Final answer:
For gas law calculations in chemistry, temperatures in Celsius must be converted to Kelvin by adding 273.15. Thus, a lab temperature of 18 degrees Celsius is equivalent to 291.15 Kelvin.
Step-by-step explanation:
When conducting experiments involving gas laws, it's essential to use the Kelvin temperature scale for measuring temperature. To convert a temperature from the Celsius scale to the Kelvin scale, one needs to add 273.15 to the Celsius temperature. Therefore, if a student measures a gas temperature as 18 degrees Celsius in the lab, for calculations involving gas laws, they will use a temperature of 291.15 Kelvin (18 °C + 273.15 = 291.15 K).