Scoring Rubric:
Lab: Decomposition of a Hydrate
Name__________________________________
Date___________ Block____
(for some items, maximum points are in parentheses)
Criteria
Points
All changes made in chemical formulas for reactant used and products formed (11 max.)
Data in Data Table are entered in the appropriate number of sig. figs. (12 max.)
Calculation of gfm for each compound in the chemical equation:
correct element symbol (8 max.)
correct number of particles of each element (8 max.)
correct atomic mass used (inc. sig. figs.) (8 max.)
correct calculations done (11 max.)
answers in appropriate sig. figs. (3 max.)
Calculation of number of moles CoCl2 ∙ 6 H2O(s) used in each trial:
correct starting mass used
correct conversion factor used
all units cancelled where possible
correct answer with sig. figs and unit
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_____
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3
3
3
3
2
2
2
2
1
1
1
1
0
0
0
0
3
3
3
3
2
2
2
2
1
1
1
1
0
0
0
0
correct starting mass used
correct conversion factor used
all units cancelled where possible
correct answer with sig. figs and unit
3
3
3
3
2
2
2
2
1
1
1
1
0
0
0
0
correct starting mass used
correct mass-mole conversion factor used
correct mole ratio used
all units cancelled where possible
correct answer with sig. figs and unit
3
3
3
3
3
2
2
2
2
2
1
1
1
1
1
0
0
0
0
0
Calculation of Average Values of reactant and products:
Average Mass of CoCl2 ∙ 6 H2O(s) used
Average mass of CoCl2(s) formed
Average mass of H2O(g) formed
Average number of moles H2O(g) actually formed
Theoretical average mass of H2O(g) expected to be formed
Theoretical average number of moles H2O(g) expected to be formed
3
3
3
3
3
3
-
-
0
0
0
0
0
0
Correct values and units put into equation
Units cancelled
Calculated answer given; % sign given
3
3
3
2
2
2
1
1
1
0
0
0
Comparison of Actual and Theoretical Average Number of Moles H 2O(g) formed:
Stated clearly and unambiguously
3
-
-
0
Calculation of number of moles CoCl2(s) formed in each trial:
correct starting mass used
correct conversion factor used
all units cancelled where possible
correct answer with sig. figs and unit
Calculation of number of moles H2O(g) formed in each trial:
Calculation of theoretical mass of H2O(g) formed:
Calculation of percent yield for each trial:
Explanation (reasons) of differences (or for equality) of the actual and theoretical number of mole H 2O(g) formed:
(Answers must be based on lab results and must be scientifically sound.)
3 2 1 0
Lab procedures written on notebook paper in class attached to back of lab
3
-
-
0