how do you convert to grams???????

Question

What mass of solute is needed to make 210 mL of a 0.663 M MgF2 solution

how do i do this???????????
step by step

Answer 1

you want 0.663 moles/litre of MgF2.

Molecular weight of MgF2 = 24.3 + 2x19 = 62.3 g

0.663 moles MgF2 = m/MW = m/62.3
m = 0.663*62.3 = 41.3 g (g in one litre)

In 210 mL (0.21L) you will have 0.21*41.3 g of MgF2 = 8.7 g

Tricky tricky: The question is asking for the wieght of the solute, which is the stuff that gets dissolved in the solvent. The solute is the MgF2, so the answer is 8.7 g of MgF2.

Answer 2

first you need to know a few things
molarity (M)= # of moles/ volume in Liters

MgF2 has a molar mass of 62.30 g

you know molarity and volume so you find the number of moles and convert that into grams

.663M x .210L =.139mol

.139mol x 62.30g/1mol= 8.66g

Answer 3

Alright, M stands for molarity, or moles per liter. If you were to multiply this value by your volume (in liters), then you would know how many moles you need.
So:
(.663 mol/L)*(.210L)=.13923 mol MgF2

Then, you multiply this by your molar mass (62.31 g/mol).

(.13923 mol)*(62.31 g/mol)=8.68 grams MgF2

Hope that helps.

Answer 4

you either multiply or divide.