Question

1. An amphiphilic molecule has both hydrophilic and hydrophobic properties. Why must soap molecules be amphiphilic to be effective and removing COVID-19 during handwashing?

2. Why is washing your hands with water alone is not effective in removing a virus like COVID-19? Explain your answer in terms of the lipid coating of the virus.

3. Hand sanitizers are generally made with isopropyl alcohol, (CH₃)₂CHOH, and sometimes are made with ethyl alcohol, CH₃CH₂OH. These sanitizers can be effective against a virus such as COVID-19, when used properly. Suggest a reason why hand sanitizer can be effective against COVID-19 and explain the answer based on the interparticle forces concept.

4. Why might washing with soap and water be more effective in removing COVID-19 than using a hand sanitizer?

Answer 1

Q1

COVID 19 virus contains a coat made up of lipid molecules. A soap molecule is pin-shaped, tail is hydrophobic and the head is hydrophilic. The hydrophobic tail of the soap molecule has an affinity for the hydrophobic lipid molecules present on the virus coat surface. Therefore, the hydrophobic tail of the soap molecule will be inserted or interact with the viral coat; this interaction ruptures the virus coat, wakens the interactions between virus coat and skin and removes the virus from the hand (figure1).

Figure 1.

Q2.

Water molecules interact with the hydrophilic molecules and can compete for binding with other hydrophilic molecules. In COVID viruses, lipids molecules interact with their hydrophobic tail and form the viral coat. Being the hydrophilic molecule water will try to move away from the hydrophobic lipid molecules of coat and will not compete with its binding partner to break the viral coat (figure 2).

Figure 2.

Q3.

The interparticle forces concept depicts the interaction between lipid molecules of the coat of viruses. Alcohol hand sanitizer damages COVID by two ways

1. Alcohol denatures the spike protein present on the viral coat.

2. Alcohol breaks the interaction between lipid molecules of the viral coat.

Q4.

It just depends on the user's practice. Alcohol is a volatile solvent, therefore, it evaporates rapidly as long as it exposes to the air. Hence, it may not cover the whole surface of the hand and may not be as effective as soap.