Crime Busters B

[NewSciolyer]

I feel like there seems to be a wide range of pH for some powders. I can't remember on the top of my head, but I think there was one powder where a few sources said the pH was 6, and but some other sources say that it was upwards of 9. What do you guys think of this?

[Locoholic]

I feel like there seems to be a wide range of pH for some powders. I can't remember on the top of my head, but I think there was one powder where a few sources said the pH was 6, and but some other sources say that it was upwards of 9. What do you guys think of this?

I’d say pH is actually pretty reliable. Go with what is said on the SciOly wiki, because that’s what I did and I haven’t had any problems with testing (pH-wise). Also make sure you have good pH paper. If it’s greenish, I kinda just assume it’s basic (pH 8), and if it isn’t greenish, then I just assume the pH is just 6 or 7. Unless it turns orange and it’s vitamin c.

[CPScienceDude]

I feel like there seems to be a wide range of pH for some powders. I can't remember on the top of my head, but I think there was one powder where a few sources said the pH was 6, and but some other sources say that it was upwards of 9. What do you guys think of this?

I’d say pH is actually pretty reliable. Go with what is said on the SciOly wiki, because that’s what I did and I haven’t had any problems with testing (pH-wise). Also make sure you have good pH paper. If it’s greenish, I kinda just assume it’s basic (pH 8), and if it isn’t greenish, then I just assume the pH is just 6 or 7. Unless it turns orange and it’s vitamin c.

Use This. It was made by the forensics national event supervisor.

[jllooi01]

I went to an invitational, and I'm pretty sure one of the powders they gave was not on the list of powders they can give. It was insoluble in water, had no reaction to HCl or iodine, and I tested the pH, it showed up as a pH of 10 ish. Anyone have any idea?

[Locoholic]

I went to an invitational, and I'm pretty sure one of the powders they gave was not on the list of powders they can give. It was insoluble in water, had no reaction to HCl or iodine, and I tested the pH, it showed up as a pH of 10 ish. Anyone have any idea?

Maybe sodium acetate?

[SilverBreeze]

I went to an invitational, and I'm pretty sure one of the powders they gave was not on the list of powders they can give. It was insoluble in water, had no reaction to HCl or iodine, and I tested the pH, it showed up as a pH of 10 ish. Anyone have any idea?

Could it be sand(if pH were messed up) or chalk? Without a description of the powder, it's hard to say. Check your pH paper?

I went to an invitational, and I'm pretty sure one of the powders they gave was not on the list of powders they can give. It was insoluble in water, had no reaction to HCl or iodine, and I tested the pH, it showed up as a pH of 10 ish. Anyone have any idea?

Maybe sodium acetate?

Sodium acetate is very soluble, so doesn't seem like the first choice, and pH is usually closer to 8.

EDIT: Also remember to wait before deciding a powder is insoluble, as it can take time.

[pecanchu3246]

What is the best to study for crime busters because I got this event and I have no idea what I am doing and how to study.

It really helps to have all of the materials (powders, metals, hcl, iodine, liquids, plastics, fibers, testing kits/supplies, etc) so you can practice frequently. The scioly wiki is really good for crime busters. I don't find the stuff on soinc that useful, but you can take a look.

thanks for the help I appreciate it.

[jllooi01]

I went to an invitational, and I'm pretty sure one of the powders they gave was not on the list of powders they can give. It was insoluble in water, had no reaction to HCl or iodine, and I tested the pH, it showed up as a pH of 10 ish. Anyone have any idea?

Could it be sand(if pH were messed up) or chalk? Without a description of the powder, it's hard to say. Check your pH paper?

I went to an invitational, and I'm pretty sure one of the powders they gave was not on the list of powders they can give. It was insoluble in water, had no reaction to HCl or iodine, and I tested the pH, it showed up as a pH of 10 ish. Anyone have any idea?

Maybe sodium acetate?

Sodium acetate is very soluble, so doesn't seem like the first choice, and pH is usually closer to 8.

EDIT: Also remember to wait before deciding a powder is insoluble, as it can take time.

I don't think it was sand, it was white with fairly consistent particles. Also, it was the first powder I tested, and I let it sit the entire time. It did not dissolve.

[Locoholic]

I don't think it was sand, it was white with fairly consistent particles. Also, it was the first powder I tested, and I let it sit the entire time. It did not dissolve.

Well, sand can be a major outlier when it comes to properties, so I wouldn't rule it out. Once, I had a consistent white powder at a competition with no black specks or anything, and it turned out to be sand. Also, it could be cornstarch because that has a pH of 8 (closer to 10 than most powders), it's consistent and white, and it doesn't fizz in HCl. It should turn iodine black, which I know was not what your test showed but it sometimes turns black-ish and not totally black (for me at least). The only other problem is that it sorta solidifies with water, and I don't think that matched what you tested.

Honestly I wouldn't bother with that powder because it's probably either an error in testing or a powder not allowed in Crime Busters, and in both cases there's nothing you can really do about it.

[dholdgreve]

I went to an invitational, and I'm pretty sure one of the powders they gave was not on the list of powders they can give. It was insoluble in water, had no reaction to HCl or iodine, and I tested the pH, it showed up as a pH of 10 ish. Anyone have any idea?

Could it be sand(if pH were messed up) or chalk? Without a description of the powder, it's hard to say. Check your pH paper?

Maybe sodium acetate?

Sodium acetate is very soluble, so doesn't seem like the first choice, and pH is usually closer to 8.

EDIT: Also remember to wait before deciding a powder is insoluble, as it can take time.

I don't think it was sand, it was white with fairly consistent particles. Also, it was the first powder I tested, and I let it sit the entire time. It did not dissolve.

So... Just curious... If it wasn't soluble, how did the pH go from neutral to that alkaline? Something is amiss I think!