With a 1°C rise, pCO2 changes by which percent?

• A. pCO2 increases by 3%
• B. pO2 decreases by 3%
• C. pH increases by 0.015
• D. pO2 decreases by 7%

Answer: (A)

Temperature alters gas solubility in liquids, with CO2 being especially affected. As temperature rises, CO2 becomes less soluble in plasma, so for the same dissolved CO2 content, the partial pressure of CO2 must increase. This relationship follows Henry’s law and the temperature dependence of the solubility constant, leading to an approximate 3% rise in pCO2 for each 1°C increase in temperature. That’s why the correct choice is pCO2 increasing by about 3%.

The other options don’t fit this specific temperature–solubility effect. Oxygen’s solubility and the pH changes don’t follow this simple 3% per degree rule in the same way, so they’re not the standard quick-answer consequence of a 1°C rise in temperature.