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1. A student calculated when 1/100 of the hydrated mole of (NH4)3P3H2O to be 1.12 g.
· N=>3*14= 42
· H=>12*1= 12
· P=>1*31=31
· H2O=>3*18=54
· Total Mass =139 g/mol* 1/100=1.39 g
· |1.39-1.12|/1.39=19%
2. A student obtained 1.9 g of Ca (NO3)26H2O when 1/100 of a mole was dehydrated.
· Ca=>1*40 =40 40
· N=>2*14= 28 28
· O=>6*16=96 96
· Total Mass =164 g/mol *1/100 =1.64 g
· |1.64-1.9|/1.64=16%
3. A student obtained 3.76 g of Al2 (SO4)32H2O when 1/100 of a mole was dehydrated.
· Al=>2*27=54 54
· S=>3*32= 96 96
· O=>12*16 =192
· Total Mass =342 g/mol* 1/100=3.42 g
· |3.76-3.42|/3.42=10 %
4. A student calculated when 1/100 of the dehydrated mole of (K2CO3)3H2O to be 1.5 g..
· K=>2*39= 78
· C=>1*12= 12
· O=>6*16= 48
· Total Mass = 138 g/mol* 1/100= 1.38 g
· |1.38-1.5|/1.38= 8.7%
5. A student obtained 1.9 g of Na2(MoO4)2H2O when 1/100 of a mole was dehydrated.
· Na=>2*23= 46
· Mo=>1*96= 96
· O=>4*16= 64
· Total Mass = 206 g/mol* 1/100 =2.06 g
· |2.06-1.9|/2.06= 7.8%
6. A student obtained 3.76 g of Al2 (SO4)32H2O when 1/100 of a mole was hydrated.
· Al=>2*27=54
· S=>3*32= 96
· O=>12*16 =192
· H2o *2=36
· Total Mass =342 g/mol * 1/100 =3.72g
· |3.72-3.76|/3.42=10 %
7. Calculate the % error if the student obtained 42 g and the accepted value (Theo. value) was 40. g.
· %error= _|error|____ *100
Accepted value
· |42-40|/40
· % error=2/40(100)=5.0%
8. Calculate the % error if the student obtained 135 g and the accepted value (Theo. value) was 20 moles of Lithium.
· %error= _|error|____ *100
Accepted value
· 20 moles (7g/mol)=140 g
· % err.=(140-135)/140(100)=3.57%
9. Calculate the % error if the student obtained 220 g of Radon and the accepted value (Theo. value) was one mole.
· %error= _|error|____ *100
Accepted value
· 1 mole (222 g/mol)=222 g
· % err.=(222-220)/222(100)=0.9%
10. Calculate the % error if the student obtained 30 g and the accepted value (Theo. value) was 40 g.
· %error= _|error|____ *100
Accepted value
· % error=10/40(100)=25.0%
11. Calculate the % error if the student obtained 110 g and the accepted value (Theo. value) was 2 moles of Chromium
· %error= _|error|____ *100
Accepted value
· 2 moles (52g/mol)=104 g
· % err.=(110-104)/104(100)=5.77%
12. Calculate the % error if the student obtained 205 g of Gold and the accepted value (Theo. value) was one mole.
· %error= _|error|____ *100
Accepted value
· 1 mole (197 g/mol)=197 g
· % err.=(205-197)/197(100)=4.06%
13. Calculate the % error if the student obtained 626.4 g of Thorium and the accepted value (Theo. value) was three moles.
· %error= _|error|____ *100
Accepted value
· 3 moles (232g/mol)=696 g
· % err.=(696-626.4)/696(100)=10%
14. Calculate the % error if the student obtained 369.6 g and the accepted value (Theo. value) was 2 moles of Protactinium.
· %error= _|error|____ *100
· Accepted value
· 2 moles (231g/mol)=462 g
· % err.=(462-369.6)/462(100)=20%
15. Calculate the % error if the student obtained 238 g of Uranium and the accepted value (Theo. value) was three moles.
· %error= _|error|____ *100
Accepted value
· 3 mole (238 g/mol)=714 g
· % err.=(714-238)/714(100)=66.7%
16. Calculate the % error if the student obtained 290 g of Aluminum and the accepted value (Theo. value) was 10 moles.
· %error= _|error|____ *100
Accepted value
· 10 moles (27g/mol)=270 g
· % err.=(270-290)/270(100)=7%
17. Calculate the % error if the student obtained 369.6 g and the accepted value (Theo. value) was 2 moles of Protactinium.
· %error= _|error|____ *100
Accepted value
· 2 moles (231g/mol)=462 g
· % err.=(462-369.6)/462(100)=20%
18. Calculate the % error if the student obtained 238 g of Uranium and the accepted value (Theo. value) was three moles.
· %error= _|error|____ *100
Accepted value
· 3 mole (238 g/mol)=714 g
· % err.=(714-238)/714(100)=66.7%
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