Chemistry - April 2007

2007-04-09 04:10:32 · 4 answers · asked by MSK88 1

The pH will..?

2007-04-09 03:33:17 · 3 answers · asked by sdelesio319 1

C6H8O6, Ka= 8.0x10^-5

2007-04-09 03:28:08 · 2 answers · asked by sdelesio319 1

Lead(II) fluoride(PbF2), lead(II) chloride(PbCl2), lead(II) bromide(PbBr2), or lead(II) iodide(PbI2).

*All of which are slightly soluble in water.

2007-04-09 02:46:47 · 1 answers · asked by kpease214 1

.....for silver chloride?

2007-04-09 01:55:23 · 3 answers · asked by Anonymous

I'm learning about chemical bonding for an A level in biology - as I'm doing this distance I'm finding it difficult to know who to ask.
The question was to draw how Calcium connects to water...
So I did Oxygen in the centre connected with 4 Hydrogen connected round the outside (the other 2 oxygen in the inner ring). I could have this all completely wrong but if anyone can explain and easy way I can work out how they would be connected I would really appreciate it! :-) I then need to add calcium in there somewhere???

2007-04-09 01:52:20 · 3 answers · asked by bimbleberry3 1

Equation:

2SO2(g) + O2(g) yields 2SO3(g) change in H degrees is less than 0.

1. Increasing the pressure
2. Increasing the temperature
3. adding a catalyst

2007-04-09 01:48:20 · 2 answers · asked by Anonymous

I have 3 questions,

1. Which one of the following equilibrium mixture will not be affected by a change in pressure?

a. CH3CH2CH2OH(g) CH3CH=CH2(g) + H2O(g)
b. BaCO3(s) BaO(s) + CO2(g)
c. H2(g) + Cl2(g) 2HCl(g)
d. O2(g) + 2Hg(l) 2HgO(s)

------- is the answer b?

2. Iron has a atomic number of 26. What is the electron configuration of the iron in FeCl3?

a. 1s22s22p63s23p63d34s2
b. 1s22s22p63s23p63d6
c. 1s22s22p63s23p63d5
d. 1s22s22p63s23p63d64s2

-------Is the answer a?

3. The hybridization of the nitrogen atom in the molecule NF3 is

a. sp2
b. spd
c. sp3
d. sp3d

------ How do you do this?

2007-04-09 01:43:24 · 2 answers · asked by superman 1

I know that the thermal stability of the S-block carbonates increases down each group. Down group 2, cation size increases, while the charge on each ion stays the same. Charge density therefore decreases and the cation is less able to polarise the anion...the degree of covalency therefore decreases down the group.. and thermal stability increases.

Does this imply that covalent bonds are weaker than ionic bonds?

Also, the group 2 chloride experimental lattice enthalpies are higher than the predicted values. The difference between the two decreases as you go down the group (i.e. as covalency decreases)....bond polarisation increases...more energy is needed to break the bonds in the lattice than predicted......doesn't this suggest that covalent bonds are stronger than ionic bonds??

In short,
If anyone can explain why the thermal stability of S-block carbonates increases down groups 1 and 2, I would be very grateful.

2007-04-09 01:26:32 · 2 answers · asked by Deezee 1

Is this reaction a redox reaction? Is there any change in oxidation numbers?

Aluminium nitrate + concentrated sulfuric acid

I heard that concentrated sulfuric acid acts differently from the dilute acid. What are the properties of the concentrated acid?

2007-04-09 00:33:46 · 3 answers · asked by Anonymous

2007-04-09 00:21:20 · 7 answers · asked by Andre B 1

i know that an anode is a positively charged electrode, but can "anodes" also mean the positively chargeds ions between the electrodes? im asked to draw an electric field with anodes?

2007-04-08 23:55:15 · 5 answers · asked by Anonymous

Can someone explain to me the dative covalent bond in detail. or you can give any useful websites if you want

2007-04-08 22:50:45 · 2 answers · asked by Anonymous

By adding some aqueous chlorine to some aqueous bromide ions, chloride ions are formed with bromine solution.

If i then add a solution of hexane to the bromine product what is the colour change for hexane and what does the test show?

Thx

2007-04-08 22:11:21 · 8 answers · asked by Anonymous

2007-04-08 22:05:31 · 1 answers · asked by kinana m 1

2007-04-08 21:58:17 · 2 answers · asked by kinana m 1

The possible combinations of the various isotopes of hydrogen and oxygen result in the existence of _________ types of water molecules.

