# Simple dimensional analysis problem, thanks for any help

• sp3sp2sp

## Homework Statement

It requires 10 microliters of a Cu(NO_3)_2 solution to produce a spot of 1cm in diameter. If the Cu(NO_3)_2 solution contains about 6g Cu^2+ per liter, then how many micrograms of Cu^2+ ions are there in one spot?

## Homework Equations

simple dimensional analysis problem:
1st conversion factor is 10^6micrograms / 1g = 1
2nd conversion factor is 10^6 microliters/1L = 1
also please note that u = mu symbol

## The Attempt at a Solution

6g/L * 10^6ug/1g * 1L/10^6uL = 6ug/uL

problem states that 10uL of solution required to make one spot, so multiply 6ug/uL by factor of 10 = 60 ug/uL

It doesn't look right to me but I don't know why. Thanks for any help

## Answers and Replies

You need to multiply by 10 microliters/spot, not just by 10. In this type of dimensional analysis, you multiply the original item by factors/fractions that are always equal to 1. ## \\ ## The answer you get is not 60 micrograms per microliter=that is incorrect, (you calculated that it is 6 micrograms/microliter=that is correct and it doesn't change), Edit: I'll let you compute what the answer should be, given these inputs...

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