Answer:
69.5 g/mol
Explanation:
Pre-Solving
We are given that a gas has a mass of 7.60 g and has a mass of 2.45 L at STP. We want to calculate the molar mass of this gas.
Since we want the molar mass, we need to find how many moles of gas there are.
Recall that STP = standard temperature and pressure, which is 273K and 1.00 atm.
So, we can use PV = nRT in order to find how many moles of gas there are.
Solving
Substitute the values into the equation.
[tex]1.00 atm * 2.45 L = n * 0.0821 \frac{atmL}{molK} * 273 K[/tex]
[tex]n = \frac{1.00 atm * 2.45 L }{0.0821 \frac{atmL}{molK} * 273K } = 0.10931009 mol[/tex] (do not round yet)
Now, divide the mole value found by the grams given.
So:
[tex]\frac{7.60 g}{0.10931009 mol} = 69.5 g/mol[/tex] (rounded to three sig figs).
