Mole Concept Chemistry: Mass Calculations And Electron Count

Hey guys! Today, we're diving deep into some cool chemistry problems focusing on the mole concept. This is super important in chemistry, as it helps us relate the microscopic world of atoms and molecules to the macroscopic world we can measure in the lab. We'll be tackling three questions that involve calculating masses and electron counts using moles. So, buckle up, and let's get started!

1. Calculating the Mass of a Single Carbon Atom

The first problem is a classic: "Calculate the mass in grams of one carbon atom, given that 1 mole of carbon atoms weighs 12 g." This question really nails the core of the mole concept. We know that the molar mass of carbon, which is the mass of one mole of carbon atoms, is 12 grams. But what does that really mean for a single carbon atom? The mole is a massive number – Avogadro's number (6.022 x 10²³), to be exact. This tells us how many entities (atoms, molecules, ions, etc.) are in one mole. So, to find the mass of a single carbon atom, we need to divide the mass of one mole of carbon by Avogadro's number. Let's break it down step-by-step. First, remember the key definitions: A mole is a unit of amount, just like a dozen, but much, much bigger. Specifically, 1 mole contains 6.022 x 10²³ entities (Avogadro's number). The molar mass is the mass of one mole of a substance, usually expressed in grams per mole (g/mol). For carbon, the molar mass is approximately 12 g/mol. This means that 6.022 x 10²³ carbon atoms have a mass of 12 grams. The key to solving this problem is understanding the relationship between moles, molar mass, and Avogadro's number. We know the mass of a mole of carbon atoms (12 g) and the number of atoms in a mole (6.022 x 10²³). To find the mass of a single atom, we simply divide the mass of the mole by the number of atoms in the mole. So, here's the calculation: Mass of one carbon atom = (Molar mass of carbon) / (Avogadro's number) = 12 g / 6.022 x 10²³ atoms = 1.99 x 10⁻²³ g/atom. Therefore, the mass of a single carbon atom is approximately 1.99 x 10⁻²³ grams. This tiny number highlights just how small atoms really are! This type of calculation is fundamental in chemistry because it allows us to move between the macroscopic world (grams) and the microscopic world (atoms). Understanding this conversion is crucial for many other calculations, including determining the number of atoms in a given mass of a substance or calculating the mass of a single molecule. Mastering this concept is a huge step towards becoming a chemistry whiz! Remember, the mole is your friend, and Avogadro's number is the key to unlocking the atomic world.

2. Determining the Total Number of Electrons in 1.4 g of Nitrogen Gas

Next up, we have this question: "Determine the total number of electrons present in 1.4 g of nitrogen gas." This is a little trickier, but totally doable! We need to consider that nitrogen gas exists as a diatomic molecule (N₂), and each nitrogen atom has 7 electrons. So, we've got a few steps here: calculate the moles of N₂, then the number of N₂ molecules, and finally, the total number of electrons. Let's break it down. First, we need to calculate the molar mass of nitrogen gas (N₂). The atomic mass of nitrogen (N) is approximately 14 g/mol. Since nitrogen gas exists as a diatomic molecule (N₂), the molar mass of N₂ is 2 * 14 g/mol = 28 g/mol. Now, we can calculate the number of moles of N₂ in 1.4 g using the formula: Moles = Mass / Molar mass. So, Moles of N₂ = 1.4 g / 28 g/mol = 0.05 moles. Next, we need to find the number of N₂ molecules using Avogadro's number: Number of molecules = Moles * Avogadro's number. Number of N₂ molecules = 0.05 moles * 6.022 x 10²³ molecules/mol = 3.011 x 10²² molecules. Now, for the final step: calculating the total number of electrons. Each nitrogen atom has 7 electrons. Since N₂ has two nitrogen atoms, each molecule has 2 * 7 = 14 electrons. Therefore, the total number of electrons in 3.011 x 10²² molecules is: Total electrons = Number of molecules * Electrons per molecule. Total electrons = 3.011 x 10²² molecules * 14 electrons/molecule = 4.2154 x 10²³ electrons. So, there are approximately 4.2154 x 10²³ electrons in 1.4 g of nitrogen gas. This problem is a great example of how we use the mole concept to connect mass to the number of particles. It also highlights the importance of paying attention to the molecular formula (N₂) and the number of electrons per atom. Understanding these details is crucial for accurate calculations in chemistry. Remember, always double-check your units and make sure you're using the correct molar masses and Avogadro's number. With practice, these types of calculations will become second nature!

3. Finding the Mass of 0.2 Moles of Water (H₂O)

Last but not least, we have this question: "Find the mass in grams of 0.2 moles of water (H₂O), where H = 1 and O = 16." This one is a bit more straightforward, focusing on the direct relationship between moles and mass. We'll use the molar mass of water to convert moles to grams. To solve this, we'll again need to utilize the concept of molar mass. First, we need to calculate the molar mass of water (H₂O). The atomic mass of hydrogen (H) is approximately 1 g/mol, and there are two hydrogen atoms in a water molecule. The atomic mass of oxygen (O) is approximately 16 g/mol. So, the molar mass of H₂O is (2 * 1 g/mol) + 16 g/mol = 18 g/mol. This means that one mole of water has a mass of 18 grams. Now, we can use this information to find the mass of 0.2 moles of water. We use the formula: Mass = Moles * Molar mass. Mass of 0.2 moles of H₂O = 0.2 moles * 18 g/mol = 3.6 grams. Therefore, the mass of 0.2 moles of water is 3.6 grams. This calculation demonstrates a fundamental application of the mole concept: converting between moles and mass. This skill is essential for preparing solutions, calculating yields in chemical reactions, and many other applications in chemistry. Guys, always remember to identify the molar mass of the compound you're working with, and then you can easily convert between moles and grams using the formula Mass = Moles * Molar mass. This simple equation is a powerful tool in your chemistry toolkit!

So, there you have it! We've tackled three different types of problems using the mole concept. From finding the mass of a single atom to calculating electron counts and converting moles to grams, we've covered some essential skills. Remember, practice makes perfect, so keep working on these types of problems, and you'll become a mole concept master in no time! Keep up the awesome work, and I'll see you in the next chemistry adventure!