hi, Im not sure how to explain this well but here goes.
Im doing a oxidization/reduction reaction to determine the charge of an element.
charge is n
formula n=a/b
Problem:
0.6215 g sample of nickle metal was dissovled in 100.0ml of fe 3+
Note for the formulas: I put all the charges in bracket cause i don't know how to make superscripts.
aFe(3+)(aq) +bNi(aq)--> aFe(2+)(aq) + bNi (+n) (aq)
15.00 ml sample of this solution was taken and titrated. If it took 26.48ml of 0.0200 M Cr2O7(2-)
Heres the other formula for dichromate
6fe(2+) + cr207 (2-)--->c + d
step 1) Find the moles Ni
= .6215 x mol/55.84= 1.06 x 10-2 mol
This is the part im having problems with. Since only 15 ml were used i did the following:
1.06 x 10-2 x 15.00/100.00= 1.59 x 10-2Ni
that gives me b
step 2)Now find the moles of fe
so i did the following:
26.48ml x 0.0200M x 6fe(2+)/1mol cr207(2-) x 1mol fe (3+)/1 mol fe(2+)
a= 3.18 x 10(2-) fe(3+)
step 3) finally, N=a/b
3.18 x10-2/1.59 x10-2=2
If it confuses you i can just simplify it to the part im having problems with.
Heres the simplified version:
I need to convert Ni to moles:
I have a 0.6215 g sample of Ni that was dissolved in 100.00ml of Fe 3+. Then, 15.00 ml of the sample was taken and titrated. It took 26.48 ml of .0200M Cr2072- to titrate the solution.
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I did the following to find the moles of Ni
0.6215g x M/58.69g=1.06 x 10-2 mol
1.06 x 10 -2 mol x 15.00 ml/100.00ml= 1.59 x 10-2 mol
thanks again dan
#1. I can't make out what you are trying to do. Some suggestions for future posts.
a. Type with i caps (as in I), Fe and not fe, Cr2O7 and not cr2O7.
b. For the charge on the ions, use the carat. Fe^3, Cr2O7^-2, Ni^+2, etc.
c. The atomic mass for Ni is not 55.84 but 58.69
d. Carry the division for moles Ni (0.6215/58.69 = 0.010595 which I would leave in the calculator as is but you have four significant figures and I would use them if I rounded to 0.01060.
e. Write the problem, THEN show how you solved it.
I only need help with step 3
We are trying to figure out the charge on Nickel. So we performed titrations.
First, 0.6215 g sample of nickle metal was dissovled in 100.0ml of Fe^3+.(acid based)
Then, 15.00 ml sample of this solution was taken and titrated. If it took 26.48ml of 0.0200M Cr2O7^2-
Step 1)
Find n
=using algebra i got the following
=aFe^3+(aq) +bNi(aq)--> aFe^2+(aq) + bNi ^n+(aq)
=3a + b0 for the reactants and 2a + bn for the reactants
=3a +b0 =2a +bn
solving for n.
=n=a/b
Step 2) Find the moles of Fe^ 3+
Fe^2+ = fe^3+ (from the formula above). Therefore, if we know Fe^2+ we know Fe^3+
Fe^2+ was titrated with dichromate. 26.48ml of 0.0200M Cr2O7^2 The formula is
6fe^2+ + cr207^2- = c + d
Theefore, 0.02648L x 0.0200M x 6mol Fe^2/1mol Cr2o7^2- x1 Mol Fe^3+/1 mol Fe^2+
= 3.18 x 10^-2 Mol Fe^3+
thats a
step 3)This is the part i'm having problems with. I need to find the moles of b. This is the moles of Nickel. I converted the grams of nickel to moles. Since we only used 15.00ml of 100.00 ml I wrote the following:
= 0.6215 g Ni x 1 mol/58.69g x 15.00 ml/100 ml
=1.59 x10-2 mol
step 4)
solve for n=a/b
3.18 x10^-2/1.59 x 10^-2
=2
So the charge on Nickel(for the products is 2. Then, i got to balance the equation.
Hope this helps. Thanks Dan
It seems like you're trying to determine the charge (n) of the element (nickel) in a redox reaction. Let's break down the steps and explain them in detail:
Step 1: Finding the moles of Ni (nickel)
To calculate the moles of nickel, you need the mass of the nickel sample and its molar mass. Given that the mass of the sample is 0.6215 g and the molar mass of nickel is 55.84 g/mol, you can use the formula: moles = mass/molar mass.
moles(Ni) = 0.6215 g / 55.84 g/mol ≈ 0.0111 mol
However, since only 15.00 ml of the solution containing nickel was used for titration (instead of the full 100.00 ml), you need to adjust the calculated moles accordingly.
moles(Ni used) = 0.0111 mol x (15.00 ml / 100.00 ml) ≈ 0.00167 mol
Therefore, the value of 'b' in the equation aFe(3+) + bNi → aFe(2+) + bNi(+n) is approximately 0.00167 mol.
Step 2: Finding the moles of Fe (iron)
To determine the moles of iron, you need the volume (in liters) of the solution containing iron, the molarity of the solution, and the stoichiometric coefficients from the balanced equation.
moles(Fe(3+)) = (26.48 ml) x (0.0200 mol/L) x (6 mol Fe(2+)/1 mol Cr2O7(2-)) x (1 mol Fe(3+)/1 mol Fe(2+))
Simplifying the calculation yields:
moles(Fe(3+)) ≈ 0.0318 mol
Hence, the value of 'a' in the equation aFe(3+) + bNi → aFe(2+) + bNi(+n) is approximately 0.0318 mol.
Step 3: Determining the charge (n)
Finally, you can determine the charge of nickel (n) by using the formula n = a/b:
n = 0.0318 mol / 0.00167 mol ≈ 19
Therefore, the charge of the nickel element in the reaction is approximately +19.
I hope this explanation helps clarify the steps and process for finding the charge of the element in this oxidation/reduction reaction. Let me know if you have further questions or need additional assistance!