Opioids heroin displacing water

[Swimmingdancer]

EDIT: Strange, I didn't see all the posts before I made this post and thought a bunch had dissapeared in the merge.

I'm confused, before these 2 threads were merged I thought someone said that the volume should not increase if you are adding something soluble to water and that it must be the cuts? Was that incorrect? I did notice the volume would increase for me when I added heroin to water and I always just assumed it was because you were adding the volume of the heroin to the volume of the water (although the increase wouldn't be as much as the volume of the heroin when dry, which makes sense). When there was not a volume increase, or there was a volume decrease, I had assumed that was just from part of the water evaporating if a person cooked it, or from not getting all the liquid out of the filter. But the volume increase in my case was noticeable, and it doesn't totally make sense though because even if dissolving something should not increase the volume by a noticeable amount, I don't see how it could have been due to insoluble cuts, since I was still making a solution which was completely clear, so...

EDIT: ninja'd by pyro and bronson. Can anyone confirm which is true? Should dissolving heroin in water increase the volume of water or leave it the same? Later edit: I think volume changes would depend on the substance.

 

[Dobe]

As somewhat mentioned by effie, if something is fully dissolved then it will fit in between the molecules thus not adding any volume.

Additional volume = non-dissolved substances

Can anyone refute this?

 

[Mass08]

Old post but I've been finding mixed opinions online.

I believe Pyro is correct though, this supports that idea.
http://www.bbc.co.uk/learningzone/clips/mass-and-volume-changes-during-dissolving/1883.html

 

[The.Ghost]

Not quoting anyone directly, but my understanding is that volume of water + mass of powder does not necessarily equate to increased volume. Increased mass / density of solution for sure, but not necessarily volume. Doesn't dissolution mean you could actually get less volume from given vol + given mass in a properly dissolved solution?

Correct. I can't find a source at the moment, but if you take a volume of solvent and add a solute, the volume of the final solution may be more or less than the combined volumes of the solvent and solute. There isn't a clear-cut correlation. For an example of the latter, remember the old alcohol + water demo where 10 mL of each mixed will give you less than 20 mL of solution. As a more extreme example, if you start with, say 100 mL of pure water and add some sodium hydroxide, the volume of the final solution will actually be less than 100 mL.

 

[Swimmingdancer]

Correct. I can't find a source at the moment, but if you take a volume of solvent and add a solute, the volume of the final solution may be more or less than the combined volumes of the solvent and solute. There isn't a clear-cut correlation. For an example of the latter, remember the old alcohol + water demo where 10 mL of each mixed will give you less than 20 mL of solution. As a more extreme example, if you start with, say 100 mL of pure water and add some sodium hydroxide, the volume of the final solution will actually be less than 100 mL.

Yeah, I was going to say the same thing, that it depends on the substance one is dissolving in the water. Unfortunately - unsurprisingly - there isn't much info on whether or not heroin should add or subtract from volume when dissolved in water.

 

[down508]

35 ml sounds like a giant shot. are you sure you dont mean .35 ml

 

[Dobe]

Unfortunately - unsurprisingly - there isn't much info on whether or not heroin should add or subtract from volume when dissolved in water.

White heroin is a salt and the solubility is similar (1g in 1.6 ml) so it shouldn't be too different from table salt.

"When sodium chloride dissolves in water to make a saturated solution there is a 2.5 per cent reduction in volume."

 

[Mr.Scagnattie]

White heroin is a salt and the solubility is similar (1g in 1.6 ml) so it shouldn't be too different from table salt.

"When sodium chloride dissolves in water to make a saturated solution there is a 2.5 per cent reduction in volume."

Yeah, pure heroin is incredibly water soluble.

 

[Swimmingdancer]

White heroin is a salt and the solubility is similar (1g in 1.6 ml) so it shouldn't be too different from table salt.

"When sodium chloride dissolves in water to make a saturated solution there is a 2.5 per cent reduction in volume."

2.5% would be imperceptible in small quantities with normal measuring devices.

Chemistry is not my strongest subject, but I don't think we can assume that all salts have similar properties regarding volume when added to water. Furthermore, volume is not constant, it changes depending on temperature right? So if adding something changes the temperature (or a person is heating their heroin + water) then that would make a difference too right? I'm pretty sure adding sodium chloride to water lowers the temperature?

Anyway, I'm sure someone other than me can figure this out using the Molecular Weight of diacetylmorphine hydrochloride: 405.87 g/mol

But I'm not sure if there is a whole lot of point, since it's not like anyone's getting pure heroin on the street anyway and even a micron filter wouldn't filter out soluble cuts and would absorb some of the water.

 

[Dobe]

I think it's safe to assume that pure heroin, if available, would not significantly increase the volume. Happy to be proven wrong though...

 

[Dobe]

That would be expected due to additives rather than the heroin itself.

 

[The.Ghost]

Chemistry is not my strongest subject, but I don't think we can assume that all salts have similar properties regarding volume when added to water. Furthermore, volume is not constant, it changes depending on temperature right? So if adding something changes the temperature (or a person is heating their heroin + water) then that would make a difference too right? I'm pretty sure adding sodium chloride to water lowers the temperature?

Not all salts behave the same. Some increase the volume, some decrease it.

From Wikipedia:

The apparent molar volume of a salt is usually less than the molar volume of the solid salt. For instance, solid NaCl has a volume of 27 cm³ per mole, but the apparent molar volume at low concentrations is only 16.6 cc/mole. In fact, some aqueous electrolytes have negative apparent molar volumes: NaOH -6.7, LiOH -6.0, and Na₂CO₃ -6.7 cm³/mole. This means that their solutions in a given amount of water have a smaller volume than the same amount of pure water.

As for temperature change on dissolution, this varies by salt too. Adding ammonium nitrate to water drastically decreases the temperature (this is how instant cold packs work), while solid NaOH will increase the temperature to the point of localized boiling around the hydroxide. NaCl lowers the temperature a bit, with an enthalpy change of solution of +3.87 kJ / mol, or 66.2 J / g (not that much).

Temperature changes obviously affect the properties of a solution. In general, higher temperature = higher volume and higher solubility of solid solutes (dissolved gasses go the other way around). It might be worth mentioning that NaCl's solubility in water is almost independent of temperature. At anything you would call room temperature, it's 36 - 37 g NaCl / 100 mL H₂O.