Talk:Specific gravity

See the current discussion at Talk:Relative density regarding merging. Vsmith (talk) 00:38, 23 October 2010 (UTC)

NOTE: As of October 2010, the article content for specific gravity has been moved to the article relative density; until specific gravity is reinstated as a separate article, discussion comments should be added to the discussion page for relative density instead of this discussion page. (copied from that discussion page:)

:The content from specific gravity has been merged into this article, and some distinctions have been made to try and point out the subtle differences between the terms. That is that SG has a reference density as water, while relative density is more general. Please feel free to expand on this. +mwtoews 20:59, 14 February 2007 (UTC)

[Please remove or move this header-comment if/when [issue is resolved.]

--Header Comment ; last modified 23 October, 2010 (modified by Vsmith (talk) 00:38, 23 October 2010 (UTC))

Discussion for article Specific gravity

Notation (2008)

I am not a scientist, but i believe the density of water should be 1000kg/m3, not 1000kg/m-3 as stated on this page. hopefully someone more qualified will edit the page so that readers are not confused. apologies if i'm wrong -- i checked other web pages. Ejj357 (talk) 20:55, 29 March 2008 (UTC)ejj357

Actually, u quoted it wrongly.

1000 kg·m⁻³ is what is in the article. The '.' kindoff refers to * so its really 1000kg*m⁻³ which would read 1000kg per cubic meter. ie: its correct, nothing wrong with it. Thx for the headsup!--Venny85 Venny85 21:05, 29 March 2008 (UTC)

More specifically: 1000 kg·m⁻³ = 1000 kg/m³. Both are correct. +mt 23:30, 29 March 2008 (UTC)

Both the "density" and "relative density" articles use kg/m³, not kg·m⁻³. For consistency, we should consider using the same style. --TimAgen (talk) 20:51, 1 July 2008 (UTC)

Discouragement of specific gravity?

About the use of specific gravity being discouraged in tecnical use. I am aware the use of specific gravity in the everyday world and still taught, as a scientist who tries to reduce ambiguity in my work, I see it necessary to include this in the article because of the importance of the particular issue...in the reference for example references itself to publications from IUPAC (1993) and ISO standards Handbook 2 (1992) and the reference clearly states in the definition that the term is now discouraged. I was trying to make it clear that in a technical sense that actual density should be used because specific gravity is usually calculated or determined by buoyancy concept for example. It also a known fact that the density of water is neither constant (see VSMOW) nor has a "true" density of 1000 kg/m3. I am just trying to keep truth and up to date information so others can have a better view of the term. —Preceding unsigned comment added by Jmmeadows (talk • contribs) 03:59, 15 April 2008 (UTC)

I figured the relation would be best located next to initial sentence of the entry. Sorry about that.

Actually, thats not really true. Specific gravity is used in many technical and operational instances. It is used to calculate API gravity in oils, viscosity unit conversions, grading of various petroleum products, calculation of ship loading capacities etc etc. It is a very commonly used number in the real world, definitely not discouraged in any way. You mention that specific gravity is not used in any scientific field requiring high precision, however, specific gravity wasnt meant to be a scientific term, but rather a working, practical term with real uses. It wasnt coined as a synonym of sort with scientific terms like density. ie: specific gravity is a kindoff borrowed industrial term never meant for use in scientific measurements. Not because 'density of water is neither constant' (most substances have densities that vary with temperature), and "true" density is never mentioned but density is always mentioned with a temperature attached eg: 1000kg/m3 @ 4C. The next line after you inserted your text clearly defines the term used scientifically: 'synonymous with, relative density, with the latter term often preferred in modern scientific writing.' This line clearly differentiates the uses of the various terms in different fields in different contexts. Venny85 (talk) 17:02, 15 April 2008 (UTC)

I see exactly where your coming from, in many cases most references commonly state water's reference density as being "exactly" 1000 kg/m3 (I see that too often). When your dealing with 4 to 5 signifigant figures, I agree with you for sure. Over the years I've seen many times where specific gravity is used in formulations for calculating the mass of solute from mass percent and specific gravity, sure it is fine when for a reasonable approximation, but in the instance of diluting a concentrated acid for instance, it is strongly recommended instead of using a volume of acid that it is measured by mass. And in the article of relative density, it is clearly a "relative" density, not true density and the relative reference material must be striclty adhered to. Most assume that water is the same all over the globe (isotopic composition), most do not take that into account, you see where I'm coming from? But in any case as long as the refernces are made clear than sure it is ok depending on how deep they wanna go. Anyways have nice day and thanks for talking because everyones input is important because they do like to change the rules on us and can lead to many differentiating opinions, which is what helps us tomorrow and so on.

