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How do you separate two powders that are mixed together? ex. baking soda and calcium carbonate

ashleybrown5 wrote:How do you separate two powders that are mixed together? ex. baking soda and calcium carbonate

A good explanation for this is in the wiki. Generally, I just look for distinguishable properties from multiple powders.

I have a question pertaining to the analysis "questions" that are generally asked at the end. Is it necessary to write in full sentences, or can a list be presented? Most test have an open ended question and a bunch of lines underneath (like nationals). Could someone please let me know if a list could be used (mainly at higher level competitions) ? I am aware that this could vary between supervisors, but I would like to know the general consensus.

Thanks!

Several years ago I bought a polymer / fiber kit for crimebusters that was really good. I can't seem to remember or find where I bought it from. Does anyone have a good site for getting fibers and plastics for crimebusters?

My team has had trouble identifying the difference between water and hydrogen peroxide since they are both odorless and have the same pH. We have tried shaking them and looking for bubbles, but both liquids bubble for us. Are there other methods we could try to effectively identify the difference between these liquids?

knowthewrightstuff wrote:My team has had trouble identifying the difference between water and hydrogen peroxide since they are both odorless and have the same pH. We have tried shaking them and looking for bubbles, but both liquids bubble for us. Are there other methods we could try to effectively identify the difference between these liquids?

You probs have some old, old peroxide. Spontaneous decomposition

shrewdPanther46 wrote:

knowthewrightstuff wrote:My team has had trouble identifying the difference between water and hydrogen peroxide since they are both odorless and have the same pH. We have tried shaking them and looking for bubbles, but both liquids bubble for us. Are there other methods we could try to effectively identify the difference between these liquids?

You probs have some old, old peroxide. Spontaneous decomposition

Thanks for the advice. We did notice that our bottle was expired last year so we bought a new bottle, but we still had the same problem. Do you just use a plastic test tube to shake it in?

We have glass, but its more or less the same.

knowthewrightstuff wrote:My team has had trouble identifying the difference between water and hydrogen peroxide since they are both odorless and have the same pH. We have tried shaking them and looking for bubbles, but both liquids bubble for us. Are there other methods we could try to effectively identify the difference between these liquids?

One way to tell them apart is to put some iodine in it. If it fizzes, it's hydrogen peroxide. If not, water.

SOCoach wrote:Several years ago I bought a polymer / fiber kit for crimebusters that was really good. I can't seem to remember or find where I bought it from. Does anyone have a good site for getting fibers and plastics for crimebusters?

The Society of Plastics Engineers sells a pretty comprehensive kit called Hands-On Plastics that has most everything except PMMA. A cheap way to get fibers is to go to the local craft/fabric store and see if they'll let you have 1-inch samples of fabrics for free or for really cheap.

Tailsfan101 wrote:

knowthewrightstuff wrote:My team has had trouble identifying the difference between water and hydrogen peroxide since they are both odorless and have the same pH. We have tried shaking them and looking for bubbles, but both liquids bubble for us. Are there other methods we could try to effectively identify the difference between these liquids?

One way to tell them apart is to put some iodine in it. If it fizzes, it's hydrogen peroxide. If not, water.

I'm not sure how you got that to happen bc if you try to write a balanced equation for it, you won't get a product that will be in gaseous form.

pikachu4919 wrote:

Tailsfan101 wrote:

knowthewrightstuff wrote:My team has had trouble identifying the difference between water and hydrogen peroxide since they are both odorless and have the same pH. We have tried shaking them and looking for bubbles, but both liquids bubble for us. Are there other methods we could try to effectively identify the difference between these liquids?

One way to tell them apart is to put some iodine in it. If it fizzes, it's hydrogen peroxide. If not, water.

I'm not sure how you got that to happen bc if you try to write a balanced equation for it, you won't get a product that will be in gaseous form.

I found something on the H2O2/KI reaction here.