# [SOLVED] Density of a substance

• Jun 1st 2010, 04:01 PM
Intrusion
[SOLVED] Density of a substance
A calibrated flask was filled to the 25.00 ml mark with ethyl alcohol. By weighing the flask before and after adding the alcohol, it was determined that the flask contained 19.7325 g of alcohol. In a second experiment, 25.2060 g of metal beads were added to the flask, and the flask was again filled to the 25.00 ml mark with ethyl alcohol. The total mass of the metal plus alcohol in the flask was determined to be 39.2184 g. What is the density of the metal in g/ml?

I've tried doing D= M/V and doing 25.2060/25 - 1.00824, but that is wrong.
I've also tried first getting the entire density 39.2184/25 = 1.568736 and subtracting the density of the alcohol alone (19.7325/25 = .7893): 1.568736 - .7893 = .779436 g/mL

This was also wrong. How is this problem done? Thanks
• Jun 1st 2010, 04:53 PM
skeeter
Quote:

Originally Posted by Intrusion
A calibrated flask was filled to the 25.00 ml mark with ethyl alcohol. By weighing the flask before and after adding the alcohol, it was determined that the flask contained 19.7325 g of alcohol. In a second experiment, 25.2060 g of metal beads were added to the flask, and the flask was again filled to the 25.00 ml mark with ethyl alcohol. The total mass of the metal plus alcohol in the flask was determined to be 39.2184 g. What is the density of the metal in g/ml?

I've tried doing D= M/V and doing 25.2060/25 - 1.00824, but that is wrong.
I've also tried first getting the entire density 39.2184/25 = 1.568736 and subtracting the density of the alcohol alone (19.7325/25 = .7893): 1.568736 - .7893 = .779436 g/mL

This was also wrong. How is this problem done? Thanks

alcohol density ... $\displaystyle \frac{19.7325}{25.00} = 0.7893$ g/ml

$\displaystyle m_a = 39.2814 - 25.2060 = 14.0754$ g
that mass of alcohol will occupy $\displaystyle V = \frac{14.0754}{0.7893} = 17.8328$ ml
that leaves $\displaystyle 7.1672$ ml of volume left for the beads ...
bead density = $\displaystyle \frac{25.2060}{7.1672} = 3.5168$ g/ml