[Asoom]

I have 2 Q in my HW I can't solve them .
the first one I did not understand it ,the second I tried but I failed



1- An aqueous solution contains NaNO3 and KSCN . The thiocyanate ion is precipitate as AgSCN by addition of AgNO3 . After an excess of the precipitating reagent has been added .

a- What is the charge on the surface of the coagulated collidal?
b- What is the source of the charge ?
c- What ions make up the counter-ion layer?





2- A 0.7406 g sample of impure magnesite MgCO3 was decomposed with HCl; the liberated CO2 was collected on calcium oxide and found to weigh 0.1881g. Calculate the percentage of magnesium in the sample.

[Unknown008]

2.
Find the number of moles of carbon dioxide. (You have mass and relative mass)

Write the equation.

You'll find that one mole of CO2 is given off when 1 mole of Mg^2+ reacts.

So, you know the amount of Mg^2+ present.

Find the mass of that amount.

Then percentage purity is

[Asoom]

Thanks a lot. .

I did what you said and I get 14%

[Unknown008]

Yes, that's the answer! :)

I'm sorry for the first number, I haven't done that yet at school :o

[Asoom]

Yes, that's the answer! :)

I'm sorry for the first number, I haven't done that yet at school :o

That's oK. . You did what you have to. .

Thanks again. .