I agree with some of what you have but not all of it. Here is your work.
.1g/100= .001g gold
I agree with 1E-3g Au
.001 g gold/ml * .5 ml = .00005 g gold
0.001 x 0.5 = 5E-4--you have 5E-5.
The rest of this I don't get. It appears to me that all of the Au you have at this point, and all the Au being used in the assay, is 5E-4g so the price to this point is 5E-4g x 380/33.8g = 5.62E-3 and I guess that is dollars.
I don't know where the 0.6 mL comes from and I don't follow the rest of your work; however, having said that I note that your answer is just a factor of 10 from my answer and that is a direct result of that first mistake above of 5E-5 for 5E-4. So I would think you did a good job but did a lot of extra work that wasn't needed.
.00005/.6ml = 8.33 *10^-5
8.33 *10^-5 * 100= 8.33 *10^-3 % w/v
.00005*1 troy ounce/33.8 g = 1.48*10^-6
1.48*10^-6 *$380 = $5.6*10^-4
One troy ounce of gold is worth $380. There are 33.8 grams per troy ounce. You have a stock colloidal solution of a very fine gold dust. Its concentration is .1% w/v. from this solution, 1 ml is placed in 9 ml of an isotonic, pH buffered solution to make a working stock. An assay calls for .5 ml of this working stock to which is added .1 ml of serum. What is the cost of hold used for each test?
My work is this and I am not sure if it is correct:
.1g/100= .001g gold
.001 g gold/ml * .5 ml = .00005 g gold
.00005/.6ml = 8.33 *10^-5
8.33 *10^-5 * 100= 8.33 *10^-3 % w/v
.00005*1 troy ounce/33.8 g = 1.48*10^-6
1.48*10^-6 *$380 = $5.6*10^-4
Any help would be greatly appreciated. Thanks!
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