Quiz: Monday April 25Write the balanced Chemical equation.

1. Copper (II) carbonate, a greenish grey powder, changes to black, and produces a colorless gas, limewater becomes cloudy. The colorless gas also will put out a flame if collected in large enough quantities.

2. Silver colored magnesium ribbon burns in air with a very bright light. The end product is a white chalky solid.

Answers to Quiz: Monday April 25Write the balanced Chemical equation.

1. Copper (II) carbonate, a greenish grey powder, changes to black, and produces a colorless gas, limewater becomes cloudy. The colorless gas also will put out a flame if collected in large enough quantities.

CuCO3 CuO + CO2 5points

2. Silver colored magnesium ribbon burns in air with a very bright light. The end product is a white chalky solid.

2 Mg + O2 2 MgO

Quiz April 26, 2005Write the balanced chemical equation for the following reactions.

1. Ammonium carbonate was heated in a Bunsen burner flame. As the quantity decreased, a bad smell was noted. When tested with cobalt chloride paper, the blue paper turned pink. The gases emitted were also able to put out a lit splint.

2. When the black powder, manganese dioxide, was added to hydrogen peroxide, lots of bubbles formed. The glowing splint, placed above the liquid re-lit, bursting into flames. When the reaction finally ended, the black powder was still there.

3. Why is the fact that the black powder is STILL there important to know when predicting the results of the reaction?

Answers to Quiz April 26, 2005Write the balanced chemical equation for the following reactions.

1. Ammonium carbonate was heated in a Bunsen burner flame. As the quantity decreased, a bad smell was noted. When tested with cobalt chloride paper, the blue paper turned pink. The gases emitted were also able to put out a lit splint.

(NH4)2CO3 2 NH3 + H2O + CO21 1 1 1 1 1 1 1 =8

2. When the black powder, manganese dioxide, was added to hydrogen peroxide, lots of bubbles formed. The glowing splint, placed above the liquid re-lit, bursting into flames. When the reaction finally ended, the black powder was still there.

2 H2O2 2 H2O + O21 1 1 1 1 =5

3. Why is the fact that the black powder is STILL there important to know when predicting the results of the reaction?

That tells us the the black powder was a catalyst – i.e. it doesn’t change in the reaction. It can be left out, or put above the arrow

MnO21 point

Lab 25: 10 points extra credit if turned in COMPLETE

andWell Done

TUESDAY, April 26Lab 25 will be accepted only

until Monday May 2Homework 30 should be complete

Begin Pre-lab for lab 27when you have extra time

I’d like to do that next week

Pre-lab, Lab 25 Part II• Safety cautions:

– hydrogen peroxide is a mild oxidizer, it will burn if it gets into your eyes, or on a cut.

– Ammonium carbonate is also an irritant, make sure the window is open, if you have Asthma, you may go into the hall if the fumes bother you.

– toxic solids can go in the waste-container on the middle lab bench, they NEVER go in the sink.

– Lead is a neurotoxin, avoid exposure and use the smallest possible quantity on the watch-glass.

– FIRST AID for exposure to chemicals – Rinse with lots of water, have your lab partner inform ME immediately, in case further action is required.

• READ EACH STEP CAREFULLY before beginning. Both your safety and your data depend upon this!

• Write observations: Before—During—After for each experiment. Begin at, or after Step 6, We will not do step 9. clean up your lab area. Make sure your name is on a post-it note near your lab station – You get a grade for CLEAN-UP!