QUESTION
Chemistry Assignment
DATA SHEET I
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Date |
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Name |
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Empirical Formula of Zinc Chloride |
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Partner |
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* Be sure to record all data and perform all calculations using the proper number of significant figures and units. You will be graded upon correct use of significant figures and units.
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Mass of zinc metal…………………………………………………. |
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Mass of evaporating dish………………………………………… |
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Mass of dish and zinc chloride (after evaporation of liquid)………………. |
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1. Determine the mass of the zinc chloride by subtracting the mass of the dish. Mass of zinc chloride……………………………………… |
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2. Determine the mass of chlorine in the compound by subtracting the original mass of the zinc metal. Mass of chlorine…………………………………………… |
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- Determine the percentage of both zinc and chlorine in the compound. Show your work here for full credit. (You may wish to consult your text or the instructor to calculate a percentage.)
(significant figures??)
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Percent zinc ……………………………………………….. |
% |
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Percent chlorine …………………………………………… |
% |
Record these values as per your instructor before you leave the laboratory.
- Determine the number of moles of both zinc and chlorine present in 100.0 grams of the compound. (The percents of zinc and chlorine are the grams of each in 100.0 g of zinc chloride respectively.) Show your work clearly here for full credit (significant figures??).
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Moles of zinc ……………………………………………… |
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Moles of chlorine …………………………………………. |
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DATA SHEET II
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Date |
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Name |
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Empirical Formula Zinc Chloride |
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Partner |
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- Divide both of the mole values by the smaller number of moles to determine the mole ratio. Express these numbers to the proper number of significant figures. (So one of your values should be 1.00 or 1.000.) Show your work here clearly and be sure to include the correct units with your answer for full credit.
- If you used the proper units to do the calculation in #5, the result is a ratio of one element to the other (rounded to the nearest whole number) and allows you to now write the empirical formula of zinc chloride.
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Empirical formula of zinc chloride (We expect you to use proper subscripts in Word®)……………………… |
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The remaining work can be done only after the instructor gives you the class average values as determined from the records of the class results. Remember to use proper significant figures and units throughout.
- Your instructor will most likely e-mail you the class average values. Write them here…
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Class average % Zn…… |
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Class average % Cl….. |
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- Determine the moles of zinc and moles of chlorine in 100.0 grams of zinc chloride. (Show work and use significant figures for full credit)
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Moles of zinc (class average) ……………………………… |
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Moles of chlorine (class average)………………………….. |
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- Determine the empirical formula for the class result, just like you did above for your own data. (Show work clearly and use significant figures for full credit)
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Empirical formula of zinc chloride (from class averages) (We expect you to use proper subscripts in Word®)………………… |
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EMPIRICAL FORMULA OF ZINC CHLORIDE DATA SHEET I
|
Date |
|
|
Name |
|
|
|
|
|
|
|
* Be sure to record all data and perform all calculations using the proper number of significant figures and units. You will be graded upon correct use of significant figures and units.
|
Mass of zinc metal…………………………………………………. |
|
|
Mass of evaporating dish………………………………………… |
|
|
Mass of dish and zinc chloride (after evaporation of liquid)………………. |
|
|
1. Determine the mass of the zinc chloride by subtracting the mass of the dish (recorded above). Mass of zinc chloride……………………………………… |
|
|
2. Determine the mass of chlorine in the compound by subtracting the original mass of the zinc metal. (recorded above) Mass of chlorine…………………………………………… |
|
- Determine the percentage of both zinc and chlorine in the compound. Show your work here for full credit. (You may wish to consult your text or the instructor to calculate a percentage.)
(significant figures??)
|
Percent zinc ……………………………………………….. |
% |
|
Percent chlorine …………………………………………… |
% |
Record these values as per your instructor before you leave the laboratory.
