment, provide evidence that supports the claim.
3. using background knowledge and data from this lab, provide reasoning that uses the evidence to justify the claim.

Explanation:

1. Soap disrupts hydrogen bonds between water molecules. Soap is a surfactant with a hydrophilic (water - loving) head and a hydrophobic (water - fearing) tail. The hydrophobic tails of soap molecules can insert themselves between water molecules, breaking the hydrogen - bonding network.
2. Evidence would be in the form of data from the experiment such as differences in surface tension measurements (since hydrogen bonds contribute to surface tension). If the surface tension is lower when soap is present on the penny (compared to without soap), it indicates that the hydrogen bonds have been disrupted. For example, if the number of water drops that can fit on a penny without soap is higher than with soap, it shows that the cohesive forces due to hydrogen bonds are weaker with soap.
3. Reasoning: Surface tension is a result of the cohesive forces (hydrogen bonds) between water molecules. When soap is added, the surfactant molecules interfere with these forces. The data showing a change in the property related to surface tension (e.g., drop - holding capacity of the penny) justifies the claim that soap disrupts hydrogen bonds. Since soap molecules break up the regular arrangement of water molecules, the hydrogen - bonding network is compromised.

Answer:

1. Claim: Soap disrupts hydrogen bonds between water molecules.
2. Evidence: Differences in surface - tension related measurements (e.g., number of water drops on penny) between penny with and without soap, where lower surface - tension related values with soap indicate disrupted hydrogen bonds.
3. Reasoning: Soap, as a surfactant, interferes with the cohesive forces (hydrogen bonds) between water molecules, as shown by the changes in surface - tension related data from the experiment.