Question

your Pre-Lab. 1. A 125 mL sample of dry air at 230.0°C is cooled to 100.0°C at constant pressure. What volume with the air occupy at 100.0°C? 2. A 250.0 mL container of gas is at 150.0°C. At what temperature will the gas occupy a volume of 125 mL? (assume constant pressure) 3. An open flask of air is cooled Does it contain more gas molecules before or after cooling? a. Is the pressure the same, greater or less than before it was cooled? b. An open flask of air is heated, stoppered in to cool back to room temperature. a. Does the flask contain the same, more or fewer gas molecules compared to heated condition, and than allowed 4. before it was heated? Is the volume occupied by the gas the same, greater or less than before it was heated? b. c. Is the pressure in the flask the same, greater or less than before the flask was heated? /uno

Answer 1

1)

Given:

Vi = 125 mL

Ti = 230.0 oC

= (230.0+273) K

= 503 K

Tf = 100.0 oC

= (100.0+273) K

= 373 K

use:

Vi/Ti = Vf/Tf

125 mL / 503.0 K = Vf / 373.0 K

Vf = 92.69 mL

Answer: 92.7 mL

2)

Given:

Ti = 150.0 oC

= (150.0+273) K

= 423 K

Vi = 250.0 mL

Vf = 125 mL

use:

Vi/Ti = Vf/Tf

250.0 mL / 423.0 K = 125.0 mL / Tf

Tf = 211.5 K

Tf = -61.5 oC

Answer: -61.5 oC

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