Density not weight?

I changed denser back to heavier because heavier is a concept that is easier to understand and because both statements are equally true. So why was it changed back to denser with the statement "density not weight"? Thanks. Mmyotis ^{^^o^^} 15:12, 28 May 2008 (UTC)

Ahh, never mind. I suppose it should read heavier (per unit volume), which is just a complicated way of saying denser. Mmyotis ^{^^o^^} 15:17, 28 May 2008 (UTC)

Well your not too far off the mark. See specific weight. It's just awkward to say "higher specific weight" then is is to say "higher density". Also g is constant for specific gravity, so it is simpler to use density for the higher/lower comparison. I'd hope if a reader were reading this article they would have grasped the physical concept of density. +mt 17:19, 28 May 2008 (UTC)

Gases

The lead in needs to be more vauge. Gases usually have a refence substance of air at 20oC (293.15 K, 68oF) and 1 atm. I started to change it, but wasn't sure I wasn't sure how to divide it up yet. As the leadin is too specific, its hard to change without breaking the article without making an overhaul. Pirate^Argh!!1! 23:33, 15 January 2009 (UTC)

This is an article that is for the relative density of materials with water as a reference. You might want to look at the relative density article for the general subject (including gas references), which I'm guessing is what you are after. +mt 05:05, 16 January 2009 (UTC)

My chemical engineering textbook had specific gravity defined more loosely and gases were considered as well ( usually compared to air ). Regardless, I'm fairly certain that specific gravity should not be limited to water as a reference substance. Pirate^Argh!!1! 14:52, 18 January 2009 (UTC)

Some time ago there was consensus among editors that the topic of this article would discuss the relative density using water as a reference (since this is the most common use) and the relative density article would discuss the generic case that your textbook discusses. Concepts have different names from one textbook to another, so your textbook is correct, but what it calls "specific gravity" is really relative density on Wikipedia. I've been thinking about making this distinction clear at the top, maybe I'll add it now. +mt 20:05, 18 January 2009 (UTC)

SG x 1000 (2009 Jun)

I agree that a citation is needed and I am looking for one. There is also a mention of SG x 1000 in the Baumé scale article and this is linked to Gravity (alcoholic beverage) but I can find no mention of SG x 1000 in that article. Biscuittin (talk) 09:27, 16 June 2009 (UTC)

Removal of Sp. Gr. Article Contested (2010 Aug)

I don't know why [the page specific gravity] was set as a redirect, but it shouldn't have been. It's linked to on a large portion (if not most) of the pages for various substances, since their specific gravity is listed instead of, not in addition to, their measured/calculated density- Chakradragon (talk) 22:04, 19 August 2010 (UTC)

Agreed. Removal of the specific gravity page was a poor decision. Feel free to re-create the article specific gravity; just coordinate content with the other article when you do so. --Libertas (talk) 20:14, 6 October 2010 (UTC)

I agree and have returned the article. --Kevin Murray (talk) 22:28, 6 October 2010 (UTC)

What is the relation betwn Volume, SG & Weight??

What is the relation betwn Volume, SG & Weight —Preceding unsigned comment added by 117.205.177.133 (talk) 08:30, 17 January 2011 (UTC)

Pure decent 80 proof Vodka has a Specific gravity of 0.9496. Put a measuring container on scale and set to zero/tare so only contents are weighed. Add 100ml of Vodka, my scale shows 97 grams (should show 95grams), (water is 101 Grams per 100mL) but it's a cheap scale. Specific gravity is density compared to density of water, so there aren't units. A table of specific gravities is useful if you want to make layered drinks, for example. I'll add the Cocktail Specific Gravity List as a reference. Gotta make it fun. ☺ 8r455 (talk) 00:32, 9 August 2017 (UTC)

True specific gravity formula

The formula for true specific gravity must express symbolically the definition stated in the previous paragraph. It would be more convenient to re-use in a third line some of the mathematical steps to show that true specific gravity can be computed from different properties. I will be bold and do it.George Rodney Maruri Game (talk) 20:41, 17 January 2011 (UTC)

The Examples page is a mess

Examples are given in three styles. It does not say what the base substance is (and it apparently changes from air to water part-way through). OrangeDog (τ • ε) 13:13, 12 February 2018 (UTC)