Experimental Investigation of Chemical Properties

Categories: Chemistry

Essay, Pages 3 (661 words)

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Purpose

The purpose of this experiment is to become familiar with the use of the general pan balance and the "weigh by balance" method for determining the density of compounds, as well as to determine the precise operation of a pipette. Additionally, this experiment aims to illustrate the mole method, density calculations, dimensional analysis, and the evaluation of deviation and errors in measurements.

Equations

Throughout the experiment, the following equations are used:

Concentration (mol * L^-1) = amount of solute (mol)/volume of solution (L)
Amount (number of moles) = mass/molar mass
Density = mass/volume
Average Deviation (a) = Σ|d| / n
Standard Deviation (Σ) = √(Σd² / (n-1))

Procedure

Experiment A1 was completed exactly as described in Chemistry 217 Home Laboratory Manual, pp. 72-76, with no deviations from the prescribed procedure.

Observations

The compound carbon is lighter than tin.
A small amount of powder remains in the vial when poured into the beaker.
The temperature of the water is approximately 25 degrees Celsius.
The pipette was cleaned until no water residue was visible on the inside.

Results and Explanations

A. Weighting by Difference and the Mole Concept

Measurement	Value
Mass of vial + carbon	6.31 g
Mass of empty vial	4.55 g
Mass of carbon transferred to beaker	1.00 g
Mass of vial + tin	21.80 g
Mass of empty vial	9.80 g
Mass of tin transferred to beaker	1.02 g

Calculations:

Number of moles of carbon transferred to beaker:

1.00 g / 12.01 g/mol = 0.083 mol C (amount of moles of C transferred to beaker)

Number of carbon atoms transferred to beaker:

0.083 mol C x 6.022 x 10²³ atoms/mol = 0.50 x 10²³ atoms of C (number of C atoms transferred to beaker)

Number of moles of tin transferred to beaker:

1.02 g / 118.71 g/mol = 0.0086 mol Tin (amount of moles of Tin transferred to beaker)

Number of tin atoms transferred to beaker:

0.0086 mol Tin x 6.022 x 10²³ atoms/mol = 0.52 x 10²³ atoms of Tin (number of Tin atoms transferred to beaker)

Results:

The average mass of one atom of carbon (in grams):

1.00 g C / 0.50 x 10²³ atom of C = 2.00 x 10^-23 g

The average mass of one atom of tin (in grams):

1.02 g tin / 0.52 x 10²³ atom of tin = 1.96 x 10^-23 g

The ratio, average mass of one atom of tin: average mass of one atom of carbon:

1.96 x 10^-23 g / 2.00 x 10^-23 g = 0.98:1

The correct value of the ratio 1:2 based on theory:

9.983:1

B. Density of Water

Measurement	Value
Volume of water in cylinder	25 mL
Mass of water + cylinder	52.26 g
Mass of empty cylinder	29.18 g
Mass of water in cylinder	23.08 g
Water temperature	25˚C

Calculations:

Density of water at 25˚C:

23.08 g / 25 mL = 0.9232 g/mL

Literature value for density of water at 25˚C: 0.99707 g/mL (as per Chemistry 217 Home Laboratory Manual, pp. 65)

C. Calibration of a Pipette

#	Mass Beaker + Water	Mass Empty Beaker	Mass of Water	Temperature of Water	Density of Water at 25˚C	Volume of Water Dispensed (ml)
1	34.12 g	29.18 g	4.94 g	25˚C	0.99707 g/mL	4.9545 mL
2	34.09 g	29.18 g	4.91 g	25˚C	0.99707 g/mL	4.9244 mL
3	34.12 g	29.18 g	4.94 g	25˚C	0.99707 g/mL	4.9545 mL
4	34.11 g	29.18 g	4.93 g	25˚C	0.99707 g/mL	4.9444 mL
5	34.13 g	29.18 g	4.95 g	25˚C	0.99707 g/mL	4.9645 mL

Calculations:

Deviation (ml) for each trial:

Trial 1: 0.006 mL
Trial 2: -0.024 mL
Trial 3: 0.006 mL
Trial 4: -0.004 mL
Trial 5: 0.016 mL

Average volume dispensed by pipette:

(4.9545 mL + 4.9244 mL + 4.9545 mL + 4.9444 mL + 4.9645 mL) / 5 = 4.94849 mL

Average deviation:

(0.006 mL - 0.024 mL + 0.006 mL - 0.004 mL + 0.016 mL) / 5 = 0.0112 mL

Standard deviation:

√((0.006 mL² + (-0.024 mL)² + 0.006 mL² + (-0.004 mL)² + 0.016 mL²) / (5 - 1)) = 0.0151 mL

Conclusion:

Using the difference method, 0.50 x 10²³ atoms of carbon and 0.52 x 10²³ atoms of tin were transferred to a beaker. The average mass of one atom of carbon and tin was calculated to be 2.00 x 10^-23 g and 1.96 x 10^-23 g, respectively. This resulted in a ratio of the average mass of one atom of tin to carbon as 0.98:1, which did not match the correct theoretical value of 9.983:1.

The density of water at 25 degrees Celsius was found to be 0.9232 g/mL, while the literature value was 0.99707 g/mL. The calibration of a 5 mL pipette using five trials yielded an average volume of 4.94849 mL with a low average deviation of 0.0112 mL, indicating the accuracy of the experiment.

Experimental Investigation of Chemical Properties. (2024, Jan 02). Retrieved from https://studymoose.com/document/experimental-investigation-of-chemical-properties