Chemical Formula of Zinc Oxide

Purpose – The purpose of this lab experiment is to identify the simplest chemical formula of zinc chloride.

Observations

In this laboratory exercise you measured the mass of an evaporating dish, zinc and zinc chloride in the evaporating dish.  Make a table that shows the masses you measured in the lab.  The table must include a table number and title.  The title should reflect what is in the table.

Table-1

Masses collected for Zinc chloride and Evaporating dish

Item Weighed	Mass (+/-o.o1g)
Empty evaporating dish (M1)	51.97g
Granular Zinc	0.50g
Granular Zinc + Evaporating dish	52.47g

Table-2

Masses obtained for Zinc chloride and Evaporating dish

Item Weighed	Mass(+/-0)
Evaporating dish + Zinc chloride (M2)	53.01g
Zinc chloride (M2-M1)	1.13g
Evaporating dish + Zinc chloride (at end)	52.90g

Calculations

1. Calculate the mass of zinc and chlorine.

Answer- Mass of zinc = 0.50g

       Mass of chlorine = 1.1-0.50

    =0.6g

2. Based on the masses obtained for zinc and chlorine calculate the simplest formula for zinc chloride.

Answer- Simplest formula for Zinc chloride

Mass of zinc= 0.50g

Moles of zinc

Mass of chlorine=0.6g

Moles of chlorine

Thus, the ratio ==0.44705882

3. Write the balanced chemical equation for the formation of zinc chloride from zinc and hydrochloric acid?

Answer-                                                                                                                               /1

4. Using the true chemical formula for zinc chloride, calculate the mass% of Zn and Cl in zinc chloride’?

Answer-molar mass of Zinc + molar mass of chlorine=65.39+35.45

        =100.34g

Mass percent of zinc in zinc chloride  =

    =64.85%

Mass percent of chlorine in zinc chloride=

=35.15%

5. Calculate the % relative error between your experimental ratio (moles of Cl/moles of Zn) and the true ratio for zinc chloride.

 

Questions

In paragraph formatanswer the following questions:

1. Consider the steps in the procedure used for the formation of zinc chloride.  Zinc was first reacted with hydrochloric acid, then zinc chloride was isolated using a steam bath and lastly it was weighed.  What errors could have occurred during the experiment that would cause your simplest formula to be incorrect?  Include at least 2 errors.  In your answer include how the error affected the simplest formula calculation.

2. Which error would cause the largest effect on your result?

3. How could the errors described in question 1 be reduced or eliminated?

Answer- 1. During performing the experiments in laboratory, chances of error are probable to occur. Some errors can happen accidently, by human error by observing the due to environmental factors, instrumental disorders. The error that occurred during the lab experiment is that the compound could be over burned causing the compound to dissolve into the air.

Weight of the compound should be taken right away otherwise it will be evaporated into the air and there will be change in mass or may be in the whole result of the experiment. Calculations may vary.

2. According to my perception, the error which would cause the maximum effect on the result is human error because if by mistake compound gets over burned or without concentrating during the experiment compound gets over heated it will evaporate in air and we will be left with less amount of compound.

3. We can reduce the error, if the weight of compound is done quickly after heating.  Evaporating dish should be immediately taken off from hot plate to reduce overheating of the compound or loss of compound by evaporation in air.

Conclusion(s)- In conclusion the simplest formula is determined by performing this experiment. We get to know about the possible error that may occur while conducting the experiment.              /3

Reference(s)

1. CHEM16682 Applied chemistry1 -1171-6859, Laboratory manual experiment no-5 posted on slate/Sheridan College, Brampton, Ontario (accessed on 14.feb.2017).

Teacher Evaluation of the overall organization of lab report and laboratory performance (Students leave this part blank)

Overall organization of lab report: formatting of chemical and mathematical equations; clarity of answers; spelling and grammar; attention to details; completed cover sheet; use of headers and footers etc.

Laboratory performance:  punctuality; time management; team work; attention to safety; use of personal protection equipment; use of appropriate lab techniques; prepared to conduct lab, lab data book prepared in advance of the lab; cleanup of lab work area.