Mass-Conc Stocih Q?

[luken93]

A sample of water was known to contain chloride
ions. To determine the concentration of chloride
ions in the water sample, a solution of silver
nitrate was added to 500 mL of the water. 1.26 g
of silver chloride precipitate formed. What was
the concentration of chloride ions in the water
sample?

Thanks

[Russ]

1) Write the reaction for silver nitrate and chloride ions in water
2) Calculate the number of mol of precipitate formed with n = m/M
3) Use the stoichiometric ratio to find the number of mol of chloride ions
4) c = n/V for the concentration (V = .5 because it's the original sample)

[luken93]

Hi, thanks for that, but can you just confirm step 1), because the way I've done it, the answer doesn't appear right?
Thanks

[Russ]

From memory should be: AgNO3 + Cl- ---> AgCl + NO3-

Unless I messed something up?

[andy456]

 
I don't think nitrate is needed because it is a spectator ion.
If you were to add it the equation would look like this:

[Russ]

Whether you write the ionic equation or not, the ratio is still the same.

Also, how do you do that fancy scientific notation?

[luken93]

No worries, I put Silver Chloride as AgCl2, therefore changing the molar mass 

[andy456]

ummmm I'm not very good at it but you just put [tex] at the beginning and end of what you want to write, and it makes it fancy....
you can also do hard mathematical symbols but theres a topic somewhere about that...
theres also a guide somewhere, i think its called latex

[akira88]

This thread really shouldn't be in the "Mid-year Exams Discussion" section

[luken93]

This thread really shouldn't be in the "Mid-year Exams Discussion" section

woops just realised haha, i just clicked on someones link I saw on updated topics
Sorry