Fill in the blanks.
I think this relates to "heavy water"

2007-04-08 21:53:36 · 3 answers · asked by Anonymous

i was doing my homework and im totally lost...can anyone out there help me out here??

question 1-4refer to the following aqueous solutions.all concentrations are 1M
A. H2C204(oxalic acid) and KHC2O4(potassium hydrogen oxalate)
B.KNO3 AND HNO3
C. NH3 AND NH4NO3
D. C2H5NH2 AND KOH
E. CH3NH2 AND HC2H3O2

1.The most acidic solution:..i thinks its a...but im not sure
2.the solution with the pH nearst7
3 a buffer with a pH>7? I THINK ITS C
4 a buffer with a pH<7?

THANK YOU

2007-04-08 21:51:00 · 3 answers · asked by Charles W 1

3.5 kJ of heat are added to a 28.2 g sample of iron at 20 C(degree celcius). What is the final temperature of the iron in kelvins?

When my teacher converted 3.5kJ to J, he got 3500J. I thought kilo was bigger??? Shouldn't it be .0035J?

2007-04-08 20:11:49 · 4 answers · asked by Philip C 1

Suppose you have to burn a piece of charcoal.
During combustion of the charcoal heat energy is released, so it is exothermic reaction, but heat is required to start the whole burning process! When we ignite the fuel we need to light a march first, which first gives some heat energy to the charcoal before the charcoal starts reacting with oxygen in the air. But on thw whole, the heat energy released during burning is much more than that required to start the reaction, so it is exothermic?

So at the beginning the burning of charcoal is an endothermic reaction, and after that it becomes exothermic? Can we separate combustion into 2 stages? Thanks!

2007-04-08 18:23:42 · 6 answers · asked by Anonymous

2007-04-08 17:32:36 · 4 answers · asked by rich4lor 1

Calcium hydride, CaH2, reacts with water to form hydrogen gas.
CaH2(s) + 2 H2O(l) Ca(OH)2(aq) + 2 H2(g)

This reaction is sometimes used to inflate life rafts, weather balloons, and the like, where a simple, compact means of generating H2 is desired. How many grams of CaH2 are needed to generate 17.0 L of H2 gas if the pressure of H2 is 760. torr at 28°C?
______ g

2007-04-08 17:17:16 · 2 answers · asked by lola_boo 1

I really need it for a lab report I am doing.

2007-04-08 16:16:11 · 1 answers · asked by shiftcomma3 2

2007-04-08 16:04:37 · 2 answers · asked by luke c 1

Why does the amount of surface area of a reactant only affect heterogeneous reactions and NOT homogeneous reactions?

2007-04-08 15:06:08 · 2 answers · asked by Anonymous

C6H5COOK(aq) yields H+(aq) + C6H5COO-(aq)

If a .045M solution of benzoic acid has an (H+)=1.7x10^-3, what is the Ka of the benzoic acid?

2007-04-08 14:59:43 · 2 answers · asked by Anonymous

solubility of Cu(OH)2 is 1.72e-6 gram per 100 mililiters of solution at 25 C

2007-04-08 14:44:59 · 1 answers · asked by Katrin 1

(Sorry for reposting but I haven't gotten one reply yet and I want to get this done as this week is gonna be nuts at school)

The concentration of any solute in the buffer solution can be no more than 1.0M

Need to know:

- the mass or volume of each reagent used.
- Glassware
- How the reagents are combined.
- The volume of the buffer solution to be prepared.

I can use various solutions and solids provided by the lab such as 6M HCl, 6M HNO3, 6M HC2H3O2, etc. and solids NaC2H3O2, NaHCO3, NH4Cl, Na2SO3 etc..

(Note: There is a big long list of things I can use.)

I don't know how to start approaching this. I need a procedure before I go into the lab.

2007-04-08 14:38:44 · 2 answers · asked by Paulllll C 3

Imagine a universe in which the values of ms can be +1/2, 0, and -1/2. All other quantum numbers can take only the values allowed in our world and the Pualing Exclusion Principle applies.

How many unpaired electrons are there in fluorine?

2007-04-08 14:26:12 · 2 answers · asked by Anonymous

2007-04-08 13:42:01 · 1 answers · asked by Anonymous