Chemistry - December 2007

The total number of bonding electrons in a molecule of formaldehyde (H2CO) is ________.
a. 3
b. 4
c. 6
d. 8
e. 18

2007-12-26 11:45:57 · 2 answers · asked by Anonymous

HNO3

(NH4)2SO4

Br2

CuSO4 5H2O





the numbers are all the little ones, ya know?
if you could tell me how to do them too that'd be GREAT.


:)

2007-12-26 11:43:01 · 4 answers · asked by allyp 2

Which one of the following is most likely to be a covalent compound?
a. KF
b. CaCl2
c. SF4
d. Al2O3
e. CaSO4

2007-12-26 11:39:51 · 2 answers · asked by svince1884 1

Which one of the following is most likely to be an ionic compound?
a. KF
b. CCl4
c. CS2
d. CO2
e. ICl

2007-12-26 11:39:08 · 4 answers · asked by svince1884 1

Specifically does such a mix have enough glycol in it to offset the expansion of the water or does it need to be stronger? Blockages from frozen fluids are not a concern, expansion is though.

2007-12-26 11:33:01 · 2 answers · asked by John H 1

Help! My teacher has never taught my class how to solve problems similar to this. Instead he gave a summative lab with very similar questions as the one show above. And sadly our textbooks do not explain how to solve such a problem very well. Texas high school textbooks suck!

I have tried everything. I have added the g/mol & amu's. I have even solved for the percentage that each element occupies in the problem---as so far I have been unsuccessful. Can someone please tell me how to solve this problem?

Here's the question:

1)How many Cl- ions are present in 2.00 mol of KCl?

[A] 12.04 * 10^23
[B] 6.02 * 10^24
[C] 2.00
[D] 0.5

A link or diagram would be very appreciated.

2007-12-26 11:23:06 · 1 answers · asked by Anonymous

Cu(OH)2 (s) + 2HNO3 (aq) ---> Cu(NO3)2 (aq) + 2H20 (l)
Fe2O3 (s) + 3CO (g) ---> 2 Fe (s) + 3CO2 (g)
Sr(NO3)2 (aq) + H2SO4 (aq) ----> SrSO4 (s) + 2HNO3(aq)
4Zn(s) + 10H+ (aq) + 2NO3- (aq) ---> 4Zn 2+(aq) + N2O (g) + 5H20 (l)

they can be precipitation or acid base reactions too

2007-12-26 10:50:32 · 2 answers · asked by Anonymous

I'm not so much interested in straight answers as much as I'm interested in the work that's involved in figuring out these problems. D: I need to know how to get from one point to another on problems like these if I have a hope of passing the test.

1. In the reaction shown below 4.0 mol of NO is reacted with 4.0 mol of O2

2NO + O2 ---> 2NO2

a. Which is the excess reactant, and which is the limiting reactant?
b. What is the theoretical yield, in units of mol, of NO2?

2. In the reaction shown below 64g CaC2 is reacted with 64g H2O.

CaC2(s) + 2H2O(l) ---> C2H2(g) + Ca(OH)2(s)

a. Which is the excess reactant, and which is the limiting reactant?
b. What is the theoretical yield of C2H2?
c. What is the theoretical yield of Ca(OH)2?

3. In the reaction shown below, 28g of nitrogen are reacted with 28g of hydrogen.

N2(g) + 3H2(g) ---> 2NH3(g)

a. Which is the excess reactant, and which is the limiting reactant?
b. What is the theoretical yield of ammonia?
c. How many grams of the excess reactant remain?

2007-12-26 10:25:09 · 2 answers · asked by Anonymous

need real answers please help

2007-12-26 09:50:28 · 7 answers · asked by sophie 1

can it melt roots in a sewer line? (clean out provides the venting outside).

2007-12-26 09:45:38 · 2 answers · asked by MrZ 6

Okay, how do you make one state of matter another? Basically.

What would I do to Ice to make it a liquid?
What would I do to Ice to make it a gas?

What would I do to water to make it a solid?
What would I do to water to make it a gas?

What would I do to mist to make it water?
What would I do to mist to make it ice?

Just wondering, thank you! =D

2007-12-26 09:04:20 · 7 answers · asked by Richard S 2

How would you go about writing a balanced equation describing the reaction of sodium metal with water to produce hydrogen gas and sodium hydroxide?

