# A glass of water contains 0.45mM O2. How many millilitres of oxygen gas at STP are dissolved in 300.0 mL of this water ?

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The volume of a gas (V) is influenced by the amount of substance (n) and the pressure (P) and temperature (T) of the environment where the measurement is being made. The relation for determining the volume is V = (n*R*T)/P where R is a constant called the universal gas constant equal to 8.3145 J/(mol*K)

The volume of 1 mole of an ideal gas at STP is 22.4 liters. The glass of water contains 0.45 mM of oxygen. The volume of 0.45 mM of oxygen is equal to 22.4*0.45/1000 = 0.01008 liters = 10.08 mL.

There are 10.08 mL of oxygen dissolved in the glass of water.

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i am confused the supposed correct answer is 3.0 mL O2 (answer key)