Molar Concentration: Al2(SO4)3 Solution Calculation

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Hey everyone! Today, let's dive into a classic chemistry problem: calculating the molar concentration of a solution. We're given that 17.1 g of Al2(SO4)3 (aluminum sulfate) is dissolved to make 80 ml of solution. Our mission is to find the concentration of this solution in moles per liter (mol/L), which is also known as molarity. Grab your lab coats, and let’s get started!

Understanding Molar Concentration

Before we jump into the calculations, let's make sure we're all on the same page about molar concentration. Molar concentration, or molarity, is a measure of the number of moles of a solute (the substance being dissolved) per liter of solution. It's a super useful way to express the concentration of a solution, especially in chemistry, because it directly relates to the number of molecules or ions present. The formula for molarity (M) is:

M = moles of solute / liters of solution

So, to find the molarity, we need to figure out two things: the number of moles of Al2(SO4)3 and the volume of the solution in liters. Once we have these two values, we can simply plug them into the formula and calculate the molarity. It sounds simple enough, right? But as always, the devil is in the details.

Step 1: Calculate the Number of Moles of Al2(SO4)3

First, we need to convert the mass of Al2(SO4)3 from grams to moles. To do this, we'll use the molar mass of Al2(SO4)3. The molar mass is the mass of one mole of a substance, and it's usually expressed in grams per mole (g/mol). You can find the molar mass by adding up the atomic masses of all the atoms in the chemical formula. For Al2(SO4)3, we have:

  • 2 aluminum (Al) atoms: 2 * 26.98 g/mol = 53.96 g/mol
  • 3 sulfur (S) atoms: 3 * 32.07 g/mol = 96.21 g/mol
  • 12 oxygen (O) atoms: 12 * 16.00 g/mol = 192.00 g/mol

Adding these up, we get:

Molar mass of Al2(SO4)3 = 53.96 + 96.21 + 192.00 = 342.17 g/mol

Now that we know the molar mass, we can convert the mass of Al2(SO4)3 to moles using the following formula:

moles = mass / molar mass

Plugging in the values, we get:

moles of Al2(SO4)3 = 17.1 g / 342.17 g/mol = 0.05 moles (approximately)

So, we have 0.05 moles of Al2(SO4)3. We're halfway there! Isn't this exciting?

Step 2: Convert the Volume of the Solution to Liters

Next, we need to convert the volume of the solution from milliliters (ml) to liters (L). Remember that 1 liter is equal to 1000 milliliters. So, to convert ml to L, we divide by 1000:

liters = milliliters / 1000

In our case, we have 80 ml of solution, so:

liters of solution = 80 ml / 1000 = 0.08 L

Now we know that we have 0.08 liters of solution. Piece of cake!

Step 3: Calculate the Molar Concentration

Now that we have the number of moles of Al2(SO4)3 and the volume of the solution in liters, we can calculate the molar concentration using the formula we discussed earlier:

M = moles of solute / liters of solution

Plugging in the values, we get:

M = 0.05 moles / 0.08 L = 0.625 mol/L

So, the molar concentration of the Al2(SO4)3 solution is 0.625 mol/L. That means there are 0.625 moles of Al2(SO4)3 in every liter of solution. Awesome, right?

Summarizing the Steps

Let's quickly recap the steps we took to solve this problem:

  1. Calculate the molar mass of Al2(SO4)3: We added up the atomic masses of all the atoms in the chemical formula to find the molar mass, which was 342.17 g/mol.
  2. Convert the mass of Al2(SO4)3 to moles: We used the formula moles = mass / molar mass to convert 17.1 g of Al2(SO4)3 to 0.05 moles.
  3. Convert the volume of the solution to liters: We divided 80 ml by 1000 to convert it to 0.08 L.
  4. Calculate the molar concentration: We used the formula M = moles of solute / liters of solution to calculate the molar concentration, which was 0.625 mol/L.

Importance of Molar Concentration

Understanding and calculating molar concentration is fundamental in chemistry for several reasons. It allows us to accurately measure and control the amount of substance in a solution, which is crucial for experiments and reactions. Knowing the molarity helps in stoichiometry calculations, dilutions, and titrations. In labs, molar concentration is used daily for preparing solutions of specific concentrations for various experiments. Without it, chemistry would be a chaotic mess!

Practical Applications

Beyond the lab, molar concentration is essential in various practical applications. In medicine, it's used to prepare intravenous solutions and medications. For example, saline solutions need to have a specific molarity to be compatible with human blood. In environmental science, molar concentration helps in assessing water quality and pollution levels. By measuring the concentration of certain ions or compounds, scientists can determine the safety and purity of water sources. In the food industry, molar concentration is used to control the acidity and pH of food products, ensuring they meet safety and quality standards. So, molar concentration isn't just theoretical—it's used everywhere!

Common Mistakes to Avoid

When calculating molar concentration, there are a few common mistakes you should watch out for. One of the most frequent errors is forgetting to convert the volume of the solution to liters. Always double-check your units before plugging them into the formula. Another mistake is using the wrong molar mass for the solute. Make sure you calculate the molar mass correctly by adding up the atomic masses of all the atoms in the chemical formula. Finally, be careful with significant figures. Use the correct number of significant figures in your calculations to avoid rounding errors. Avoiding these mistakes will make your calculations much more accurate.

Practice Problems

To really master the concept of molar concentration, it's important to practice solving problems. Try working through some additional examples to solidify your understanding. For instance, you could calculate the molarity of a solution made by dissolving 10 g of NaCl in 250 ml of water. Or, you could determine the mass of solute needed to prepare a 0.5 M solution of glucose in 500 ml of water. The more you practice, the more confident you'll become in your ability to solve molar concentration problems. Practice makes perfect, so keep at it!

Conclusion

So, there you have it! We've successfully calculated the molar concentration of an Al2(SO4)3 solution. It might seem a bit daunting at first, but once you break it down into steps, it's totally manageable. Remember to always double-check your units and use the correct formulas. With a little practice, you'll be calculating molar concentrations like a pro in no time. Keep exploring and happy chemistry-ing!