Tuesday, December 5, 2017

STOIC %YIELD

NOT ANOTHER STOIC PROBLEM


1) Barium sulfate, BaSO4, is made by the following reaction:


Ba(NO3)2(aq) + Na2SO4(aq) à BaSO4(s) + 2NaNO3(aq)
An experiment was begun with 75.00g of Ba(NO3)2 and an excess of Na2SO4. After collecting and drying the product, 63.45g BaSO4 was obtained. Calculate the theoretical yield and percent yield of BaSO4.



2) Aluminum sulfate can be made by the following reaction:
2AlCl3(aq) + 3H2SO4(aq) à Al2(SO4)3(aq) + 6HCl(aq)
It is quite soluble in water, so to isolate it the solution has to be evaporated to dryness. This drives off the volatile HCl, but the residual solid has to be treated to a little over 200°C to drive off all the water. In one experiment, 25.0g of AlCl3 was mixed with 30.0g H2SO4. Eventually, 28.46g of pure Al2(SO4)3 was isolated. Calculate the percent yield.

 ANSWERS:

1.) theoretical yield = 66.98g BaSO4, % yield = 94.73%
2.) % yield = 88.74%




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STOICH 2

 EASY STOICHIOMETRY PROBLEMS

1)      How many moles of sodium atoms correspond to 1.56x1021 atoms of sodium?

2)      How many moles of Al atoms are needed to combine with 1.58 mol of O atoms to make aluminum oxide, Al2O3?


3)      How many moles of Al are in 2.16 mol of Al2O3?



4)      Aluminum sulfate, Al2(SO4)3, is a compound used in sewage treatment plants. 

a.     Construct a pair of conversion factors that relate moles of aluminum to moles of sulfur for this compound

b.     Construct a pair of conversion factors that relate moles of sulfur to moles of Al2(SO4)3

c.       How many moles of Al are in a sample of this compound if the sample also contains 0.900 mol S?

d.     How many moles of S are in 1.16 mol Al2(SO4)3?



5)      How many moles of H2 and N2 can be formed by the decomposition of 0.145 mol of ammonia, NH3?

ANSWERS:

1)      2.59x10-3mol Na atoms  
2)      1.05mol Al                

3)      4.32mol Al

4)      a. 2mol Al/3mol S            b. 3mol S/1mol Al2(SO4)3            c. 0.600mol Al     d. 3.48mol S

5)      0.0725mol N2 and 0.218mol H2
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EASY STOIC PROBLEMS

 EASY STOICHIOMETRY PROBLEMS

1)      How many moles of sodium atoms correspond to 1.56x1021 atoms of sodium?

2)      How many moles of Al atoms are needed to combine with 1.58 mol of O atoms to make aluminum oxide, Al2O3?


3)      How many moles of Al are in 2.16 mol of Al2O3?



4)      Aluminum sulfate, Al2(SO4)3, is a compound used in sewage treatment plants. 

a.     Construct a pair of conversion factors that relate moles of aluminum to moles of sulfur for this compound

b.     Construct a pair of conversion factors that relate moles of sulfur to moles of Al2(SO4)3

c.       How many moles of Al are in a sample of this compound if the sample also contains 0.900 mol S?

d.     How many moles of S are in 1.16 mol Al2(SO4)3?



5)      How many moles of H2 and N2 can be formed by the decomposition of 0.145 mol of ammonia, NH3?

ANSWERS:

1)      2.59x10-3mol Na atoms  
2)      1.05mol Al                

3)      4.32mol Al

4)      a. 2mol Al/3mol S            b. 3mol S/1mol Al2(SO4)3            c. 0.600mol Al     d. 3.48mol S

5)      0.0725mol N2 and 0.218mol H2
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STOICHIOMETRY


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Friday, October 9, 2015

2nd QUARTER EXAM NA!!!

Hi grade 9 GONZAGA, JOGUES, and REGIS!

I hope this site would help you guys. 

Exam coverage: 
Chapter 5: the periodic table
Chapter 6:er ionic trends
Chapter 7: ionic bonding
Chapter 8: covalent bonding
Chapter 9: chemical reactions

Enjoy studying!

