Molarity problem

[Opejay]

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What is the approximate molarity of a NaCI solution with
a specific gravity of 1.006?

A. 0.05M
B. 0.06M
C. 0.1 M
D. 0.2M

Thanks for your help.

 

[lunalight]

The answer is C.

If the specific graity is 1.006 that means the solution weighs 1.006kg, so there are 6g of NaCl in the solution. Convert 6g NaCl to moles (6g/60g/mol) is 0.1mol of NaCl. If there are 6g of NaCl, that means there is 1000g = 1L of water. So 0.1mol NaCl/1L water = 0.1M.

 

[Dreamer29]

Why wouldn't this calculation work?

1.006*1000kg * 10^-3m^3 * 1000g * 1mole =17 moles/L

Conceptually, what is that calculating?

 

[lunalight]

I think thats the calculation for water, not NaCl.

 

[Opejay]

The answer is C.

If the specific graity is 1.006 that means the solution weighs 1.006kg, so there are 6g of NaCl in the solution. Convert 6g NaCl to moles (6g/60g/mol) is 0.1mol of NaCl. If there are 6g of NaCl, that means there is 1000g = 1L of water. So 0.1mol NaCl/1L water = 0.1M.

How did you get 6g?

Thanks

 

[sciencebooks]

The answer is C.

If the specific graity is 1.006 that means the solution weighs 1.006kg, so there are 6g of NaCl in the solution. Convert 6g NaCl to moles (6g/60g/mol) is 0.1mol of NaCl. If there are 6g of NaCl, that means there is 1000g = 1L of water. So 0.1mol NaCl/1L water = 0.1M.

Could you explain where this comes from, please?`

 

[Raiden2012]

Could you explain where this comes from, please?`

density of water = 1g/cm^3

1000 g = 1000 cm^3 of water = 1 L

 

[sciencebooks]

density of water = 1g/cm^3

1000 g = 1000 cm^3 of water = 1 L

I'm sorry, I meant the 1000 grams part.

Lol, nevermind! 🙂 The 1000 grams is of the SOLVENT. Got it.