What mass of Na2SO4 is needed to make 2.5L of a 2.0M solution?

Question

What mass of Na2SO4 is required to prepare 2.5 L of a 2.0 M solution? (Given: Na = 23 g/mol, S = 32 g/mol, O = 16 g/mol)
a. 178 g
b. 284 g
c. 356 g
d. 710 g  
Please explain how to solve this problem.

Anonymous · Accepted Answer

Na(2) = 46
S(1) = 32
O(4) = 64
that all adds up to 142 (this is the gFm, gram formula mass)
/ = divided by
M (molarity) = m (moles) / Liters (molarity formula)
2 = m / 2.5
moles = 5
(moles formula)
m = given mass / gram formula mass
5 = gm / 142
gm = 710  
Remember: capital M = molarity, lowercase m = moles

Doris Runolfsdottir · Answer

first find the molecular mass of your compound by adding together the mass of the constituents.
2 - Na  = 46amu
1 - S =  32amu
4 - O = 64amu
altogether = 142amu  
1 mole of anything weighs = # of amu's  in grams
so 142grams = 1 mole Na2SO4
you need 2mol per liter to make a 2.0 M (M= mol/L)solution
2M x 142g/L= 284g / per L for 2M
you have 2.5L so 
2.5L x 284g/L = 710g

Anonymous · Answer

710 g - novanet

Anonymous · Answer

here you have to prepare 2.0M solution into 2.5L volume.
the molarity required    2.0M
the volume to be made 2.5L
molarity definition: it is the number of moles of solute dissolved dissolved per litre of the solution.
the solute is Na2SO4.
one molar (1.0M) solution means one mole(one formula mass)of solute has been dissolved in one litre of the solution.
the formula mass is the sum of atomic masses of all the atoms present in that compound,
the formula mass of Na2SO4 =   2x Na + S +  4O
                                                = 2x23   + 32 +4 x16                                                 =142g/mole
if dissolve 142 g of above salt in one litre of water then it will give one molar solution,we require 2.0M so we need 2x142g salt per litre of the solution,
the total volume is 2.5 litre so totally we have to take 
5x142 g salt and dissolve in a suitable volume of water then make up to 2.5L
that would be   5 x 142g  = 710g
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Anonymous · Answer

g=grams of salt
mm=molar mass]
M=molarity
M=g/mm/L
2=g/mm/2.5
you put in the values!

Edwina Orn · Answer

how make .0094 na2so4

Anonymous

What mass of Na2SO4 is needed to make 2.5L of a 2.0M solution?

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