- Determine the number of moles of both zinc and chlorine present in 100.0 grams of the compound. (The percents of zinc and chlorine are the grams of each in 100.0 g of zinc chloride respectively.) Show your work clearly here for full credit (significant figures??).
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Moles of zinc ……………………………………………… |
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Moles of chlorine …………………………………………. |
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DATA SHEET CONTINUED
- Divide both of the mole values by the smaller number of moles to determine the mole ratio. Express these numbers to the proper number of significant figures. (So one of your values should be 1.00 or 1.000.) Show your work here clearly and be sure to include the correct units with your answer for full credit.
- If you used the proper units to do the calculation in #5, the result is a ratio of one element to the other (rounded to the nearest whole number) and allows you to now write the empirical formula of zinc chloride.
|
Empirical formula of zinc chloride (We expect you to use proper subscripts in Word®)……………………… |
|
The remaining work can be done only after the instructor gives you the class average values as determined from the records of the class results. Remember to use proper significant figures and units throughout.
- Your instructor will most likely e-mail you the class average values. Write them here…
|
Class average % Zn…… |
|
Class average % Cl….. |
|
- Determine the moles of zinc and moles of chlorine in 100.0 grams of zinc chloride. (Show work and use significant figures for full credit)
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Moles of zinc (class average) ……………………………… |
|
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Moles of chlorine (class average)………………………….. |
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- Determine the empirical formula for the class result, just like you did above for your own data. (Show work clearly and use significant figures for full credit)
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Empirical formula of zinc chloride (from class averages) (We expect you to use proper subscripts in Word®)………………… |
|
EMPIRICAL FORMULA OF ZINC CHLORIDE REPORT SHEET
- At the end of step 4 in the procedure, you have a white solid (zinc chloride).
- Should this white solid have a mass that is more or less than the mass of the zinc metal you started out with?
- Explain why.
- By the end of calculation number 2, you have the mass of each element in the compound. Why do we not use the ratio of these masses to get the empirical formula?
- The most likely error in this experiment lies in obtaining the mass of the chlorine. (You should assume that balance measurements and arithmetic calculations are correct and consider experimental sources of error)
- Speculate as to how someone may obtain a mass of chlorine that is too large.
- Speculate as to how someone may obtain a mass of chlorine that is too low.
| Subject | Chemistry | Pages | 2 | Style | APA |
|---|
Answer
DATA SHEET I
| Date | Name | |||
| Empirical Formula of Zinc Chloride | Partner | |||
* Be sure to record all data and perform all calculations using the proper number of significant figures and units. You will be graded upon correct use of significant figures and units.
| Mass of zinc metal…………………………………………………. | 1.627 |
| Mass of evaporating dish………………………………………… | 46.649 |
| Mass of dish and zinc chloride (after evaporation of liquid)………………. | 49.853 |
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1. Determine the mass of the zinc chloride by subtracting the mass of the dish. Mass of zinc chloride……………………………………… |
3.204 |
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2. Determine the mass of chlorine in the compound by subtracting the original mass of the zinc metal. Mass of chlorine…………………………………………… |
1.577 |
- Determine the percentage of both zinc and chlorine in the compound. Show your work here for full credit. (You may wish to consult your text or the instructor to calculate a percentage.)
% of Zinc = x 100 = 50.7801%
% of Chlorine = x 100 = 49.2197%
| Percent zinc ……………………………………………….. | 50.78% |
| Percent chlorine …………………………………………… | 49.22% |
Record these values as per your instructor before you leave the laboratory.
- Determine the number of moles of both zinc and chlorine present in 100.0 grams of the compound. (The percents of zinc and chlorine are the grams of each in 100.0 g of zinc chloride respectively.) Show your work clearly here for full credit (significant figures??).
