how many grams of soild mognesium chloride, MgCl2, need to be used to make 250 ml of 0.50Msolution?

Question

how many grams of soild mognesium chloride, MgCl2, need to be used to make 250 ml of 0.50Msolution?

(MgCl2 molr mass=95.21)

the asnwer is 12 g
but how would you solve this?

Answer 1

Mr of MgCl2 = 95.21

0.5M requires 95.21/2 amt of solid and 1 litre of water
= 47.605g of solid
In 250ml = 47.605/4
= 11.9g
= 12g (round to 2 sf)

Answer 2

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Answer 3

First, you calculate the number of moles of magnesium chloride in the solution, which is number of *liters* of solution, times the molarity:

(250 mL) x (1 L / 1000 mL) x (0.50 mol / L) = 0.125 mol

Then multiply the number of moles by the molar mass of magnesium chloride to get the number of grams needed:

(0.125 mol) x (95.21 g / mol) = 11.9 g MgCl2

Answer 4

n = M. v

the amount of moles is : 250 . 0.5 = 125mmoles

mass = moles x Molar mass
= 125 . 95.21
= 11901.25 milligrams
=12grams