Chemistry - August 2007

Okay so the problem is: A 8.746 gram mixture of calcium hydroxide and potassium hydroxide is exposed to an atmosphere of pure CO2. The mass of solid increases to a final value of 14.472 grams. Calculate the percentages of the individual solids in the original mixture, given that the following reactions occur.

Ca(OH)2 (s) + CO2 (g) ==> CaCO3 (s) + H2O (g)
KOH (s) + CO2 (g) ==> KHCO3 (s)


Thanks so much. I dont really need you to show me every detail of how to do it, but just the start of a basic idea of what I'm supposed to do would do fine. thanks again!

2007-08-16 17:18:06 · 3 answers · asked by Melody 2

2007-08-16 17:16:16 · 7 answers · asked by Anonymous

The maximum amount of N2H4 (hydrazine) that can be prepared from 14 grams of nitrogen and 28 grams of hydrogen by the reaction N2 + 2 H2 = N2H4 is ?
a) 16 grams
b) 28 grams
c) 32 grams
d) 42 grams
e) none of these values

2007-08-16 17:01:49 · 6 answers · asked by Pam 1

In one mole of C6H14O6 there are approximately how many grams of oxygen ?
a) 66
b) 96
c) 180
d) 36 x 1023
e) none of these values

2007-08-16 16:49:59 · 4 answers · asked by Anonymous

A) lithium does not exist in nature as a free element
B) the mass of lithium is the sum of the masses of the protons and electrons in the atom.
C) the mass of a proton is not exactly equal to 1 amu.
D) lithium has more than one isotope

2007-08-16 15:15:06 · 1 answers · asked by Anonymous

13. Heyrogen sulfide H2S is a weak diprotic acid. In a 0.1 M solution of the acid the specie that would be expected to have the highest conetration is
a. H2S
b. H2O+
c. HS-
d. S2-
e. OH-

2007-08-16 15:02:28 · 1 answers · asked by Kristin R 2

11. A 7.2 x 10^-3 M solution of acetic acid is 5.0% dissociated. In a 7.2 x 10^-2 M solution, the percentage of dissociation would be???
a. the same
b. >5%
c. <5%
d. zero
e. none of these

2007-08-16 14:58:26 · 1 answers · asked by Claire M 1

A student determins the mass of a metal rod to be 39.35 g. It is places to 10.00 mL of water, and water level rises to 15.00 mL. What is the density of the rod?

2007-08-16 13:38:37 · 6 answers · asked by Anonymous

Which from the following is the enthalpy change of formation of CO2

C(graphite) + O2 --> CO2 (Delta H = -393.5kJ/mol)

or

C (diamond) + 02 --> C02 (Delta H = -395.4 kJ/mol)

Is it anyone of them or do I have to obtain and average?

2007-08-16 12:09:57 · 1 answers · asked by }{3@T 2

Reaction is:

2NO(g) + O2 (g) --> 2NO2 (delta H = -114kJ)

Also it asked:

Using the relationship between free energy change, enthalpy change and entropy change for a reaction, explain why that reacttion is less energetically favoured at high temperatures.

Please help cause I neve gothang of these and this is summer HW so I can't ask my teacher. Thanks

2007-08-16 12:01:59 · 2 answers · asked by }{3@T 2

2007-08-16 11:50:45 · 1 answers · asked by }{3@T 2

Gallium consists of two isotopes of masses 68.95 amu and 70.95 amu with abundances of 60.16% and 39.84%, respectively. What is the average atomic mass of gallium?

2007-08-16 10:55:43 · 2 answers · asked by juggy joe 1

Can some one please help? Show balanced equaitions and cancellations.....

Problem #1:
Aluminum oxide is formed from the reaction of metallic aluminum with oxygen gas. How many moles of Aluminum are needed to form 3.4 moles of Aluminum oxide?
Hint: This is a simple ratio problem. Just use the molar ratio from the balanced equation. This was covered in 5.09. Mass is not involved.

Problem #2:
Determine the number of grams of NH3 produced by the reaction of 3.5g of hydrogen gas with sufficient nitrogen gas. (Check for diatomic elements).

Thanks for the help.....