Moles of Zinc = = 0.7767
Moles of Chlorine = = 1.3883
| Moles of zinc ……………………………………………… | 0.7767 moles |
| Moles of chlorine …………………………………………. | 1.3883 moles |
DATA SHEET II
| Date | Name | |||
| Empirical Formula Zinc Chloride | Partner | |||
- Divide both of the mole values by the smaller number of moles to determine the mole ratio. Express these numbers to the proper number of significant figures. (So one of your values should be 1.00 or 1.000.) Show your work here clearly and be sure to include the correct units with your answer for full credit.
= 1.7875 approx. = 2
= 1
- If you used the proper units to do the calculation in #5, the result is a ratio of one element to the other (rounded to the nearest whole number) and allows you to now write the empirical formula of zinc chloride.
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Empirical formula of zinc chloride (We expect you to use proper subscripts in Word®)……………………… |
ZnCl2 |
The remaining work can be done only after the instructor gives you the class average values as determined from the records of the class results. Remember to use proper significant figures and units throughout.
- Your instructor will most likely e-mail you the class average values. Write them here…
| Class average % Zn…… | 47.536 | Class average % Cl….. | 52.464 |
- Determine the moles of zinc and moles of chlorine in 100.0 grams of zinc chloride. (Show work and use significant figures for full credit)
Moles of Zinc = = 0.7271
Moles of Chlorine = = 1.4798
| Moles of zinc (class average) ……………………………… | 0.7271 moles |
| Moles of chlorine (class average)………………………….. | 1.4798 moles |
- Determine the empirical formula for the class result, just like you did above for your own data. (Show work clearly and use significant figures for full credit)
Ratios between Zn and Cl:
= 1
= 2.04 approx. to 2.
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Empirical formula of zinc chloride (from class averages) (We expect you to use proper subscripts in Word®)………………… |
ZnCl2 |
EMPIRICAL FORMULA OF ZINC CHLORIDE REPORT SHEET
- At the end of step 4 in the procedure, you have a white solid (zinc chloride).
- Should this white solid have a mass that is more or less than the mass of the zinc metal you started out with?
- Explain why.
Answer: The white solid should have more mass than the mass of the Zinc metal at the start of the experiment (Tee & Fray, 2013).
Reason: Since we are combining the masses of Zinc and Chlorine together to form the mass of Zinc Chloride (Uden et al., 1986).
- By the end of calculation number 2, you have the mass of each element in the compound. Why do we not use the ratio of these masses to get the empirical formula?
Answer: Empirical formula denotes the lowest ratio of atoms of elements constituting a compound and not the masses of the individual elements in the compound (Wilcox et al., 2015).
- The most likely error in this experiment lies in obtaining the mass of the chlorine. (You should assume that balance measurements and arithmetic calculations are correct and consider experimental sources of error)
- Speculate as to how someone may obtain a mass of chlorine that is too large.
If one does not allow the chlorine sufficient time on the burner to combine into the white powder, there are chances that the mass of the chlorine obtained may too large since zinc chloride was not formed fully (Wilcox et al., 2015).
- Speculate as to how someone may obtain a mass of chlorine that is too low.
If one allowed the zinc chloride compound to stay on the burner for a long time, the compound can be over boiled, leading to its disintegration (Tee & Fray, 2013).
Reference
Tee, J. K. S. & Fray, D. J. (2013). Reaction of zinc, copper and iron in air and chlorine mixtures. Mineral Processing and Extractive Metallurgy, 113(3), 129-138. https://doi.org/10.1179/037195504225006551
Uden, P., Slatkavitz, K.J., Barnes, R., & Deming, R. (1986). Empirical and molecular formula determination by gas chromatography/microwave-induced plasma atomic emission spectrometry. Analytica Chimica Acta, 180, 401-416.
Wilcox, R. J., Losey, B. P., Folmer, J. C., Martin, J. D., Zeller, M., & Sommer, R. (2015). Crystalline and liquid structure of zinc chloride trihydrate: a unique ionic liquid. Inorganic chemistry, 54(3), 1109–1119. https://doi.org/10.1021/ic5024532
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