Moving on to the second workbench, you will explore and determine what glassware will be appropriate for you to use. Your lab guide and mentor, Dr. One, will walk you through the process of preparing the solution. You will have the freedom to use the equipment as you like, but only by following Dr. One’s instructions will you be successful in making the right solution. To make sure you can always redo the essential steps of the process, Dr. One will provide you with a fantastic reset button, so you can try again if you make a mistake.
Solve the preparation
In the end, only by carefully ensuring that the right amount of water and ammonium chloride is used can you make the correct solution. Are you prepared for solving how to perform a Solution Preparation?
Part 1: Complete the Labster Lab: Stoichiometry: Avogadro’s number and molecular calculations
Complete all activities and answer all questions within the lab and then complete the questions below:
Purpose: Describe in complete sentences and in your own words, the purpose of this experiment.
Observations: Record three observations from the simulation.
I.
II.
III.
- How do you convert between grams and moles of a specific molecule? Give a specific example to illustrate.
- How do you convert between moles of one substance and moles another substance?
- Balance the following chemical equation:
Na2CO3(aq) + CaCl2(aq) → CaCO3(s) + NaCl(aq)
- Use the balanced chemical equation from the last question to solve this situation: You combine 0.5 moles of Na2CO3 with enough CaCl2 that your compound reacts completely. How many moles of NaCl would you expect this reaction to produce? Show all work below.
Part 2: Complete the Labster Lab: Solution Preparation: From salt to solution
Complete all activities and answer all questions within the lab and then complete the questions below:
- In this lab, you learned how to prepare solutions with a precise concentration. Where in your nursing career might this skill be needed?
- Which piece of glassware did you use to prepare your solution in this lab and why?
- Calculate how many grams of NaCl are required to make 100 mL of a 1 M NaCl solution. Show your work in the space below.
Full Answer Section
The lab consists of two parts. In the first part, students prepare a solution of ammonium chloride (NH4Cl) with a specific concentration. In the second part, students use the prepared solution to perform a series of calculations, such as determining the number of moles of NH4Cl in a given volume of solution, the mass of NH4Cl in a given volume of solution, and the concentration of NH4Cl in a diluted solution.
The lab is designed to help students develop a deeper understanding of the following concepts:
- Stoichiometry
- Avogadro's number
- Molecular calculations
- Molarity
- Dilution
The lab also helps students to develop their laboratory skills, such as measuring, pipetting, and preparing solutions.
Example
In one activity in the lab, students are asked to prepare a 100 mL solution of NH4Cl with a concentration of 0.10 M. To do this, they must first calculate the mass of NH4Cl that is needed. They can do this using the following equation:
mass of NH4Cl = (concentration of NH4Cl) x (volume of solution) x (molar mass of NH4Cl)
The concentration of NH4Cl is 0.10 M, the volume of solution is 100 mL, and the molar mass of NH4Cl is 53.49 g/mol. Therefore, the mass of NH4Cl that is needed is:
mass of NH4Cl = (0.10 M) x (100 mL) x (53.49 g/mol) = 5.35 g
Once the students have calculated the mass of NH4Cl that is needed, they can weigh out the NH4Cl and dissolve it in 100 mL of water.
In another activity in the lab, students are asked to use the prepared NH4Cl solution to determine the number of moles of NH4Cl in a given volume of solution. To do this, they can use the following equation:
number of moles of NH4Cl = (concentration of NH4Cl) x (volume of solution)
The concentration of NH4Cl is known, and the students can measure the volume of solution. Therefore, they can calculate the number of moles of NH4Cl using the above equation.
The Stoichiometry: Avogadro's Number and Molecular Calculations Lab is a valuable tool for students who are learning about stoichiometry, Avogadro's number, and molecular calculations. The lab helps students to develop a deeper understanding of these concepts and to develop their laboratory skills.
Sample Answer
Purpose of the Stoichiometry: Avogadro's Number and Molecular Calculations Lab
The purpose of the Stoichiometry: Avogadro's Number and Molecular Calculations Lab is to introduce students to the concepts of stoichiometry, Avogadro's number, and molecular calculations. Stoichiometry is the study of the quantitative relationships between reactants and products in a chemical reaction. Avogadro's number is the number of particles (atoms or molecules) in one mole of a substance. Molecular calculations are used to determine the number of moles of a substance in a given mass, or the mass of a substance in a given number of moles.