Chemistry - March 2007

2007-03-07 19:29:07 · 1 answers · asked by gajani s 1

Hi im having difficulty remember what i have to do in order to work out the concentration of the acid and the sodium carbonate,

so far ive got:

Na2C03 = 106 g (RMM)
The amount of sodium is 2.65 g being used in distilled water to fill 250 cm^3 solution


and Na2SO4 = 142 g (RMM)
There is a total of 250 cm^3 solution for the acid.


where do i begin to even do this? i know that i need c = N0 of moles / volume.

2007-03-07 19:28:53 · 2 answers · asked by ? 1

What is meant by dual wave-particle nature of light?

2007-03-07 19:25:14 · 4 answers · asked by Whisper G 1

what are these? why are they important? how are they carried out?

2007-03-07 19:25:05 · 2 answers · asked by rocky 1

sorry i just wasnt born for chemistry but i know this is easy:

4.to two decimal places, what is the relative atomic mass and the molar mass of the lement potassium, K?

2007-03-07 19:18:27 · 5 answers · asked by Whisper G 1

I hope someone can answer this in layman's terms.

What do you mean by specific activity and how is it different from catalytic efficiency?

2007-03-07 18:23:37 · 3 answers · asked by doc_cliff 3

give answer in detail.

2007-03-07 18:08:25 · 2 answers · asked by rajesh karki 1

I don't understand the question : Which of the following mixtures gives a buffer with a pH less than 7.0? For CH3CooH, ka= 1.8 x 10^-5, and for NH3, kB= 1.8x10^-5.
The answer choices are:
a) 10 mL of .1 M NH3 + 10 mL of .1M HCL
b) 10 mL of .1 M Ch3CooH + 5.0 mL of .1 M NaOH
c) 10 mL of .1 M CH3COOH + 10 mL of .1 M NaOh
d) 10 mL of .1 M CH3Cooh + 10 mL of .1 M NH3
e) 10 mL of .1 M NH3 + 5mL of .1 M HCL


the answer is A, but i don't understand why..can someone help or explain it to me?thanks!

2007-03-07 18:06:22 · 3 answers · asked by :] 2

2007-03-07 18:05:23 · 2 answers · asked by i-sena 1

is there opium in the regular poppys, like can any house hold poppys be turned into opium? And if so why are poppys even legal?

2007-03-07 17:57:17 · 3 answers · asked by George 2

Choose those statements that are true about the two best resonance structures for the molecule H−C−N.

a) One resonance structure has eight valence electrons and the other has ten valence electrons

b) The best resonance structure has a double bond between the carbon and nitrogen atoms

c) Both resonance structures have a single bond between the carbon and hydrogen atom

d) The best resonance structure has a triple bond between the carbon and nitrogen atoms.

e) The best resonance structure has zero charge on nitrogen

2007-03-07 17:49:36 · 2 answers · asked by Pretty Girl 1

would the reaction of methyl salicylate and ethanol not harmful to the skin? is there a restriction or limitation when using both chemicals ( in a final formulation such as liniment )for the skin?
what would be the toxic substances in reacting such compounds?

2007-03-07 17:30:12 · 2 answers · asked by liryc 1

I've tried and tried, but I just can't seem to get this...Please help!

The problem:
4Fe+3O3--->2Fe2O3

An iron nail with a mass of 2.7 g was left to rust. 47% of the iron rusted.
a.) Calculate the mass of iron (III) oxide formed.

b.) Calculate the final mass of the rusty nail.

2007-03-07 17:15:48 · 4 answers · asked by .Cami.B. 2

2007-03-07 17:15:16 · 2 answers · asked by Anonymous

A solution is prepared by dissolving 1.6 g of SrCrO4 in 100. mL of hot water. SrCrO4 dissolves according to the equation

SrCrO4 -> Sr 2+ + CrO4 2-

Should a precipitate form if the solution is cooled to 25 C? Assume that a negligible change in volume occurs during the process. (Ksp=3.6 x 10^-5)

2007-03-07 17:13:37 · 2 answers · asked by Anonymous

It takes such a high temperature to break the ionic bond when salt is heated, but in water, the ions separate easily, yes? Why is that? Why does the Na Cl still have the properties of salt when the Na and Cl ions are separate? I guess I thought that the NaCl was just in smaller clumps, but still bonded...

