Mixing Bleach: How to Achieve the Perfect Chlorine Concentration

To achieve a solution of 100 mg per liter available chlorine, how much of 5.25 percent bleach should be mixed with one gallon of water?

• A. 0.5 oz
• B. 1.0 oz
• C. 0.33 oz
• D. 0.25 oz

Answer: (D)

To determine the correct amount of 5.25% bleach required to achieve a concentration of 100 mg per liter of available chlorine in one gallon of water, it is essential to understand the relationship between the concentration of the bleach solution and the final desired concentration. First, we convert 100 mg per liter to ounces. Given that there are approximately 3785 milliliters in one gallon, that's equivalent to 3.785 liters. Since we want 100 mg of chlorine per liter, the total amount of available chlorine needed for one gallon is: 100 mg/L × 3.785 L = 378.5 mg Now, considering that the bleach solution is 5.25% sodium hypochlorite by weight, we first convert this percentage into milligrams per milliliter. The density of typical bleach is close to that of water, allowing us to approximate that 5.25% bleach has about 52.5 mg of available chlorine per milliliter. To find out how many milliliters of the bleach is needed to provide 378.5 mg of chlorine, we can set up the calculation: 378.5 mg ÷ (52.5 mg/mL) ≈ 7.2 m

Understanding the blend of bleach and water to achieve specific chlorine levels isn’t just a number game; it’s an essential part of ensuring public safety. So, let’s get into it! When it comes down to achieving a solution containing 100 mg per liter of available chlorine, practical math comes into play. If you’re gearing up for the Registered Sanitarian Test, mastering these calculations can set you apart!

First, let’s tackle the problem: how would you go about figuring out how much 5.25% bleach to mix with one gallon of water? The answer may seem simple, but as with most things in science, the devil is in the details.

Now, you might be wondering, why do we need to slap ourselves with all these numbers? Well, it’s crucial for understanding the relationship between bleach's concentration and the desired concentration in the solution. Here's a quick overview of the steps you'll take.

To start, the first goal is converting 100 mg/L of available chlorine into a total amount for one gallon of water, which can feel a bit like being thrown into the deep end if you’re not familiar with conversions. But don’t worry. We got this!

Considering that one gallon is approximately 3.785 liters, you want to multiply that by your target concentration of 100 mg/L. Here’s the magic formula:

[ 100 \text{ mg/L} \times 3.785 \text{ L} = 378.5 \text{ mg} ]

That’s the total amount of available chlorine you'll need. Easy enough, right?

Now, here’s where it gets interesting. The bleach solution you’re working with has a concentration of 5.25% sodium hypochlorite by weight. But what does that mean in terms of milligrams per milliliter? Well, since we’re working with a liquid that has a density similar to water, you can think of it like this: for every milliliter of bleach, you’re getting around 52.5 mg of available chlorine.

Here’s the pivotal calculation you’ll need next. To find out how many milliliters of bleach you need to achieve the 378.5 mg of needed chlorine, you can set up this straightforward equation:

[ 378.5 \text{ mg} ÷ (52.5 \text{ mg/mL}) \approx 7.2 \text{ mL}]

That’s right! About 7.2 mL of the 5.25% bleach is what you'll need to mix into your gallon of water to reach the magic number of 100 mg/L available chlorine.

But whoa! Before you dash off to mix it up, let’s convert this into ounces—because honestly, we all think in ounces, right? There's about 29.5735 mL in an ounce, so:

[ 7.2 \text{ mL} ÷ 29.5735 \approx 0.25 \text{ oz} ]

And voila! There you have it! You need to mix approximately 0.25 oz of bleach with one gallon of water. You’ve just navigated through essential calculations that not only boost your knowledge but also sharpen your skills for environmental safety standards.

Now, why is this crucial knowledge? Chlorine is a powerful disinfectant used widely in various scenarios—from sanitizing drinking water to ensuring public spaces are safe from harmful pathogens. Understanding how to mix it correctly matters for health and safety!

You know what? Practicing these kinds of calculations not only prepares you for the Registered Sanitarian Test but also equips you with knowledge that is applicable in real-life situations—whether you find yourself in a lab, a community health setting, or even managing your household cleaning supplies.

So, next time you’re knee-deep in calculations, remember you have all the tools you need to get it right. Understanding how to mix bleach for effective disinfection isn’t just a quiz question; it’s a vital skill for public health! Happy studying! Remember, you’ve got this!