Question

1. make a claim about how soap affects hydrogen bonds between water molecules.

• soap disrupts hydrogen bonds between water molecules.

1. using data from this experiment, provide evidence that supports the claim.
2. using background knowledge and data from this lab, provide reasoning that uses the evidence to justify the claim.

Explanation:

1. Soap contains surfactants which have a hydrophilic (water - loving) head and a hydrophobic (water - fearing) tail. These surfactants can insert themselves between water molecules, thus disrupting the hydrogen bonds that hold water molecules together.
2. Evidence would likely come from the experiment data such as the number of water droplets that can stay on a penny with and without soap. If the number of droplets is lower with soap, it indicates a change in the surface - tension properties of water caused by the disruption of hydrogen bonds.
3. Background knowledge includes the concept of hydrogen bonds in water (weak electrostatic attractions between the hydrogen of one water molecule and the oxygen of another). The data from the lab (e.g., differences in surface - tension related measurements like the number of droplets on a penny) can be used to reason that the presence of soap leads to a decrease in the cohesive forces between water molecules due to the disruption of hydrogen bonds.

Answer:

1. Soap disrupts hydrogen bonds between water molecules.
2. Evidence: [Describe relevant data from the experiment, e.g., lower number of water droplets on penny with soap compared to without].
3. Reasoning: Hydrogen bonds give water its surface - tension properties. Soap's surfactants interfere with these bonds, as shown by the experimental data changes in surface - tension related measurements.