-__-
Me + Chemistry = Stress
Also, if anyone is up to it:

Manganese metal can be prepared by the thermite process:
4Al(s) + 3MnO2(s) ---> 3Mn(l) + 2Al2O3(s)

Molar masses being:
4Al(s) = 26.98
3MnO2(s) = 86.94
3Mn(l) = 54.94
2Al2O3(s) = 101.96

a) If you start with 8 moles of Al, how many moles of Mn can be produced? (All other reactants are in excess.)
b)What mass of Al2O3 can be made from 200 g MnO2 and excess Al?

Any help is much appreciated.

2007-12-26 08:42:53 · 9 answers · asked by Anonymous

2007-12-26 06:18:10 · 4 answers · asked by Anonymous

1.From sucrose
2.from starch

2007-12-26 05:55:13 · 3 answers · asked by Angel_24 1

2007-12-26 05:22:49 · 7 answers · asked by Anonymous

2007-12-26 05:08:35 · 7 answers · asked by Anonymous

for project titration

2007-12-26 04:46:20 · 1 answers · asked by dk 1

2007-12-26 03:57:40 · 3 answers · asked by Anonymous

2007-12-26 03:54:11 · 2 answers · asked by SureymaK 1

I know that in the equation, there are a couple pf n's...
The equation is P=(nRT/v-nb)-(n^2-a/V^2)

I know that the first n, the one from nRT is equal to the number of moles, but what about the other n's o.0 what do they equal....

Thank you in advance

2007-12-26 03:50:58 · 3 answers · asked by The Book Smart Game Freak 3

2007-12-26 03:48:03 · 1 answers · asked by teresa l 1

2007-12-25 19:52:48 · 2 answers · asked by kristine lovele n 1

Ammonium hydrogen sulfide is a crystalline solid that decomposes as follows:
NH4HS (s) --> NH3 (g) + H2S (g)

Some solid NH4HS is placed in an evacuated vessel at 25 degrees C. After equilibrium is attained, the total pressure insde the vessel is found to be 0.659 atmosphere. Some solid NH4HS remains in the vessel at equilibrium. For this decomposition, write the expression for Kp and calculate its numerical value at 25 degrees C.

2007-12-25 16:28:28 · 4 answers · asked by Alyssy 2

1. Some rocket engines use a mixture of hydrazine, N2 H4, and hydrogen peroxide, H2 O2, as the propellant. The reaction is given by the following equation.

N2H4 (l) + 2H202 (l) ---> N2 (g) + 4H2O (g)

Side question: Why does the need of (l) liquid or (g) or aq(which is aqueous, dissolving in water) need to be specified. I've been doing problems with these signs since I started balancing redox reactions several chapters in general chemistry.. it hasn't seemed to affect the final answer.

a. Which is the limiting reactant in this reaction when 0.750 mol N2H4 is mixed with 0.500 mol H2O2?

b. How much of the excess reactant, in moles, remains unchanged?

c. How much of each product, in moles, is formed/

My work:
a. answer: 0.750 mol N2H4 produces 3 mol H20 ( I just looked at the ratios of H20 produced from each amount. )

b. I don't know how to find that. (????)

c. I put 0.25 mol N2, and 1 mol H20 (from plug, but I don't see why you can't plug in 0.75 mol N2H4 to find this answer)

2007-12-25 15:48:12 · 6 answers · asked by Anonymous

i have bone structure, but does anybody knows how to get more???

2007-12-25 14:44:35 · 1 answers · asked by mkl 1

For example, Neutralization reactions like these below (but that DO NOT have CO2 as an end product, but rather some other harmless gas):

HC2H3O2 + NaHCO3 ===> NaC2H3O2 + H2CO3 H2CO3 ===> H2O + CO2

MgCO3(s) + 2 HCl(aq) -----> MgCl2(aq) + H2O(l) + CO2(g)

2007-12-25 14:38:36 · 2 answers · asked by Anonymous

Find the particular solution of DE, θ dπ/dθ = 2π, π=9 when θ = -½

2007-12-25 14:20:08 · 2 answers · asked by JESS 1

i already have SF6. i need three more. also, are octahedrals polar or not?

2007-12-25 14:06:36 · 3 answers · asked by xx528 1

2007-12-25 12:49:55 · 4 answers · asked by Zyxel 3

Explain in terms of particle arrangement.

2007-12-25 12:19:59 · 7 answers · asked by wuw7676 1