Solutions

Welcome to our free

Chemistry Homework Help

forum.

Please read the forums rules before posting.

Find out how you can Help My Chemistry Tutor

[pumatied]

I need help on a problem:
Calculate the masses of the solids you must measure out to prepare 100 mL each of 0.025 M KNO₃, 0.025 M CuSO₄, and 0.025 M Ca(NO₃)₂. (Note that some of these salts are hydrates; their formulas are CuSO₄ 5H₂O and Ca(NO₃)₂ 4H₂O) You must include the waters of hydration when calculating the formula weights.

This is for a chem lab, and we haven't learned about waters of hydration in my lectures yet... Please help!

[Chemistry Tutor]

they really aren't that difficult

some salts form hydrates

so you probably learned about CuSO4

well if you went into the get this chemical out of the lab the label would not read but

CuSO4[dot]5H2O    where dot is a period floating in the middle

so when you do the calculations you have to add the molar mass of 5 water molecules to the mass of CuSO4

the hydrate isn't wet, the water molecules are just "trapped" in the crystal