Question: Calculate the solubility (g/L) of CuBr at 25 degrees celsius in 0.0110 M CoBr2. Ksp of CuBr = 5.3*10^-9.
I am capable of doing it in pure water, but I am struggling with how the two bromines in CoBr2 will affect the answer and ICE TABLE set up.
Thank you!
Follow up work:
CuBr --> Cu + Br
CoBr2 --> Co + 2 Br
Set up for solubility in pure water:
5.3*10^-9 = x^2
x= 1.5 g/L
Set up (?) for solubility in 0.011 M CoBr2:
5.3*10^-9 = (x)(0.022+x)
Sorry: for solubility in water x multiplied by the molar mass equals 1.5 g/L
Your set up is right.
This is a common ion problem and the effect of the CoBr2 (Br is the common ion) DECREASES the solubility of CuBr as you would predict from LeChatelier's Principle.
CoBr2 is a soluble salt and dissociates at 100% to CoBr2 --> Co^2+ + 2Br^-
..........0.0110..0.0110....0.0220
Then for the CuBr we have
..........CuBr --> Cu^+ + Br^-
I.........solid....0......0.0220
C.........solid....x........x
E.........solid....x.....0.0220+x
Ksp CuBr = (Cu^+)(Br^-)
5.3E-9 = (x)(0.0220+x)
If you assume 0.0220 + x = 0.0220 (which is true if x is small and it is), then solve for x = (Cu^+) = (CuBr) in mols/L. Then convert to grams/L.
When you finish conmpare that to the solubility of the CuBr you worked out in pure water and see that the solubility decreased. Then look at the equation and see that you could predict that from LeChatelier's Principle.
Thank so much Dr. Bob!!
X-RAY DIFFRACTION OF AN UNKNOWN METAL, MIGHT BE DANGEROUS (10/10 points)
Last week you and a friend started an experiment to obtain the X-ray diffraction peaks of an unknown metal. Through these diffraction peaks you wanted to determine:
(a) whether the cell is SC, BCC, or FCC
(b) the (hkl) value of the peaks
(c) the lattice parameter a of the metal
Unfortunately, however, your friend (since he's not in 3.091) left MIT yesterday, not to return until next semester. All of the data that you could recover from the rubble in his room was the following:
[mathjaxinline] sin^2(\theta) [/mathjaxinline] 0.120 0.239 0.480 0.600 0.721 0.841 0.956
You also know that the metal is in the cubic crystal system and the wavelength of the X-rays used is [mathjaxinline] \lambda_{CuK_{\alpha}} [/mathjaxinline]. Using the following information, determine the information you were originally interested in (a, b, and c above).
a. Is the cell SC, BCC, or FCC?
SC<text>SC</text> - correctFCCBCC
b. Enter the hkl value of the peaks as a list separated by commas. Do not put spaces between the values. For instance:
[mathjaxinline] \theta_1,\theta_2,... = (100),(111),... [/mathjaxinline]
(100),(110),(111),(200),(102),(112),(202) - correct
c. Enter the lattice parameter a in Angstroms.
2.24 - correct
Ma chakka muji randi ko choro ho
To calculate the solubility of CuBr in the presence of CoBr2, you need to consider the common ion effect. The CoBr2 will provide additional bromide ions (Br-) to the solution, which will affect the solubility of CuBr.
To solve this problem, you will need to set up an ICE table and use the Ksp expression for the solubility equilibrium. Here's how you can approach it step by step:
1. Write the balanced equation for the dissociation of CuBr:
CuBr (s) ⇌ Cu+ (aq) + Br- (aq)
2. Write the expression for the solubility product constant (Ksp):
Ksp = [Cu+][Br-]
3. Identify the changes in concentration of the ions in the equilibrium expression. Let's assume that 'x' is the solubility of CuBr in moles per liter.
4. Set up the ICE table for the equilibrium:
CuBr (s) ⇌ Cu+ (aq) + Br- (aq)
Initial: x 0 0
Change: -x +x +x
Equilibrium: x x x
5. Substitute these values into the Ksp expression:
Ksp = [Cu+][Br-] = x * x
6. Consider the effect of CoBr2. Since it dissociates as:
CoBr2 (s) ⇌ Co2+ (aq) + 2Br- (aq)
The concentration of Br- ions will be increased by the presence of CoBr2. In this case, it is given that the concentration of CoBr2 is 0.0110 M.
7. Now, you need to consider the concentration of Br- ions due to the CuBr dissociation and the additional Br- ions from CoBr2. The total concentration of Br- ions will be x + 2(0.0110 M) since there are two Br- ions in CoBr2.
8. Substitute the expression for the total concentration of Br- ions in the equilibrium into the Ksp expression:
Ksp = (x)(x + 2(0.0110 M)) = x^2 + 0.0220x
9. Substitute the given Ksp value and solve the quadratic equation using the quadratic formula:
5.3*10^-9 = x^2 + 0.0220x
10. Solve the equation to find the value of x, which represents the solubility of CuBr in the presence of CoBr2.
Once you find the value of x, you can convert it to grams per liter (g/L) by multiplying by the molar mass of CuBr.
Remember to always double-check your calculations and units to ensure accuracy.