If the flask already has water, your measure is going to be higher than expected and MW is going to be higher too.
At first sight, we need to assume 1 atm as atmospheric pressure, probably forgot to write down this value in the Lab. By doing this, we got all values to calculate the MW.
So, for trial 1:
MW = [0.36 g x (0.082 atm x L / K x mol) x 301 K] / (1 atm x 0.125 L) = 71.08 g/mol
Trial 2:
MW = [0.38 g x (0.082 atm x L / K x mol) x 301 K] / (1 atm x 0.125 L) = 75.53 g/mol
Average MW = 73.31 g/mol
Learn more about atmospheric pressure here: https://brainly.com/question/87231
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