You have a stock solution consisting of 2.5l of 6.00m mgso4. however, you need 225 ml of a 0.500 m solution. how will you dilute the solution, and how much of the stock solution will you need?
a) 20.0 ml (not the answer)
b) 9 ml
c) 18.8 ml
d) 23.08 ml

18.8 mL

Explanation:

The dilution formula states that the product between the initial molarity and the initial volume should be equal to the product between the final molarity and the final volume, since the number of moles of a substance remains constant in a dilution process:

We are given the initial molarity of the stock solution , the final molarity of the diluted solution and the final volume of the diluted solution .

Rearranging the expression for the volume of the stock solution, we get:

Therefore, 18.8 mL of the stock solution are required.

"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"