What is the molality of a solution in which 2.3 g #O_2# gas dissolved in 355 g of water?

1 Answer
Jun 11, 2016

Answer:

#0.20m#

Explanation:

Molality can be found using the equation below:

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What you want to do now is determine what the solute and solvent are. A solute is dissolved in the solvent and the solute is the "minor component in a solution."The solvent is usually water or it is the substance that you have more of. In our case, the solute is #O_2# and the solvent is water.

As we can see from the equation, the solute and solvent have the wrong units. Let's start by converting grams of #O_2# to moles of #O_2#. We do this by using the molar mass of #O_2# as a conversion factor.

#2.3cancel"g"O_2xx (1mol O_2)/(32.00cancel"g")= 0.0719 mol O_2#

Now we need kg of solvent instead of the grams that we're given. Let's use this relationship:
www.internetdict.com

#355cancel"g" H_2O xx (1kg)/(1000cancel"g") = .355kg H_2O#

Now all we do is plug the values into the equation like this:

#molality = (0.0719 mol)/(0.355kg)# = #0.20 m#