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Author Topic: Chemistry reactivity lab help?  (Read 334 times)
CharroTh_P
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« on: May 10, 2011, 03:50:01 PM »

In my lab, there're 10 different chemical that I pair them up and mixed them together.
For each reaction I have to write down the evidence of reaction, balanced equation and litmus test
I need help with writing balanced equation including the states of all the products.... and I'm not sure if the evidence of reaction and litmus test are right. Please help me !
Note: for the aqueous in this lab I added small amount of chemicals in water, and in reactions I added 5 drops of each solutions in the test tube of other solutions
For litmus test, I placed the red and blue litmus paper on top of the test tube (the instructions said so) and I'm not sure if that's right because most of the papers didn't turn to any color

Here are the results I got:
1.)NH4Cl (aq) + NaOHno evidence of reaction   litmus paper didn’t change

2.)BaCl2 (aq) + Na2CO3no evidence of reaction (I think this one is wrong, is it suppose to have white precipitate??)Litmus paper didn’t change

3.)CuSO4 (aq) + NH3 (l)white precipitate solids form   blue paper tinted red

4.)NiCl2 (aq) + Na3PO4 (aq)white precipitate solids form  litmus paper didn’t change

5.)Na2CO3 (aq) + HCl (l)strong smelllitmus paper didn’t change

6.)HCl (l) + Mg (s) ** for this one I put 2cm of thin Mg metal in HCl solution
Mg dissolves in HCL, smell, and bubbles Blue paper tined red

7.)NaOH (l) + HCl (l) temperature increased for 1C (really little change) litmus paper didn’t change

8.)Mg (s) + fire(using propane gas and aiming for blue color of fire)  Mg burned and produces white bright light left with white ashes (I’m pretty sure this one is right)

Please help me to do this lab correctly, I think it's okay of the evidence of reaction is not right but I really need help with balancing equations and litmus test
Thanks! Smiley
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Umar
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« Reply #1 on: May 10, 2011, 04:12:01 PM »

1. on warming the mixture, NH3 gas evolves and turns red litmus to blue. NaOH + NH4Cl = NH3 + NaCl + H2O.
2. Yes it would give white ppt soluble in acid with evolution of CO2 gas that turn lime water milky.
3. NO. the wouldn't be ppt. rather soluble complex of [Cu(NH3)4]SO4 which has more deep blue colour than CuSO4.
4. 3NiCl2 + 2Na3PO4 = Ni3(PO4)2 + 6NaCl. Compounds of Ni are coloured because Ni is transition metal. You might have missed the colour.
5. You are wrong. This reaction will produce CO2 gas that turns lime water milky and it does not have odour.
6. This reaction would produce H2 gas that has a pop sound when a burning splint is brought near the evolving gas. 2HCl + Mg = MgCl2 + H2. MgCl2 is a neutral salt couldn't have changed the colour of litmus paper.
7. Correct.  This is neutralizationoreactionon between a strong acid and a strong base producing neutral salt solution.
8.CORRECT>
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