Stoichiometry hydrated NiSO4 question

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Discussion Overview

The discussion revolves around stoichiometry calculations related to the empirical formulas of hydrated salts, specifically NiSO4 and MnSO4. Participants explore the calculations required to determine the mole ratios of the compounds and the water of hydration lost upon heating.

Discussion Character

  • Homework-related
  • Mathematical reasoning
  • Technical explanation

Main Points Raised

  • One participant calculates the moles of NiSO4 from a mass of 22.14g and finds a ratio that does not match the expected NiSO4.7H2O.
  • Another participant suggests a different calculation method for the moles of NiSO4, yielding a ratio of approximately 1:6.79, and questions the accuracy of their calculations.
  • A subsequent reply corrects the molar mass of NiSO4 provided by a participant, indicating that 150.76 g/mol is incorrect.
  • After recalculating with a corrected molar mass, a participant arrives at a ratio of approximately 1:7, supporting the formula NiSO4.7H2O.
  • A new question is posed regarding the empirical formula of MnSO4, with calculations leading to a proposed formula of MnSO4.4H2O.
  • Participants discuss the naming of the hydrate, with conflicting responses regarding the correct nomenclature for MnSO4.4H2O.

Areas of Agreement / Disagreement

There is no consensus on the naming of the manganese sulfate hydrate, as participants provide conflicting answers. The calculations for both NiSO4 and MnSO4 lead to different interpretations and results, indicating multiple competing views remain.

Contextual Notes

Participants express uncertainty regarding the accuracy of their calculations and the correct molar masses. There are unresolved questions about the naming conventions for hydrates, which depend on the definitions used.

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Homework Statement



given that 40.14g sample of hydrated NiSO4 is reduced in mass to 22.14g upon heating.
Show that the formula of the hydrate is NiSO4.7H20

Homework Equations



n / M

The Attempt at a Solution



22.14g/ 40.14g = 0.5516 (mol of NiSO4)

40.14g - 22.14 = (18 g H20 lost in heating)

18.0 / 18.02 = 0.9989 (mol of H20)

∴ mole ratio = 0.5516 : 0.9989

but this does not give the result in the ratios of 1:7 (NiSO4.7H20)stoichiometry (or chem for that matter) isn't really my thing and I have about 10 questions similar to this, can someone please point me in the right direction please?
 
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22.14/ 150.76 = 0.1469 (mols of NiSO4)

0.1469:0.9989
1.469:9.989 (x10)

which is a ratio of 1:6.79

but is there a more accurate way of calculating this?
 
Your second calculation is much better than the first. Have another try at calculating the molar mass of NiSO4. 150.76 g/mol is wrong.
 
thanks for the tip johnRC, I needed to check my copy of the periodic table better!

does this calculation look more correct? the ratios are almost perfect, which my chem teacher has said is to be expected.

22.14 / 154.76 = 0.14306 (mols of NiSO4)
40.14g - 22.14 = 18.00 (H20 lost in heating)
18.0 / 18.02 = 0.9989 (mols of H20)
0.14306:0.9989
0.14306/0.9989 = 0.1432
1/0.1432 = 6.982

1:6.982
6.98 ≈ 7
∴ NiSO4.7H2O
 
Right on, symmetrica1!
 
thanks john!

could anyone take a look at this for me please?

Given that a 139.4g sample of hydrated MnSO4 is reduced in mass to 94.38g upon heating, find the empirical formula of the Hydrate. Also, write the name of the hydrate of manganese sulphate.

94.38g / 151g = 0.6250 (mols of MnSO4)
139.4g – 94.38g = 45.02g (H2O lost in heating)
45.02 / 18.02 = 2.4983 (mols of H2O)

0.6250:2.4983
0.6250/2.4983 = 0.250166
1 / 0.250166 = 3.997

1:3.997
3.997 ≈ 4
∴ MnSO4.4H2O

would the name of the hydrate be Manganese (II) sulfate monohydrate?
 
Last edited:
5ymmetrica1 said:
MnSO4.4H2O

Yes.

would the name of the hydrate be Manganese (II) sulfate monohydrate?

No.

Mono means one, not four.

Please start new threads if you have new questions.
 
sorry borek, I thought it would come under the same topic heading anyway so was just trying to keep your forums neat. Will do in future posts

thanks for checking my answer
 

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