If .40 l if water is added to the volume of cup 3, what would be the new molarity of a 2 m solution of kool-aid

0.7692 M ≅ 0.77 M.

Explanation:

(MV) before dilution = (MV) after dilution.

M before dilution = 2.0 M, V before dilution = 0.25 L.

M after dilution = ??? M, V after dilution = 0.25 L + 0.40 L = 0.65 L.

∴ M after dilution = (MV) before dilution/(V) after dilution = (2.0 M)(0.25 L)/(0.65 L) = 0.7692 M ≅ 0.77 M.

"you start with 15.67 g mgco3-xh2o, when heated and all the water is removed, you are left with 7.58 g mgco3 only.

therefore, you had 15.67 - 7.58 = 8.09g h2o  

moles of each :

7.58g mgco3 = ? moles = 7.58g / 83.4g/mole = 0.09moles  

8 09g h2o = ? moles = 8.09g / 18g/mole = 0.44moles  

molar ratio between the two by dividing both numbers by the smallest number :

0.09 / 0.09 = 1  

0.44 / 0.09 = 4.8  

mgco3-5h2o"