A balloon is filled with 36.6 liters of helium gas. What is the mass of the helium at STP?[?] grams He1 mole = 22.4 L of gas at STPReport your answer with the appropriate number of significant figures.

To solve this problem, we need to use the molar volume of a gas at STP, which is given as 22.4 L/mol.

Step 1: Determine the number of moles of helium in the balloon.

We know that 1 mole of gas at STP occupies 22.4 L. So, the number of moles of helium in the balloon can be calculated as follows:

Number of moles = Volume of helium / Molar volume at STP Number of moles = 36.6 L / 22.4 L/mol = 1.6339 moles

Step 2: Calculate the mass of helium.

The molar mass of helium (He) is approximately 4 g/mol. Therefore, the mass of helium in the balloon can be calculated by multiplying the number of moles by the molar mass:

Mass of helium = Number of moles * Molar mass of helium Mass of helium = 1.6339 moles * 4 g/mol = 6.5356 g

Step 3: Report the answer with the appropriate number of significant figures.

The volume of helium (36.6 L) has three significant figures, and the molar volume at STP (22.4 L/mol) has three significant figures. Therefore, our final answer should also have three significant figures.

So, the mass of the helium in the balloon at STP is 6.54 g.