1 in 10,000 dilution for testing bleach %

[Abigail K]

For the 1 in 10,000 dilution to test bleach %, a 2-step serial dilution of 1 in 100 is indicated (i.e. a 1 in 100 followed by another 1 in 100).

I've noticed that the recommendation is add 10ml TO 1 litre water to achieve the 1 in 100 dilution.
Doesn't that result in a final volume of 1010ml and therefore a 1 in 101 dilution, rather than a 1 in 100 dilution?

Am I being pedantic?

 

[karmabiker]

Am I being pedantic?

Ummm. Yes.

In all seriousness - point well taken. A 1% margin of error is close enough for the types of calculations we do. Most of us are off by more than 1% regarding pool volume.

 

[JasonLion]

To be technically correct you want 990 ml of water, rather than 1000 ml, to add the 10 to. However it is considered impractical to measure 990 ml as distinct from 1000 ml, so the instructions were simplified. In any case, there are much larger sources of error later in the process. This one is not worth worrying about.

 

[bridgman]

I guess you could measure 1000 ml, then take 10ml out