2007-08-16 09:45:37 · 5 answers · asked by Anonymous

thanx

2007-08-16 09:35:54 · 3 answers · asked by Anonymous

thanx for every1 who helps me

2007-08-16 09:34:51 · 2 answers · asked by Anonymous

I found them very clean under microscope and very nice smooth touch, but how about some little ozone or O3 oxy?

2007-08-16 08:14:34 · 2 answers · asked by toodd 4

Mari is examining a sample of a fine white crystalline substance. which test will demonstrate that she is looking at a compound rather than an element?

A when placed over a Bunsen burner, the substance burns with a colored flame

B careful measurment reveals that the substance's melting point is 884 C.

C chemical analysis shows that the substance contains sodium and sulfur.

D The substance looks like table salt and Maria remembers that table salt is a compound with sodium in it.

2007-08-16 07:51:56 · 3 answers · asked by CHRIS 1

Im taking chem online and the book I have is awful. I dont understand reactions and how to predict them. Can anyone help me with this question. Thanks!

Predict whether a reaction is likely to occur for the following. If so, write the net ionic reaction.
a) MgBr2 (aq) + ZnSO4 (aq) 
b) BaS (aq) + CuSO4 (aq) 

2007-08-16 07:43:07 · 4 answers · asked by Karter 2

the electronic configuration of boron is 1s^2 2s^2p^1 so in the last layer is missing 5 electrons to fullfil to ...2p^6 and there would be 5 valency electrons. where am i wrong???

2007-08-16 07:19:49 · 2 answers · asked by Anonymous

are all aromatic compounds cyclic?

2007-08-16 07:18:15 · 8 answers · asked by Anonymous

The element copper is a lustrous red metal. The element oxygen is a coloress,oderless gass. In a laboratory expariment,which of these wouls demonstrate that fthey have formed compound

A the elements have combined a form a new substance that is black,crytallie solid.

B the elements are in diffenent rows on the periodic table.

c Each element appears to be unaffected when placed near a sample of a clear liquid

d both elements are present in a sample of a mixture.

2007-08-16 07:17:56 · 2 answers · asked by Anonymous

I have a bottle of Flintstones vitamins, and I stopped taking them for a while, and I just opened them and the vitamins all have little black specks on them. Is that a mineral oxidizing- iron, magnesium, zinc...?

2007-08-16 07:11:08 · 6 answers · asked by Anonymous

2007-08-16 07:06:11 · 6 answers · asked by Anne 2

Any help is appreciated, and needed.

1. What volume of 0.800M KOH is needed to neutralize 15.0mL of 0.65M H2SO4?

2. What is the molarity of sodium hydroxide if 38mL of the solution is titrated to the end point with 14mL of 0.75M sulfuric acid?

3. It requires 24.6 mL of Ca(OH)2 solution to neutralize 14.2 mL of 0.0140M HCH3COO. What is the concentration of the calcium hydroxide solution?

4. By titration, it is found that 12.4 mL of H2SO4 is required to neutralize 19.8 mL of 0.100M Ca(OH)2. What is the molarity of the H2SO4?

5. What is the volume of 0.120M Ba(OH)2 is required to neutralize 12.2 mL of 0.25M HCl?

Like I said, any help is appreciated, and needed. I have no hope of passing this class unless I get an understanding of this subject.

2007-08-16 04:23:10 · 3 answers · asked by Anonymous

I'm in physical science and we're talking about delta symbols, like for change and time and everything. So help? Thanks much.

2007-08-16 03:40:44 · 6 answers · asked by Bex 2

Magnesium Pho
sphate?
mg Po4
2 3 How did you get the numbers 2 and 3 i am confused
3 2

2007-08-16 03:08:52 · 8 answers · asked by matilda 1

2007-08-16 02:19:19 · 1 answers · asked by teokz2002 1

A balloon filled with 2l of hydrogen gas contains 0.18 g of H2.

(a) How many mol of H2 are there in the balloon ?
(b) How many molecules does it contain ?
(c) How many atom does it contain ?

DATA NA = 6.023 x 1023 mol 1
Please help me:0(

2007-08-16 01:11:51 · 4 answers · asked by kkmdjs 2

this question is related to chemistry

2007-08-16 00:58:19 · 2 answers · asked by aftabsaad s 1

I was just wondering what would happen

2007-08-15 22:51:12 · 17 answers · asked by mattyb1811 1