Environmental science558404

LAB 3: PREPARATION AND DILUTION OF SOLUTIONS

Problem1) Based on the substance that was assigned to you, what mass of salt do you need to use to prepare your 50 mL solution?

2) What volume of water do you need to add to prepare a 50 mL diluted solution?

Goals(List three objectives as they relate to the concepts investigated, the scientific method and the techniques used) (3 pts.)

Hypothesis(Include all preliminary calculations needed to determine the mass of solute and volume of water used, you have three chances to obtain the correct answers, 1 point is deducted for every failed trial. You will be given the correct answer after the third trial) (6 pts.)

Your team is assigned one of the following solutions in the table below.

MaterialElectronic scale

Weighing boat

(1) 50 mL graguated cylinder

(1)50 mL volumetric flask

Eye dropper

Spatula

Procedure Part A: Preparation

Establish all the necessary steps to follow in order to prepare 50 mL solution of your assigned salt for the concentration you are given.

State all steps of the physical manipulations needed to create the solution.

Note:Once this is done, you will need to compare your solution to the control solution for your salt.

Part B: Dilution

Write all the necessary steps to follow in order to prepare a 50 mL solution at the 2nd concentration given from the initial solution you prepared in Part 1 by diluting it.

These steps must include preliminary calculations needed in order to determine the volume of the initial solution you will use in preparing your diluted solution as well as how much water you will add. You must also include all manipulations necessary to do it.

ResultsPresent all your measured data in a proper table format.

Note:Calculated entities do not belong in the result section BUT, for this lab, all calculations will be presented in the hypothesis section instead of in the analysis.

Analysis For this particular situation, interpret your results, both your initial and diluted solutions, will require you to compare yours to the respective control solutions. This comparison should be presented in this section.

Conclusion Final answer to the problem.

Note:Limitations and improvements are not required for this lab.

QuestionsMust answer all questions.

1)You have 2 beakers where a red dye has been dissolved in water.

One beaker has a darker color than the other. Your friend thinks that the darker one has more dye. Is he/she right? Why?

2)Make all the calculations required to complete the following table:

Quantity of
solute / Solution
Concentration / Volume
? g / 50g/L / 200mL
2 moles / ? mol/L / 4L
? moles / 2 mol/L / 0.5 L
4 g NaOH / ? mol/L / 500 mL
? g H2SO4 / 0.5 mol/L / 0.25 L
65 g Ba(NO3)2 / 0.5 M / ? L

3)What is the concentration of a 400 mL solution prepared by diluting 50 mL of a 2 mol/L (ie “molar” or “M”) solution?

4)What volume of an 8 M concentrated solution must be diluted to prepare 500 mL of a solution at a conc. Of 0.4 ml/L?

5)How much water do you have to add to dilute a 50g/mL CaCO3 salt solution to make a 100 mL 0.1 mol/L solution from it?

6)Is the Ba(NO3)2 solution you prepared( no2) an electrolytic solution?Why?What is the name given to the NO3 part of the molecule? What is its electric charge?

7)Given Cu(ClO3)2 is a salt that exists, what is the electric charge of the copper ion(é it gives)?

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