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1. Calculate how much Zn(NO3)2 · 6H2O (in grams) is needed to prepare 0.5L of 1000 mg Zn/ L solution knowing the following data: Molar mass of Zn is 65.38 g/molMolar mass of Zn(NO3)2 · 6H2O is 297.49 g /mol.Your answer must be given with 3 digits, for example X.YZ g

2. (Original post by steffff)
Calculate how much Zn(NO3)2 · 6H2O (in grams) is needed to prepare 0.5L of 1000 mg Zn/ L solution knowing the following data: Molar mass of Zn is 65.38 g/molMolar mass of Zn(NO3)2 · 6H2O is 297.49 g /mol.Your answer must be given with 3 digits, for example X.YZ g

Work out:

1) Mass of zinc you need for 0.5L
2) Number of moles of zinc that equates to. this will be the number of moles of hydrated compound needed.
3) Mass of hydrated salt needed.

All done with moles = mass / Mr (or Ar)
I understand how to obtain the mass at the end from the formula, however I dont understand how to get the moles from the 0.5L of 1000mg Zn/L?
4. (Original post by steffff)
I understand how to obtain the mass at the end from the formula, however I dont understand how to get the moles from the 0.5L of 1000mg Zn/L?
If 1L contains 1000mg (1g) how much does 0.5L contain?

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