Question

how many grams of sodium chloride are there in 2.5 L of a 0.4% w/v solution?. need to know how to figure this out

Answer 1

I get one gram..but I thimk I am doing this wrong

Answer 2

0.4% w/v solution = .4 grams of sodium chloride per 100mL of solution

.4g/[(100/1000)L] = ?g/(2.5L)

I divided 100 by 1000 to get liters. Cross multiply and solve for the number of grams of sodium chloride.

This will give you a better sense of percentage by weight:
http://www.sciencecompany.com/lab/test_solns.htm

Answer 3

so I would set it up like

4g ?
---- -----
10L 2.5L

so i did 4 x 2.5 = 10 / 10 = 1 gr. is this right?

Answer 4

the numerator was supposed to be 0.4 g

the 10L denominator you computed is incorrect, 100/1000 = .1 L

Instead you'll have this when you cross multiply:

(0.4g)*(2.5L)=(?g)(.1 L)

Answer 5

Oh, so now I have 0.016 grams. I think I got it now..thanks :)