molarity problem

[inaccensa]

What is the approximate molarity of a NaCI solution with
a specific gravity of 1.006?
A. 0.05M
B. O.06M
C. 0.1 M
D. 0.2M

S.G. = D NaCl/D H20

DNaCl = 1.006*1000kg * 10^-3m^3 * 1000g * 1mole =17 moles/L
11111 1 m^3 111111111L 1111111 1kg 1111 58g

What am I doing wrong?

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[Omni]

Specific gravity is a ratio of the density of substance to the density of water.
Since density of water is just 1.0, density of the substance is 1.006.
Multiply that with the volume (1 L) and you will get 1.006 kg.

This 1.006 kg is the mass of the NaCL AND the water.
1 L of just plain water is just 1.0 Kg and 1 L of NaCL + water is 1.006Kg, the difference of the two will give you the mass of the NaCl alone, which is 0.006 kg=0.006g


So with 6g of NaCl, you end with ~0.1 mole of NaCl which translates to ~0.1 M.