One student who performed the calcium supplement experiment had the following en
ID: 1039174 • Letter: O
Question
One student who performed the calcium supplement experiment had the following
entries in their laboratory notebook:
Table 1. Calcium Supplement Information
mass of beaker: 55:601 g
mass of beaker + sample: 56:223 g
---------------------------------------------------------------------
net mass of supplement:
Table 2. Calcium Carbonate
mass of watch glass + lter paper: 3:570 g
mass of watch glass + lter paper + dry precipitate: 4:117 g
-------------------------------------------------------------------------------------------------------------------------------
net mass CaCO3 recovered:
mass percent CaCO3:
mass percent Ca2+:
Table 3. Section Data
Student CaCO3 Ca2+
1. 44:6%
2. 45:5%
3. 43:9%
4. 44:0%
5. 43:8%
6. 44:9%
7. 44:7%
8. 44:6%
9
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Averages:
(a) Complete Tables 1 - 3.
(b) Add the students results to the Section Data and determine (a) the average mass
percent CaCO3 and average mass percent Ca2+ for the supplement; (b) the sample
standard deviation (s) for the mass percent CaCO3 and mass percent Ca2+; and
(c) the 90% and 95% condence intervals for the mass percent CaCO3 and mass
percent Ca2+.
Explanation / Answer
Table 1. Calcium Supplement Information
mass of beaker: 55:601 g
mass of beaker + sample: 56:223 g
---------------------------------------------------------------------
net mass of supplement:= 0.622 g
Table 2. Calcium Carbonate
mass of watch glass + lter paper: 3:570 g
mass of watch glass + lter paper + dry precipitate: 4:117 g
-------------------------------------------------------------------------------------------------------------------------------
net mass CaCO3 recovered: 0.622 g
mass percent CaCO3: (mass of CaCO3/ total mass)*100
= 100%
mass percent Ca2+:
molar mass of CaCO3=100
molar mass of Ca+2 := 40
number of Ca+2 =2
mass percent of Ca+2 = (number of Ca+2 *molar mass ofCa+2 / molar mass of CaCO3)*100
=(2*40/200)*100
=40%
Table 3. Section Data
Student CaCO3 Ca2+
1. 44:6%
2. 45:5%
3. 43:9%
4. 44:0%
5. 43:8%
6. 44:9%
7. 44:7%
8. 44:6%
Averages= (44.6%+45.5%+43.9%+44.0%+43.8%+44.9%+44.7%+44.6%)/8
= 356/8%
=44.5%
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