Chemistry Solutions Preparation Quiz

Questions and Answers

Which method is more accurate for preparing a 1M NaCl solution: dissolving NaCl in 300ml of water and then adding 700ml, or dissolving NaCl in a small volume of water and making the final volume up to 1L? Justify your choice.

The second method is more accurate because it ensures that the final volume is exactly 1L after dissolving, which maintains the correct molarity.

Describe the steps to prepare 50ml of a 6% NaCl solution from solid NaCl.

Weigh 3g of solid NaCl, then dissolve it in a small amount of water. Finally, add water until the total volume reaches 50ml.

Explain how to prepare 100ml of a 0.4M HCl solution from concentrated HCl with a concentration of 36% w/w and a specific gravity of 1.15.

Calculate the mass of concentrated HCl needed, which is 12.3ml, then dilute it to 100ml with distilled water.

What is the procedure to make a 1.5 w/v% NaCl solution in a volume of 50ml?

<p>Weigh 0.75g of solid NaCl and dissolve it in enough water to make the total volume 50ml.</p> Signup and view all the answers

Outline the steps to prepare a 0.08M NaOH solution in 50ml using solid NaOH.

<p>Weigh 0.32g of NaOH and dissolve it in a small volume of water, then add water to make up the volume to 50ml.</p> Signup and view all the answers

Study Notes

Preparation of NaCl Solutions

For a 1M NaCl solution, the molar mass of NaCl is 58.5g, making it essential to accurately measure this amount.
Method a: Mixing NaCl with water then diluting may introduce measurement errors due to the volume changes during dissolution.
Method b: Dissolving NaCl in a small amount of water and then diluting to a final volume of 1L ensures accurate molarity as the final volume reflects the total solvent.

Preparation of 6% NaCl Solution

To prepare 50ml of a 6% NaCl solution, calculate the amount of NaCl needed.
6% w/v means 6g of NaCl is required per 100ml solution, thus 3g of NaCl is needed for 50ml.

Preparation of 0.4 M HCl Solution

Starting with concentrated HCl (36% w/w, density = 1.15), determine the amount needed for dilution.
Calculate the molarity of concentrated HCl to find the volume required to prepare 100ml of 0.4 M solution.

Preparation of 1.5% w/v NaCl Solution

For a 50ml solution with 1.5% w/v NaCl, measure 0.75g of NaCl (1.5g in 100ml gives 0.75g in 50ml).
Dissolve the measured NaCl in a small volume of water and adjust the total volume to 50ml.

Preparation of 0.08 M NaOH Solution

Calculate the required mass of solid NaOH needed based on its molarity.
For 50ml of 0.08 M NaOH, weigh the appropriate amount of NaOH, dissolve it, and dilute to the desired final volume.

Summary of Key Calculations

Always ensure to consider volume changes after dissolving solids prior to the final dilution.
Accurately calculating the mass or volume of the solute based on the desired concentration is crucial for solution preparation.

Description

Test your knowledge on how to accurately prepare NaCl and HCl solutions. This quiz covers concepts related to molarity and solution preparation techniques. Understand the importance of accurate measuring and following proper procedures in a laboratory setting.