Homework Help: Concentration of a solution

1. Aug 17, 2015

caliban07

• You have to show your attempts, this is a forum policy. Also, all homework like questions should go to homework forum.
1 litre solution containing 28ml of glutaradehyde and the rest distilled water. What would be the concentration of glutaradehyde in solution in mg/l please.

2. Aug 17, 2015

Bystander

You have values for density and molecular mass of glutaraldehyde?

3. Aug 17, 2015

caliban07

Molecular mass is 100.1 g/mol and density is 1.06 g/ml

ThAnks

4. Aug 17, 2015

Bystander

You know what to do with those numbers?

5. Aug 17, 2015

caliban07

I sort of do with the help of Google. Not quite a maths or chemistry guru. I got an answer of 2.8ppm but I don't know if this is right. Was just trying to confirm and this seems to be the place to come.

Borek has been very helpful in the past.

6. Aug 17, 2015

Bystander

You've got a volume and a density; what can you do with those?

7. Aug 17, 2015

caliban07

Find the mass?

8. Aug 17, 2015

Bystander

Yes. What can you then do with that information?

9. Aug 17, 2015

caliban07

C=m/v

Although this is quite condescending it fun.

Mass = density x volume

= 1.06 x 1000ml = 1060grams ?

10. Aug 17, 2015

Bystander

Anything in particular you're trying to accomplish looking at the product of glutaraldehyde density and total solution volume?

11. Aug 17, 2015

caliban07

Well it can have quite harmful respiratory effects on humans if inhaled in only small amounts but people readily use it as a carbon source for aquatic plants in aquariums.

Metricide 14 is one particular brand which is 2.8% glut and the rest Distilled water. I have read studies that concentrations as little as 10ppm can equal LC50 24hrs. I'm trying to find out what concentrations people are adding depending on tank sizes to see if it can get anywhere near this number. Concentrations as low as 2.5ppm can harm inverts too.

12. Aug 17, 2015

caliban07

I meant 10ppm harmed particular species of fish and the same could apply in our aquariums.

13. Aug 17, 2015

caliban07

Am I on the right track by the way? Is that the correct answer for mass and if so what do I do with the answer and how do I convert the answer to mg/l?

Once I understand what I'm doing I should be ok in the future.

14. Aug 17, 2015

Bystander

No. That was the point of the question about your calculation of the product of glutaraldehyde density and total solution volume.

Let's take a different approach: how many milligrams in 28 grams?

15. Aug 17, 2015

caliban07

It doesn't matter. Thanks anyway.

16. Aug 18, 2015

caliban07

So if I use the density and volume to find the mass of the solute. I can then divide the solute mass by the total solution mass and multiply by 10^6 to find the concentration in ppm?

17. Aug 18, 2015

Bystander

Close enough.

18. Aug 18, 2015