What is the mass of NH3 per cc in a solution of ammonia gas passed into water?

[Prashasti]

Ammonia gas is passed into water, yielding a solution of density 0.93 g/cm^3 and containing 18.6% NH3 by weight. The mass of NH3 per cc of the solution is
1) 0.17
2) 0.51
3) 0.34
4) 0.68I solved it using the molarity equation.

Molarity = 10xd/MM

where,

x - % by weight
d - density
MM - Molar mass

And then I multiplied molarity with Molar mass (17 g mol^-1) and got 172.98 as the answer, whereas the answer is 0.17.

Where did I go wrong?

 

[Borek]

Molarity = 10xd/MM

Here.

First, this equation is wrong as written, second, even in the correct form it is not universal - it works only in specific situations. Do you know what they are?

 

[Prashasti]

No. I'm in high school. So, I don't know much about that. What specific situations are you talking about? .

Here.

First, this equation is wrong as written, second, even in the correct form it is not universal - it works only in specific situations. Do you know what they are?

 

[Borek]

You were given this equation without any explanation?

 

[theodoros.mihos]

Let $x,y$ the number of moles in a cc. Writing the problem we have:
$$ \frac{17x}{17x+18y} = 0.186\times 0.93 $$

 

[Borek]

Let $x,y$ the number of moles in a cc. Writing the problem we have:
$$ \frac{17x}{17x+18y} = 0.186\times 0.93 $$

Perfect way of overcomplicating things. How you are going to solve one equation with two unknowns?

 

[epenguin]

Forget about molarity which doesn't enter into his simple arithmetical problem.

Even forget about the density - it's not a million miles away from 1 g/cc.

Then only one of the given answers is anywhere near anything you would expect.

Though once you have seen which it is, do the working out of the exact answer.

 

[mooncrater]

HINT:
MOLARITY is the number of moler PER LITRE of solution. Whereas you are asked the mass of NH₃ in millilitres (or cc).