Chemical Reactions

[kjslugger]

Hi,

I have been trying to write up a new procedure for chemistry lab and need some help. I am looking for some chemical reactions that students can do that show evidence of a color change or a temperature change (hot or cold) or gas evolution or a precipitate that has color (preferably not white). I can not use mercury, lead, chromates. I have mostly nitrates, chlorides and some sulfates to work with.

 

I have already done experiments with Mg and HCl for H2 creation. Copper and Silver Nitrate - too expensive! Calcium chloride and sodium carbonate for precip. Magnesium burning. Copper Carbonate decomposition for CO2.

 

I don't really have any good experiments for colored precipitate formation or temperature change or oxygen gas evolved.

Can anyone suggest ones they have done in high school chemistry? I teach HS chemistry in AZ.

Thanks,

Kjslugger

[Sensei]

I have mostly nitrates, chlorides and some sulfates to work with.

 

If it's not requirement,

how about f.e.

acetic acid + sodium bicarbonate (aka baking soda) -> carbon dioxide (gaseous) + sodium acetate + cold (put electronic thermometer to beaker)

Both can be bought in any supermarket.

 

Later you can get rid of water from sodium acetate,

and show "hot ice".

Edited August 2, 2015 by Sensei

[kjslugger]

Thanks for the suggestion!

If the acetic acid (vinegar) is added slowly enough, not sure you get many bubbles of CO2. They need to do a burning splint test for CO2. How long does it take to remove water from sodium acetate? Class is only 50 min long, but realistically 35-40 min of lab time figuring setup and cleanup.

[Sensei]

Thanks for the suggestion!

If the acetic acid (vinegar) is added slowly enough, not sure you get many bubbles of CO2.

Get beaker 250 mL, add 50-100 mL of 10% vinegar, and add teaspoon of baking soda,

it will be so violent reaction of releasing CO₂, that you will most likely have table dirty..

 

50 mL 10% vinegar can give you nearly 2 Liters of CO₂ gaseous.

Some dissolves in water though, and bubbles will be around entire container.

 

How long does it take to remove water from sodium acetate?

Too many variables. Try it by yourself at home.

That depends on amount of water and power of hot plate, if you want to use it, instead of gas burner, or heating element, or alcohol lamp..

 

Class is only 50 min long, but realistically 35-40 min of lab time figuring setup and cleanup.

Making sodium acetate solid/hot ice is just addition to the main show of this experiment, which is just a few seconds long.

Take electronic thermometer with 0-100 C scale at least.

I have similar model to this -50 +300 C

http://www.aliexpress.com/store/product/Digital-thermometer-Food-thermometer-Air-condtioning-thermometer-Free-shipping-Temperature-range-50-300/912708_699014153.html

and you will show how temperature drops while releasing CO₂.

Edited August 3, 2015 by Sensei

[kjslugger]

Thank you for the info. I know that vinegar and B. Soda is a quick reaction. I have not taken it past that point and removed the water to get sodium acetate. I will have to try it this week before I see students. Thanks for the help!