Problem 47 - Chemistry Matter and Change

Question

If your lab procedure instructs you to add two parts acid to each one part of water and you start with 25 mL of water, how much acid will you add, and how will you add it?

Step-by-Step Solution

Answer

You need to add 50 mL of acid to the 25 mL of water following the 2:1 ratio. Always add acid to water for safety reasons. Slowly mix the 50 mL of acid into the water, stirring gently while doing so, and use proper lab safety equipment.

Step 1: Determine the ratio between acid and water

According to the given information, the ratio of acid to water is 2:1. This means that for every one part of water, you need two parts of acid.

Step 2: Calculate the amount of acid needed

You are given 25 mL of water. Since the ratio of acid to water is 2:1, you need to add twice the amount of acid compared to the water. Thus, you will need to add: \( 25\,\text{mL} \times 2 = 50\,\text{mL} \) of acid.

Step 3: Add the acid to the water

While mixing, always remember the safety rule: to "add acid to water" and not the other way around. This is because when adding acid to water, the heat generated during the process is gradually dispersed, preventing any explosions or splashing of acid. Start by slowly adding the calculated 50 mL of acid to the 25 mL of water using a graduated cylinder or a pipette. Make sure to gently stir the mixture while adding the acid to ensure proper mixing and to dissipate any heat generated. Use proper laboratory safety equipment and techniques to protect your skin, eyes, and clothing while handling acids.

Key Concepts

Understanding the Acid to Water Ratio

In chemistry, the "acid to water ratio" is crucial when mixing solutions. It determines how much acid should be mixed with water. The exercise calls for a 2:1 acid to water ratio. This simply means that for every single part of water, you should add two parts of acid.

In practical terms, if you have 25 mL of water, following the 2:1 ratio requires you to add twice that amount of acid. This calculation is straightforward:

• Start with 25 mL of water.
• Multiply by 2 to match the ratio.
• Result: 50 mL of acid to add.

Thus, to adhere to the ratio, you need 50 mL of acid for your 25 mL of water. This ensures the correct concentration and effectiveness of your chemical solution.

Laboratory Safety Procedures

Safety is a top priority when handling acids and other chemicals in the laboratory. Proper methods protect you and maintain a safe work environment. When dealing with acids, remember the important safety rule: "Always add acid to water, not water to acid."

Adding water to acid can cause a violent reaction due to the heat released, potentially leading to dangerous splashes. However, by adding acid to water, the heat dissipates more safely. Here are safety precautions to consider:

• Use protective gear: goggles, gloves, and lab coats.
• Work in a well-ventilated area to avoid inhaling fumes.
• Handle acids with care, using tools like pipettes or graduated cylinders.

Following these steps not only protects you but also ensures the experiment's success and accuracy.

Step-by-Step Solutions for Accurate Mixing

Approaching chemical mixing with a step-by-step method ensures accuracy and safety. Every small phase contributes to the overall outcome, leading to a properly mixed solution. To solve the problem of achieving a 2:1 acid to water ratio, follow these steps:

• Step 1: Determine the acid to water ratio needed for your experiment. In this exercise, it is 2:1.
• Step 2: Calculate the amount of acid required. If you start with 25 mL of water, you need 50 mL of acid.
• Step 3: Carefully mix. Gradually add the measured acid to the water using appropriate laboratory equipment.

Attention to each step ensures the correct mixture and enhances understanding. By following a detailed plan, you'll improve your skills in chemical handling and preparation.