Solving Stoichiometry Problems: A Step-by-Step Guide
Hey guys! Today, we're diving into how to tackle stoichiometry problems, specifically focusing on filling out a table with compound formulas, quantities, masses, and the number of particles. We’ll break down each compound—H2, NH3, Al2(SO4)3, CO, and O2—step by step. So, grab your calculators and notebooks, and let's get started!
Hydrogen (H2): Finding Mass and Number of Particles from Moles
When dealing with hydrogen (H2), the first thing we need to understand is its molar mass. The molar mass of H2 is approximately 2 grams per mole (g/mol), since each hydrogen atom has a molar mass of about 1 g/mol. Now, if we have 1 mole of H2, calculating the mass is straightforward.
Here's how we do it:
Mass = Number of moles × Molar mass
Mass = 1 mol × 2 g/mol = 2 grams
So, 1 mole of H2 has a mass of 2 grams. Easy peasy, right? Next, we need to figure out the number of particles, which in this case, refers to the number of molecules. To do this, we use Avogadro's number, which is approximately 6.022 × 10^23 particles per mole.
The calculation looks like this:
Number of particles = Number of moles × Avogadro's number
Number of particles = 1 mol × 6.022 × 10^23 molecules/mol = 6.022 × 10^23 molecules
Thus, 1 mole of H2 contains approximately 6.022 × 10^23 molecules. Knowing these basics helps in understanding the quantities involved in chemical reactions. Remember, stoichiometry is all about these quantitative relationships, and mastering these calculations is super important for solving more complex problems later on. So, keep practicing and make sure you're comfortable with these fundamental calculations involving molar mass and Avogadro's number!
Ammonia (NH3): Calculating Moles and Number of Particles from Mass
Let's tackle ammonia (NH3), where we're given a mass of 51 grams and need to find the number of moles and particles. First, we need to calculate the molar mass of NH3. Nitrogen (N) has a molar mass of about 14 g/mol, and hydrogen (H) has a molar mass of approximately 1 g/mol. Since there are three hydrogen atoms in NH3, the molar mass calculation is:
Molar mass of NH3 = 14 g/mol (N) + 3 × 1 g/mol (H) = 17 g/mol
Now that we have the molar mass, we can find the number of moles using the formula:
Number of moles = Mass / Molar mass
Number of moles = 51 g / 17 g/mol = 3 moles
So, 51 grams of NH3 is equal to 3 moles. Great! Next, we’ll determine the number of particles (molecules). Again, we use Avogadro's number:
Number of particles = Number of moles × Avogadro's number
Number of particles = 3 moles × 6.022 × 10^23 molecules/mol = 1.8066 × 10^24 molecules
Therefore, 51 grams of NH3 contains approximately 1.8066 × 10^24 molecules. This exercise shows how to convert mass to moles and then to the number of particles, which is a fundamental skill in chemistry. Always remember to start by finding the molar mass of the compound—this is your key to unlocking the rest of the problem. Practice these conversions, and you’ll become a stoichiometry whiz in no time!
Aluminum Sulfate (Al2(SO4)3): Finding Mass and Moles from Number of Particles
Alright, let's move on to aluminum sulfate (Al2(SO4)3), where we know the number of particles is 1.806 × 10^23. Our goal is to find the number of moles and the mass. First, we need to find the number of moles using Avogadro's number. The formula we'll use is:
Number of moles = Number of particles / Avogadro's number
Number of moles = (1.806 × 10^23) / (6.022 × 10^23 molecules/mol) ≈ 0.3 moles
So, we have approximately 0.3 moles of Al2(SO4)3. Now, to find the mass, we need the molar mass of Al2(SO4)3. Here's how we calculate it:
Molar mass of Al2(SO4)3 = 2 × (Al molar mass) + 3 × (S molar mass) + 12 × (O molar mass)
Molar mass of Al2(SO4)3 = 2 × 27 g/mol + 3 × 32 g/mol + 12 × 16 g/mol = 54 g/mol + 96 g/mol + 192 g/mol = 342 g/mol
Now we can calculate the mass:
Mass = Number of moles × Molar mass
Mass = 0.3 moles × 342 g/mol ≈ 102.6 grams
Thus, 1.806 × 10^23 particles of Al2(SO4)3 corresponds to approximately 0.3 moles, which has a mass of about 102.6 grams. Remember, these calculations involve several steps, including using Avogadro's number and calculating molar mass, so take your time and double-check your work to ensure accuracy! Mastering these steps will make you much more confident in tackling stoichiometry problems.
Carbon Monoxide (CO): Finding Mass and Number of Particles from Moles
Now, let's look at carbon monoxide (CO), where we have 1.5 moles and need to find the mass and the number of particles. First, we calculate the molar mass of CO. Carbon (C) has a molar mass of approximately 12 g/mol, and oxygen (O) has a molar mass of about 16 g/mol. Therefore:
Molar mass of CO = 12 g/mol (C) + 16 g/mol (O) = 28 g/mol
Now we can find the mass using the formula:
Mass = Number of moles × Molar mass
Mass = 1.5 moles × 28 g/mol = 42 grams
So, 1.5 moles of CO has a mass of 42 grams. Next, we need to determine the number of particles (molecules). We use Avogadro's number again:
Number of particles = Number of moles × Avogadro's number
Number of particles = 1.5 moles × 6.022 × 10^23 molecules/mol = 9.033 × 10^23 molecules
Therefore, 1.5 moles of CO contains approximately 9.033 × 10^23 molecules. This problem reinforces the relationship between moles, mass, and the number of particles. Keep practicing these calculations, and you’ll find that they become second nature. Stoichiometry is all about understanding these quantitative relationships, and CO provides a simple yet effective example to practice with.
Oxygen (O2): Calculating Moles and Number of Particles from Mass
Finally, let's consider oxygen (O2), where we're given a mass of 128 grams. Our task is to find the number of moles and the number of particles. First, we need to calculate the molar mass of O2. Since the molar mass of a single oxygen atom (O) is approximately 16 g/mol, the molar mass of O2 is:
Molar mass of O2 = 2 × 16 g/mol = 32 g/mol
Now, we can find the number of moles using the formula:
Number of moles = Mass / Molar mass
Number of moles = 128 g / 32 g/mol = 4 moles
So, 128 grams of O2 is equal to 4 moles. Next, we'll calculate the number of particles (molecules) using Avogadro's number:
Number of particles = Number of moles × Avogadro's number
Number of particles = 4 moles × 6.022 × 10^23 molecules/mol = 2.4088 × 10^24 molecules
Thus, 128 grams of O2 contains approximately 2.4088 × 10^24 molecules. This exercise demonstrates how to convert mass to moles and then to the number of particles, reinforcing these essential stoichiometry skills. Keep practicing these conversions to build your confidence and accuracy in solving chemistry problems. Remember, consistent practice is key to mastering stoichiometry!
By working through these examples, you should now have a clearer understanding of how to convert between moles, mass, and the number of particles for different compounds. Keep practicing, and you'll become a stoichiometry pro in no time! Good luck, and have fun with chemistry!