XOXO
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2015: BALANCING CHEMICAL EQUATIONS

Chapter 9: Chemical Reactions

Balancing Chemical Equations Worksheet

1. _____ Zn (s) + _____ AgNO3 (aq) →  _____ Zn(NO3)2 (aq) + _____ Ag (s)
2. _____ N2 (g) + _____ H2 (g) → _____ NH3 (g)
3. _____ NaCl (aq) + _____ AgC2H3O2 (aq) → _____ NaC2H3O2 (aq) + _____ AgCl (s)
4. _____ Mg(OH)2 (aq) + _____ H3PO4 (aq) → _____ H2O (l) + _____ Mg3(PO4 )2 (aq)
5. _____ HNO3 (aq) + _____ Ni (s) → _____ Ni(NO3)2 (aq) + _____ H2 (g)
6. _____ Ba(HCO3)2 (s) → _____ BaCO3 (s) + _____ H2O (g) + _____ CO2 (g)
7. _____ BaCl2 (aq) + _____ Na2SO4 (aq) → _____ NaCl (aq) + _____ BaSO4 (s)
8. _____ Al2(CO3)3 (s) → _____ Al2O3 (s) + _____ CO2 (g)
9. _____ Ca (s) + _____ H2O (l) → _____ Ca(OH)2 (aq) + _____ H2 (g)
10. _____ LiHCO3 (s) → _____ Li2CO3 (s) + _____ H2O (g) + _____ CO2(g)
11. _____ N2 (g) + _____ O2 (g) → _____ N2O5 (g)
12. _____ MgBr2 (aq) + _____ KOH (aq) → _____ KBr (aq) + _____ Mg(OH)2 (s)
13. _____ Mn (s) + _____ CuCl (aq) → _____ Cu (s) + _____ MnCl2 (s)
14. _____ Zn (s) + _____ S8 (s) → _____ ZnS (s)
15. _____ NaOH (aq) + _____ H2SO4 (aq) → _____ H2O (l) + _____ Na2SO4 (aq)
16. _____ K (s) + _____ H2O (l) → _____ KOH (aq) + _____ H2 (g)
17. _____ C5H12 (l) + _____ O2 (g) → _____ H2O (g) + _____ CO2 (g)
18. _____ KOH (aq) + _____ H2CO3 (aq) → _____ H2O (l) + _____ K2CO3 (aq)
19. _____ C4H8O2 (l) + _____ O2 (g) → _____ H2O (g) + _____ CO2 (g)
20. _____ Al (s) + _____ S8 (s) → _____ Al2S3 (s)

Answer: If it's balanced then you are right!

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2015: NAMING MOLECULAR COMPOUNDS

Naming Molecular Compounds Worksheet


Write the names of the following covalent compounds:

21)       SO3 __________________________________________

22)       N2S __________________________________________

23)       PH3 __________________________________________

24)       BF3 __________________________________________

25)       P2Br4 __________________________________________

26)       CO __________________________________________

27)       SiO2 __________________________________________

28)       SF6 __________________________________________

29)       NH3 __________________________________________

30)       NO2 __________________________________________


Write the formulas of the following covalent compounds:

31)       nitrogen trichloride __________________________________________

32)       boron carbide __________________________________________

33)       dinitrogen trioxide __________________________________________

34)       phosphorus pentafluoride ______________________________________

35)       methane __________________________________________

36)       sulfur dibromide __________________________________________

37)       diboron tetrahydride __________________________________________

38)       oxygen difluoride __________________________________________

39)       carbon disulfide __________________________________________

40)       nitrogen monoxide __________________________________________


Answers:


Write the names of the following covalent compounds:

21)      SO3                 sulfur trioxide

22)      N2S                 dinitrogen sulfide

23)      PH3                 phosphorus trihydride

24)      BF3                 boron trifluoride

25)      P2Br4               diphosphorus tetrabromide

26)      CO                  carbon monoxide

27)      SiO2                silicon dioxide

28)      SF6                 sulfur hexafluoride

29)      NH3                 ammonia

30)      NO2                 nitrogen dioxide


Write the formulas of the following covalent compounds:

31)      nitrogen trichloride                          NCl3

32)      boron carbide                                   BC

33)      dinitrogen trioxide                            N2O3

34)      phosphorus pentafluoride               PF5

35)      methane                                            CH4

36)      sulfur dibromide                               SBr2

37)      diboron tetrahydride                        B2H4

38)      oxygen difluoride                             OF2

39)      carbon disulfide                               CS2

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