A balloon contains 7.36 g of oxygen gas \( \left(\mathrm{O}_{2}\right) \). How many oxygen molecules are in the balloon? The Periodic Table A. \( 4.43 \times 10^{24} \) molecules B. \( 1.38 \times 10^{23} \) molecules C. 236 molecules D. 15 molecules

To find out how many oxygen molecules are in 7.36 g of oxygen gas (\( \mathrm{O}_{2} \)), we first need to determine the number of moles of oxygen. The molar mass of \( \mathrm{O}_{2} \) is approximately 32 g/mol (16 g/mol for each oxygen atom). Thus, the number of moles of \( \mathrm{O}_{2} \) in the balloon is \( \frac{7.36 \text{ g}}{32 \text{ g/mol}} \approx 0.23 \text{ moles} \). Now, using Avogadro's number, which is \( 6.022 \times 10^{23} \) molecules/mol, we can calculate the number of molecules: \[ 0.23 \text{ moles} \times 6.022 \times 10^{23} \text{ molecules/mol} \approx 1.38 \times 10^{23} \text{ molecules}. \] So, the correct answer is B. \( 1.38 \times 10^{23} \) molecules. Did you know that oxygen makes up about 21% of the Earth's atmosphere? That’s a huge amount of oxygen, and it’s vital for life! The oxygen we breathe is produced mainly by plants during photosynthesis, where they absorb carbon dioxide and sunlight to create energy while releasing oxygen. It's a perfect example of nature's balance! On a practical note, if you're ever trying to calculate the number of molecules in a gas, just remember the steps: find the molar mass, convert grams to moles, and then multiply by Avogadro's number. It's a common mistake to forget the conversion to moles, so keep an eye on your units!