weight vs. volume

[purplegirl]

Silly question. If I'm supposed to add 1oz of cal-hypo is that ounce in weight or volume?

[CarlD]

It's usually sold by weight.

If they want you to go by volume it's usually "1/4 cup".

[purplegirl]

thanks. that makes sense.

[AnnaK]

1 oz dry weight is 1/8 cup or 2 tblsp.

Here are some links to conversion charts:

http://www.exploratorium.edu/cooking...surements.html

http://www.foodgeeks.com/resources/conversion_charts#we see "Equivalents"

You can also use Google to do the conversion. In the search bar type: 1 oz = ? cups or any other conversion.

[waterbear]

1 oz dry weight is 1/8 cup or 2 tblsp.

This is not always true. particularly with pool chemicals that have different densities. It is a rough approximation at best but if you want to convert a weight measure to a volume measure you will need to do it separately for each item, based on it's density.
A pound of DE powder takes up a lot more space than a pound of trichlor tabs.
For example 1 tablespoon of steel ball bearings and 1 tablespoon of rice krispies each would weigh 1/2 oz by the formula above but we don't even need to measure and then weigh them to know this is not going to be true!

There is no hard and fast rule that will successfully convert a volume measurement to a weight measurement or vice versa.

However, an inexpensive kitchen or diet scale is excellent for weighing out pool chemicals.

[chem geek]

Examples of densities of some pool chemicals are in this thread where the second number (bulk) is the relevant one. You can see that densities vary from 0.837 for calcium chloride dihydrate to 1.44 for dry acid. The one ounce weight to one ounce (1/8th cup) volume approximation is only correct when the density is 0.959 g/ml.

Sorry for the bad formatting...the "CODE" formatting on this forum no longer works (that's used to force a fixed space font which is good for lining up columns).