posted by Sara .
We did a experiment to recognize chemical change and here it is: I'm listing what we did, step by step.
1. Put on your safety goggles. In one row of your spot plate, add five drops of the sodium hydroxide solution to each of four deprssions. Then add two drops of copper(||) nitrate to the first depression, two drops of nickel(||) nitrate to the second depression, two drops of magnesium nitrate to the third, and two drops of iron(|||) nitrate to the fourth. Record your observations. ~ This was the first column we had to do.
2. In a second row, add five drops of the sodium iodide solution to each of three depressions. Then add two drops of lead(||) nitrate to the first depression, two drops of copper(||) nitrate to the second, and two drops of silver nitrate to the third. Record your observations. ~ This was the seond column we had to do.
3. In a third row, add five drops of sodium carbonate to each of three depressions. Then add two drops of calcium nitrate to the first depression, two drops of nickel(||) nitrate to the second depression, and two drops of lead(||) nitrate to the third. Record you observations. ~ This was the third column we did.
For the first column in order if I go, I got the colur blue in the first depression, the colur light blue in the second depression, the colour dark grey in the third depression, and the colur brown in the fourth depression.
The colour blue I got was very light; almost white ~ is there another way to say light, light blue? Also I got precipitate for all of these colours. Is that right? The signs of chemical change for all of these were that new colour arose and precipitate. Bubbles never appeared and neither did heat or light.
For the second column in order if I go, I got the color yellow in the first depression ~ thick at bottom and I got precipitate. For the second depression I got the color brown in the middle which was light brown on the edges. For the third depression I got the colour light yellow in colour; which was almost white.
For the third column in order if I go, I got the color grey-bluish in the first depression which was also precipitate, I got the color light greenish and precipitate for the second depression, and I got the color white; thick at bottom for the third depression.
Now, it says that I have to identify the combinations of chemicals in which chemical changes occured. I don't know what would be a good answer for this question. The chemical changes occured in all of the combinations.
The other question is: What evidence showed that chemical changes had occured?
I wrote that new colur arose and that some combinations also precipitated. Please tell me if anything else was supposed to occur. I kind of had a hard time pouring the solutions; at times I poured too much ~ so I am not sure if I'm right. Your help will be appreciated, thanks:-)
Light blue can also be described as very pale blue, if you want.
Since I wasn't there, I don't know if you got "precipitate for all these colors."
Yes, the color changes and precipitates are indications of chemical changes.
Since chemistry is not my area of expertise, I can't tell you if anything else is "supposed to occur."
I hope this helps.