A 0.8612 g sample of a mixture consisting of NaBr, NaI, and NaNO3 was analyzed by adding AgNO3 to precipitate the Br¡V and I¡V, yielding a 1.0186 g mixture of AgBr and AgI. The precipitate was then heated in a stream of Cl2, converting it to 0.7125 g of AgCl. Calculate the % (w/w) NaNO3 in the sample
Two equations in two unknowns. Solve simultaneously for X and Y.
Let X = mass NaBr
and Y = mass NaI
mm = molar mass
am = atomic mass
eqn 1:
X(mm AgBr/mm NaBr) + Y(mm AgI/NaI) = 1.0186
eqn 2:
X(2*mm AgCl/2*mm NaBr) + Y(2*mm AgCl/2* mm NaI) = 0.7125
Solve for X = NaBr and Y = NaI. Add these two masses, subtract from the sample mass which gives you the mass of NaNO3.
Then %NaNO3 = (g NaNO3/mass sample)*100 = ?
Post your work if you get stuck.
I am stuck on step 3. I don't know how to calculate.
I am assume there are 3 steps in calculates.
1. x+y+z = 0.8612
2. 0.009191x+ 0.0066716y= 1.0186
3. X(2*mm AgCl/2*mm NaBr) + Y(2*mm AgCl/2* mm NaI) = 0.7125
Thanks!
To determine the percentage (w/w) of NaNO3 in the sample, we need to calculate the mass of NaNO3 in the mixture and then divide it by the total mass of the sample.
1. First, calculate the mass of AgBr and AgI formed:
Mass of AgBr + AgI = 1.0186 g
2. Next, calculate the mass of AgCl formed:
Mass of AgCl = 0.7125 g
3. Since AgBr and AgI are formed by the reaction of AgNO3 with NaBr and NaI respectively, we can calculate the moles of AgBr and AgI using their molar masses:
Molar mass of AgBr = 187.77 g/mol
Molar mass of AgI = 234.77 g/mol
Moles of AgBr = (Mass of AgBr) / (Molar mass of AgBr)
Moles of AgI = (Mass of AgI) / (Molar mass of AgI)
4. Since AgBr and AgI are formed from NaBr and NaI in a 1:1 ratio, the moles of NaBr and NaI should be the same as the moles of AgBr and AgI, respectively.
5. Now we can calculate the total moles of NaBr and NaI in the mixture:
Moles of NaBr = Moles of AgBr
Moles of NaI = Moles of AgI
6. To determine the mass of NaNO3, we need to subtract the total moles of NaBr and NaI from the total moles of Na in the mixture.
7. The molar mass of Na is 22.99 g/mol. Calculate the total moles of Na:
Moles of Na = Moles of NaBr + Moles of NaI
8. Subtract the total moles of NaBr and NaI from the total moles of Na to get the moles of NaNO3:
Moles of NaNO3 = Moles of Na - (Moles of NaBr + Moles of NaI)
9. Finally, calculate the mass of NaNO3 using its molar mass (85.00 g/mol):
Mass of NaNO3 = (Moles of NaNO3) * (Molar mass of NaNO3)
10. Calculate the percentage (w/w) of NaNO3 in the sample:
% (w/w) NaNO3 = (Mass of NaNO3 / Total mass of sample) * 100
Note: Make sure to use the accurate molar masses and molecular formulas for AgBr, AgI, and NaNO3 in the calculations.
To calculate the percentage (w/w) of NaNO3 in the sample, you need to use the given information and perform a series of calculations. Here's how you can approach this problem:
1. Determine the amount of AgBr and AgI formed:
- The mass of the mixture of AgBr and AgI is given as 1.0186 g.
2. Convert the mass of AgBr and AgI to moles:
- Find the molar masses of AgBr and AgI.
- Divide the masses by their respective molar masses to obtain the number of moles.
3. Determine the moles of Cl2 reacted:
- Calculate the molar mass of AgCl.
- Divide the mass of AgCl formed (0.7125 g) by its molar mass to find the moles of AgCl.
4. Use stoichiometry to calculate the moles of AgBr and AgI:
- From the balanced chemical equation, you can determine the ratio of moles of AgBr and AgI to moles of AgCl.
5. Determine the moles of NaNO3:
- By subtracting the moles of AgBr and AgI from the total moles of the mixture, you can find the moles of NaNO3.
6. Convert the moles of NaNO3 to grams:
- Multiply the moles of NaNO3 by its molar mass to calculate the mass of NaNO3.
7. Calculate the percentage (w/w) of NaNO3 in the sample:
- Divide the mass of NaNO3 by the initial mass of the sample (0.8612 g) and multiply by 100 to obtain the percentage (w/w) of NaNO3.
By following these steps, you should be able to calculate the desired percentage (w/w) of NaNO3 in the sample.