When water in a syringe boils at 43°C, which factor is primarily responsible for this phenomenon according to the Ideal Gas Law?

• A. The addition of more water molecules increases the boiling point.
• B. A higher concentration of dissolved gases causes water to boil at a lower temperature.
• C. An increase in the volume of water raises its boiling point.
• D. A decrease in pressure inside the syringe lowers the boiling point of water.

Answer: (D)

Verified step by step guidance

1. Recall that the boiling point of a liquid is the temperature at which its vapor pressure equals the external pressure.
2. Understand that according to the Ideal Gas Law, \(P V = n R T\), pressure (\(P\)) is related to the number of gas molecules (\(n\)), volume (\(V\)), and temperature (\(T\)).
3. In a syringe, when the plunger is pulled back, the volume increases, which causes the pressure inside the syringe to decrease if the amount of gas and temperature remain constant.
4. A decrease in pressure lowers the boiling point of water because the vapor pressure needed to boil is reached at a lower temperature.
5. Therefore, the primary factor responsible for water boiling at 43°C in the syringe is the decrease in pressure inside the syringe, not changes in the amount of water, dissolved gases, or volume of water itself.