Lab Experiment 2- Mass Conservation and Analysis of a Crystalline Hydrate PDF

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Laboratory Report Experiment 2. Mass Conservation and Analysis of a Crystalline Hydrate Chem 134 Laboratory Section # ____________

Name: ______________________________ Date: ____________________

Chemistry 134

Experiment 2

Data and Results Part 1. Conservation of Mass Total mass before mixing: ____________________ Observation of 1st reaction, between 1.0 M CaCl2 and 1.0 M Na2CO3.

Write and balance a chemical equation for the 1st reaction using the following description: aqueous calcium chloride and aqueous sodium carbonate are mixed to produce aqueous sodium chloride and solid calcium carbonate

Total mass after 1st reaction: __________________ Is mass conserved in the first reaction?

Observation of 2nd reaction, between reaction products from above and 3 M H2SO4.

Write and balance a chemical equation for the 2nd reaction using the following description: solid calcium carbonate and aqueous sulfuric acid are mixed to produce solid calcium sulfate, liquid water, and gaseous carbon dioxide

Total mass after 2nd reaction: _______________ Is mass conserved for the second addition of reagents? If not, how could you verify mass conservation by modifying the procedure?

University of Michigan-Dearborn

27

Chemistry 134

Experiment 2

Part 2. Analysis of a Crystalline Hydrate Unknown Code ______________________ Table 1. Mass of empty crucibles. parameter

Crucible 1

Crucible 2

mass empty crucible (g)

Table 2. Mass unknown before heating. parameter

Sample 1

Sample 2

mass crucible + unknown (g) mass empty crucible (g) from Table 1

mass unknown (g)

Observation. Appearance of the sample in the crucible before heating.

Table 3. Mass anhydrous unknown and crucible. parameter

Crucible 1

Crucible 2

1st heating mass (g) 2nd heating mass (g) 3rd heating mass (g) 4th heating mass (g) mass crucible + anhydrous unknown (g)

Observation. Appearance of the sample in the crucible after heating.

University of Michigan-Dearborn

28

Chemistry 134

Experiment 2

Table 4. Mass anhydrous unknown. parameter mass crucible + anhydrous unknown (g)

Sample 1

Sample 2

from Table 3

mass empty crucible (g) from Table 1

mass anhydrous unknown (g) Table 5. Mass of water lost. parameter

Sample 1

Sample 2

mass unknown (g) from Table 2

mass anhydrous unknown (g) from Table 4

mass water lost (g) Calculate the %hydration in the unknown crystalline hydrate for each sample. Calculate the average value for the %hydration. Show all work. Sample 1

Sample 2

Average

Calculate the %hydration for each common crystalline hydrate and complete the table. formula

%hydration

KAl(SO4)2·12H2O

Show the calculation for the %hydration of green vitriol.

CuSO4·5H2O MgSO4·7H2O FeSO4·7H2O CaSO4·2H2O Na2CO3·H2O University of Michigan-Dearborn

29

Chemistry 134

Experiment 2

Research the color of each crystalline hydrate in Table 2 in the procedure and the color of its corresponding anhydrous salt. Complete the table. formula of hydrate

color of hydrate

formula of anhydrous salt

color of anhydrous salt

KAl(SO4)2·12H2O CuSO4·5H2O MgSO4·7H2O FeSO4·7H2O CaSO4·2H2O Na2CO3·H2O Identify the unknown based on the average value for its %hydration and its appearance, both before and after heating. Select from the compounds provided in Table 2 in the procedure. Explain your choice.

Calculate the relative error(%) of the experimental %hydration.

List one possible source of error that may lead to a high value for %hydration.

List one possible source of error that may lead to a low value for %hydration.

University of Michigan-Dearborn

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