Chemistry - September 2007

What is the source of colors in exploding fireworks and during the burning of artificial logs?

2007-09-25 16:24:20 · 7 answers · asked by Anonymous

Assume that you start with 4 mole of magnesium metal, determine:

1.The number of grams of MgO(s) that would be produced in the following reaction (enter your answer with 4 significant figures):


Mg(s) + 1/2 O2(g) -----> MgO(s)


cont....


2.The number of grams of Mg3N2(s) that would be produced in the following reaction (enter your answer with 4 significant figures):


Mg(s) + 1/3 N2(g) -----> 1/3 Mg3N2(s)

2007-09-25 16:19:09 · 1 answers · asked by Anonymous

2007-09-25 16:08:14 · 7 answers · asked by LumpiaEATER ! 2

Assume that you start with 4 mole of magnesium metal, determine:

1. The number of grams of MgO(s) that would be produced in the following reaction (enter your answer with 4 significant figures):


Mg(s) + 1/2 O2(g) -----> MgO(s)

2007-09-25 16:00:24 · 2 answers · asked by Anonymous

How would you explain this and how does it work?

size depends on the priciple quantum number, n .

but when I do the electron configurations, I get different letters and numbers

like Cr: 4s^13d^10

2007-09-25 15:52:48 · 2 answers · asked by Anonymous

3Cu(s) + 8HNO3(aq) ——> 3Cu(NO3)2(aq) + 2NO(g) + 4H2O(l)

What happens in the above reaction? Why?

(a) Redox (State what is being oxidized and what is being reducted)

(b) Acid-Base

(c) Precipitattion Reaction

2007-09-25 15:42:43 · 3 answers · asked by Anonymous

1) How many grams of Na2Cr2O7 should be added to a 100.0-mL volumetric flask to prepare 0.025 M Na2Cr2O7 when the flask is filled w/ water?

2) You wish to prepare 0.12 M HNO3 from a stock solution of nitric acid that is 15.8 M. How many mL of the stock solution do you require to make up 1.00 L of 0.12 M HNO3?

3) A chemist added an excess of sodium sulfate to a solution of soluble barium compound to precipitate all of the barium ion as barium sulfate, BaSO4. How many grams of barium ion are in a 458-mg sample of the barium compound if a solution of the sample gave 513 mg BaSO4 precipitate? What is the mass % of barium in the compound?

I attempted these questions and my answer was way off from the right ones and I followed an example.

2007-09-25 15:15:24 · 1 answers · asked by keya_na 2

2007-09-25 14:16:57 · 12 answers · asked by Tania T 1

I have a mixture of dry sand and sugar, I have to separate the mixes in under 10 minutes..... i'm stumped! I don't know what technique to use.

Please help me!

2007-09-25 14:12:12 · 6 answers · asked by iyikka14 3

When K3PO4 is dissolved in water, why does the solution turn basic?

KOH is strong and H3po4 is weak

If K is the salt of KOH, then K would make KOH with water which would form H+ ions and turn the solution acidic?

I know its wrong, I just dont know why..

If someone could help.. thanks..

2007-09-25 14:01:41 · 3 answers · asked by Dhruv 1

2007-09-25 14:00:18 · 5 answers · asked by skittles 1

2007-09-25 13:49:33 · 5 answers · asked by anonymous 3

2007-09-25 13:46:19 · 1 answers · asked by hummy 1

2007-09-25 13:37:06 · 3 answers · asked by Anonymous

2007-09-25 13:35:26 · 4 answers · asked by Ancientday 1

is which of the following:

A)Monomers serve as building blocks for polymers
B)Monomers are joined together by he process of hydrolysis
C)Cells typically make all their macromolecules from a set of 40-50 common monomers and a few other ingredients that are rare.
D)DNA is built from just four kinds of monomers
E)The monomers used to make polymers are essentially universal.

2007-09-25 13:31:53 · 2 answers · asked by Travelingstar 1

Describe some clues you might observe during the following events that could support the conclusion that a chemical change is occuring:
a. An antacid tablet is dropped into water
b. A ring of scum forms around a bathtub
c. Iron rusts
d. a firecracker explodes

I am stuck on this question on my homework and would appreciate if someone helps me. Thanks!!!

2007-09-25 13:28:07 · 2 answers · asked by Living la vida loca!!! 2

Are food colourings safe?

2007-09-25 13:25:48 · 7 answers · asked by Anonymous

A)Floating ice on a pond insulates the liquid water below, slowing its rate of freezing.
B)If ice sank,the oceans would eventually freeze solid
C)The hydrogen bonds in ice are less stable than the hydrogen bonds in liquid water
D)Ice is less dense than liquid water
E)Water naturally exist in all three physical states on Earth.

2007-09-25 13:17:06 · 10 answers · asked by Travelingstar 1

Is an orbital completely filled before electrons fill the next outer orbital? I was told by another teacher that there were two electrons in the first orbital and then 8 in every other one, is this true?

I need this simple because I will be teaching it to 8th graders. I don't know how to explain electron config. simply and without formulas!

2007-09-25 13:16:41 · 2 answers · asked by sarah13star 2

2007-09-25 13:14:08 · 0 answers · asked by brunette.girly 1

2007-09-25 13:11:10 · 1 answers · asked by Anonymous

is which of the following:

A. Is more electronegative than hydrogen atoms
B. Is attracted to the negatively charged atoms of other molecules.
C.Attracts electrons less strongly than the hydrogen atoms
D Is Electrically neutral
E. Is more positively charged than the hydrogen atoms

2007-09-25 13:10:38 · 3 answers · asked by Travelingstar 1

carbon nitrogen and hydrogen

2007-09-25 11:05:06 · 4 answers · asked by Anonymous

A carbon atom forms four bonds to the unspecified number of other atoms. To form these
bonds, the carbon atom uses a combination of hybrid and/or atomic orbitals. Which of the following
combinations of orbitals is not possible?


a) sp2, sp2, sp2, sp5
b) sp2, sp2, sp5, sp5
c) sp3, sp3, sp, p
d) sp3, sp3, sp2, sp5
e) sp2, sp2, sp2, p


I really need an explanation as well.

2007-09-25 10:58:52 · 1 answers · asked by Anonymous

If it is not bubbling, it does not. So what about the bubbling makes this happen?

2007-09-25 10:53:44 · 3 answers · asked by Okay.... 3

How many square kilometers of ocean will be covered by the slick formed when two barrels of oil are spilled? (1 barrel= 31.5 gallons) (1 liter= 1 decimeter^3) (1 liter or 1 decimeter^3= 1.057 quarts)...... SHOW ALL WORK AND STEPS NOT JUST AN ANSWER.

2007-09-25 10:52:41 · 1 answers · asked by hiyas123 3

How do the test on known solutions containing cations and anions make it possible to identify the cations or anions in an unknown substance?

2007-09-25 10:44:05 · 2 answers · asked by RogerDodger 1

2007-09-25 10:39:53 · 4 answers · asked by sammyrulesforever 1

cOMPARE ALLOTROPES AND ISOTOPES OF CARBON?

aND PLS NAME AND DESCRIBE BRIFLY SOME ISOTOPES USED IN THE FIELD OF MEDICINE...






PLEASE!!! IM A NURSE AND IVE GOT A TEST TOMORROW. THIS TOPIC IS THE ONE I DONT UNDERSTAND. OKI?

2007-09-25 10:34:49 · 1 answers · asked by Anonymous