Question

When liquids are heated, they turn into gases. The yellow egg yolk present inside the egg is a liquid but when it is heated, it changes into an omelet, which is solid. Why?

• A. Sometimes, liquids turn into solids
• B. Omelet does not follow the above rule
• C. Strictly speaking, the rule does not apply to complex mixtures and egg yolk is a complex mixture
• D. None of the above

Answer 1

The correct option is C Strictly speaking, the rule does not apply to complex mixtures and egg yolk is a complex mixture

The egg still contains more water than protein, but the water is now dispersed in the protein web so it can no longer flow together, turning the liquid egg into a semi-solid. This happens at around ${145}^{o}F$ for egg white and ${150}^{o}F$ for egg yolk. Continued heating causes more bonds to form, leaving less space for the water, that's why after heating the yolk converts in solid omelet.