Question

Develop a plan for making 1000 \(\mathrm{mL}\) of a 5\(\%\) by volume solution of hydrochloric acid in water. Your plan should describe the amounts of solute and solvent necessary, as well as the steps involved in making the solution.

Short answer

To make 1000 mL of a 5% by volume solution of hydrochloric acid in water, measure 50 mL of hydrochloric acid and 950 mL of water. Use appropriate safety measures like goggles, gloves, and a lab coat. In a 1000 mL volumetric flask, first add the hydrochloric acid and then slowly add the water. Gently swirl the flask to mix the solution thoroughly. Label the flask with the contents and concentration, and ensure proper disposal of used materials according to lab safety guidelines.

Step-by-step solution

Determine the amount of hydrochloric acid needed

We need a 5% by volume solution, so this means we need to have 5% of the final volume, which is 1000 mL, as hydrochloric acid. Calculate 5% of 1000 mL to find the required volume of hydrochloric acid: \(0.05 \times 1000\,\mathrm{mL} = 50\,\mathrm{mL}\).

Determine the amount of water needed

Subtract the volume of hydrochloric acid from the total volume to determine how much water is needed: \(1000\,\mathrm{mL} - 50\,\mathrm{mL} = 950\,\mathrm{mL}\).

Gather materials and safety equipment

To prepare the solution, gather the necessary materials, including: - A 1000 mL volumetric flask - A pipette or graduated cylinder to measure the hydrochloric acid - A dispenser or another graduated cylinder for water - Safety goggles - Gloves - Lab coat or apron Make sure to follow safety procedures, including wearing safety goggles, gloves, and a lab coat or apron to protect yourself from exposure to the hydrochloric acid.

Measure and add hydrochloric acid to the flask

Using the pipette or graduated cylinder, carefully measure 50 mL of hydrochloric acid. Slowly pour the hydrochloric acid into the 1000 mL volumetric flask.

Measure and add water to the flask

Using the dispenser or a different graduated cylinder, carefully measure 950 mL of water. Please note: for safety reasons, it is crucial to add acid to water and not the other way around. This helps to avoid an exothermic reaction that can generate a lot of heat and cause the solution to splatter.

Mix the hydrochloric acid and water

Slowly add the water, measured above, to the volumetric flask containing the hydrochloric acid.

Finalize the solution

Once both the hydrochloric acid and water have been combined in the volumetric flask, mix the contents by gently swirling the flask while securely holding its stopper. Once thoroughly mixed, your 1000 mL of a 5% by volume solution of hydrochloric acid is ready for use. Make sure to label the flask with its contents and concentration and dispose of any used materials according to your lab's safety guidelines.

Key concepts

Solution Concentration

Understanding solution concentration is fundamental in chemistry, and it represents the amount of solute that is dissolved in a given quantity of solvent. It can be expressed in various ways, including percent by volume, molarity, molality, and parts per million (ppm).

In the context of the exercise, the concentration is given as percent by volume, which is the volume of solute divided by the total volume of the solution, multiplied by 100. For instance, a 5% by volume solution of hydrochloric acid (HCl) means that 5 mL of HCl is present in every 100 mL of solution. Hence, to prepare 1000 mL of a 5% solution, one needs 50 mL of hydrochloric acid. The rest of the volume, which is 950 mL, will be water.

Calculating Percent by Volume

Percent by volume is calculated as: \[\text{% by volume} = \left(\frac{\text{Volume of solute}}{\text{Total volume of solution}}\right) \times 100\]For our exercise, the calculation was: \[5\% = \left(\frac{50\,\mathrm{mL}}{1000\,\mathrm{mL}}\right) \times 100\]This measurement helps when you have to prepare solutions with precision, commonly required in laboratory practices and industrial processes.

Volumetric Analysis

Volumetric analysis, also known as titrimetry, involves measuring the volume of a solution to determine the concentration of an unknown substance. It's a key technique in chemistry for standardizing solutions, assessing purity, and conducting quantitative analysis.

In preparing solutions, like the 5% hydrochloric acid solution, precision is essential. Accurate measurements ensure the desired concentration is achieved. Tools such as pipettes, burettes, or volumetric flasks, which allow for precise volume measurements, are staples in volumetric analysis.

Precision in Measurement

We highlight the importance of using a pipette or a graduated cylinder for measuring the HCl and a volumetric flask to obtain the exact final volume. Volumetric flasks are specially designed to contain a precise volume when filled to the mark on their neck. Once the required volumes of acid and water are combined, the solution's concentration will match the intended design of 5% by volume.

Laboratory Safety Procedures

Laboratory safety procedures are critical to prevent injuries and accidents when working with hazardous materials. Handling hydrochloric acid, like in our exercise, requires personal protective equipment (PPE) including safety goggles, gloves, and a lab coat or apron.

When preparing solutions, always follow these key safety guidelines:

• Wear appropriate PPE to protect from splashes or spills.
• Understand the properties of chemicals you're working with.
• Add acid to water, not water to acid, to prevent exothermic reactions that can cause splattering.
• Label containers clearly with contents and concentrations.
• Dispose of chemicals according to your lab's waste disposal protocols.

Remember, safety in the lab is not just a personal responsibility; it's a collective one. Always be mindful of your actions, keeping yourself and your peers safe.