Help with a chemistry lab (What was left after evaporation)

[loopydo]

Hello,

This is the first time I have posted to these forums. It looks like an organized community, so I thought I might ask a question about something I cannot figure out. We did a lab in my chemistry class a few days ago, and it was about physical and chemical changes of matter.

I am trying to figure out what was left in a dish after we evaporated some chemicals.

The process to get to this point was:

1. We placed 3mL of HCl and a piece of foil into a test tube, and then quickly put our thumb over the opening to contain the pressure and speed up the process. After our thumbs could not hold the pressure, we quickly took our thumbs off and held a flaming wooden stick over the test tube, which created a pop.

2. After the reaction was over, we poured the contents into an evaporating dish, and added 3mL of water to the evaporation dish.

3. We then slowly heated the evaporating dish. After it was completely evaporated my partner and I gathered these observations:

It turned yellow.

Became solid with clumps of the "yellow pollen" like objects.

My question is what do you think was left in the evaporating dish? What kind of powder was it?

 

The second question starts with the leftovers from the evaporation dish.

1. We added 10mL of water to the evaporated substance.

2. We transferred it to a clean test tube.

3. We added 4-5 drops of ammonia to the test tube.

Our observations were:

Top of substance looked "icy"

The ammonia could be seen spreading downwards.

Tilted test tube, and it seemed to retain it's solid shape.

My question is what do you think was the new substance that was produced after ammonia was added at the end?

[Psycho]

Hello,

This is the first time I have posted to these forums. It looks like an organized community, so I thought I might ask a question about something I cannot figure out. We did a lab in my chemistry class a few days ago, and it was about physical and chemical changes of matter.

I am trying to figure out what was left in a dish after we evaporated some chemicals.

The process to get to this point was:

1. We placed 3mL of HCl and a piece of foil into a test tube, and then quickly put our thumb over the opening to contain the pressure and speed up the process. After our thumbs could not hold the pressure, we quickly took our thumbs off and held a flaming wooden stick over the test tube, which created a pop.

2. After the reaction was over, we poured the contents into an evaporating dish, and added 3mL of water to the evaporation dish.

3. We then slowly heated the evaporating dish. After it was completely evaporated my partner and I gathered these observations:

It turned yellow.

Became solid with clumps of the "yellow pollen" like objects.

My question is what do you think was left in the evaporating dish? What kind of powder was it?

 

Well to start with you have to ask yourself a few questions, the first would be what did you originally start with, you have HCl, but what was the foil made from?

 

The second question you have to ask is what are you getting rid of when you use the flame to make a pop, as that obviously can't be part of the end product but must have been in the original reactants.

 

Then when you have an idea of what it might be look the chemical up on google to see what it looks like, if it is a yellow powder you have the right one.

The second question starts with the leftovers from the evaporation dish.

1. We added 10mL of water to the evaporated substance.

2. We transferred it to a clean test tube.

3. We added 4-5 drops of ammonia to the test tube.

Our observations were:

Top of substance looked "icy"

The ammonia could be seen spreading downwards.

Tilted test tube, and it seemed to retain it's solid shape.

My question is what do you think was the new substance that was produced after ammonia was added at the end?

Well you will have to work out the original product first, but then you have to work out what is being added to it, what is the chemical formula of ammonia.

 

Then you have to work out what is being substituted for what and then what physical properties that has, so in this case whether it is white crystals.