Chem: Lab Report: Molarity 2h3e3b

LAB REPORT DETERMINING THE MOLARITY OF A SATURATED SOLUTION

PURPOSE To determine the molarity of a saturated solution at room temperature.

DATA & CALCULATIONS DATA COLLECTED Variable volume of solution mass of evaporation dish mass of evaporation dish and NaCl

Value 20 ml 33.12 g 38.48 g

Table 1. The measurements taken for the Lab. The volume of the solution was taken after having filtered the solution through a paper towel, so as to remove any excess sodium that had not incorporated itself into solution. The mass of the sodium chloride was taken after the water was boiled off, leaving only the solute.

CALCULATIONS MASS OF

MOLES OF

DISSOLVED

DISSOLVED

MOLARITY OF SATURATED SOLULTION

Jonathan Sterling

Jonathan Sterling

Variable mass of NaCl dissolved moles of NaCl dissolved molarity of saturated solution

Value 5.36 g NaCl 0.0917 mol NaCl 5 mol/L

Table 2. Contains the calculations for the Lab.

CONCLUSIONS The molarity for sodium chloride at room temperature in water was about 5 mol/L. Of course, the calculations yielded a value closer to 4.6, but when the significant figures were ed for and the value rounded, 5 was the answer.

SOURCES OF ERROR One major source of error is the sputtering of the solution as it was boiled; probably a good amount of sodium chloride was lost during the heating, because little bits popped out of the evaporation dish.

QUESTIONS FOR FURTHER THOUGHT 1. Calculate the molarity of a solution that contains 17.54 g of KCL in 2.00 L of solution.

2. What mass of

would be required to prepare 2.00 L of a 1.50 M solution?

It is firstly obvious that the number of moles required is 3:

Now, the next step is to convert that into grams:

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Jonathan Sterling

3. What is the relationship between temperature and the molarity of a saturated NaCl solution? As the temperature increases, the molarity will decrease, because the volume of the solution becomes greater. This is because when something is colder, it is more condensed, which means that it takes up less space, or has a lesser volume. Since the formula for molarity is

, the

number of moles is divided by a greater quantity as temperature increases; therefore, as temperature increases the molarity decreases.

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