2007-03-07 17:04:16 · 4 answers · asked by hpagliughi 1

The gram molecular mass of CO2 (The two is put below the "O") is the same as the gram molecular mass of:

A. SO2 (2 is below the "O" letter)
B. CO
C. C2H6 (Both numbers below the letters)
D. C3H8 (Both numbers below the letters)

2007-03-07 16:51:45 · 6 answers · asked by Kevin Lee 1

A solution is prepared by dissolving 1.6 g of SrCrO4 in 100. mL of hot water. SrCrO4 dissolves according to the equation

SrCrO4 -> Sr 2+ + CrO4 2-

Should a precipitate form if the solution is cooled to 25 C? Assume that a negligible change in volume occurs during the process. (Ksp=3.6 x 10^-5)

2007-03-07 16:51:08 · 1 answers · asked by Anonymous

Concentration of products is greater than the concentration of reactants,
Concentration of products is less than the concentration of reactants,
Rate at which products are formed is greater than the rate at which reactants are formed.
Rate at which products are formed is the same as the rate at which reactants are formed.

2007-03-07 16:21:43 · 2 answers · asked by Xquisite Shawtey 1

1. The Solvay process for the manufacture of sodium carbonate involves the following reactions:
NH3(g) + H2O(l) + CO2(g)-(arrow) NH4HCO3(aq)
NH4HCO3(aq) + NaCl(aq)-(arrow) NH4Cl(aq) + NaHCO3(s)
2NaHCO3(s) -(arrow) Na2CO3(s) + H2O(g) + CO2(g)

Calculate the masses of ammonia and sodium chloride required to produce 150.0kg of pure anhydrous sodium carbonate.

2. A 2.750g sample of zinc carbonate was treated with a solution containing 0.0500 moles of hydrochloric acid.
ZnCO3(s) + 2HCl(aq) -(arrow) ZnCl2(aq) + H2O(l)+ CO2(g)
Find the
a) limiting reactant
b) mass of carbon dioxide produced
c) mass of zinc chloride that could be recovered
d) mass of remaining reactant

Thanks for helping. Please show working and explain it to me if possible. Thanks so much!

2007-03-07 16:18:20 · 1 answers · asked by Anonymous

what are the major community problems brought by chemical reactions?and what are those reactions?? 10 points for the most answers!!

2007-03-07 16:16:47 · 1 answers · asked by Anonymous

1: The equation from the combustion of hexane is:
C6H14(g) + 19/2O2(g)-(arrow) 6CO2(g) + 7H2O(g)
Calculate the number of moles of
a) CO2 produced in the combustion of 1.50moles of hexane
b) H2O produced in the combustion of 0.25moles of hexane
c) O2 consumed in the combustion of 0.40 moles of hexane

2: Rewrite and balance the following equations:
a) KHCO3(s)-(arrow) K2O3(s) + H2O(g) + CO2(g)

b) NaOH(aq) + H2SO4(s) -(arrow) Na2SO4(aq) + H2O(l)

c) Na(s) + H2SO4(aq) -(arrow) Na2SO4(aq) + H2(g)

d) Hg(l) + O2(g) -(arrow) HgO(s)

e) Fe(s) + Cl2(g)-(arrow) FeCl3(s)

f) Fe2O3(s) + H2(g)-(arrow) Fe(s) + H2O(g)

3: When 10.650g of impure anhydrous potassium carbonate was reacted with excess dilute nitric acid, 3.150g of carbon dioxide was produced.
K2CO3(s) + 2HNO3(aq)-(arrow) 2KNO3(aq) + H2O(l)+CO2(g)
Calculate:
a) moles of potassium carbonate in the impure sample
b) percentage purity of the potassium carbonate sample

Thanks for helping me. Please show working.

2007-03-07 16:10:34 · 2 answers · asked by Anonymous

14 mg of a certain protein was dissolved in water to make a solution of 2.50 mL at 26C. If the osmotic pressure is 1.35 torr, what is the molecular mass of the protein?

To enter an answer in scientific notation use an e




6.022 x 1023 = 6.022e23



1.340 x 10-8 = 1.340e-8

Any help would be greatly appreciated!!!!!!!

2007-03-07 16:01:46 · 2 answers · asked by nietzsche 1

I need help please with these...Please explain it to me if possible...

1: Write balanced chemical equations for the following reactions:
a) potassium metal is added to water forming potassium hydroxide solution and hydrogen gas

b) copper metal is heated in oxygen gas to form copper (II) oxide

c) ammonia gas reacts with chlorine gas to form nitrogen and hydrogen chloride gases

d) solid potassium chlorate is heated and decomposes to produce solid potassium chloride and oxygen gas

e) lead nitrate solution reacts with sodium sulfate solution to produce sodium nitrate solution and solid lead sulfate

(note: this isn't multiple choice)

2: Write in words what is meant by the following equations (mention moles and subscripts).
a) 2Pb(NO3)2(s) -(arrow) 2PbO(s) + 4NO2(g) + O2(g)

b) NH3(g) + 5/4O2(g) - (arrow) 3/2H2O(g) + NO(g)

Thankyou for helping me.

2007-03-07 16:01:37 · 3 answers · asked by Anonymous

2007-03-07 16:01:26 · 2 answers · asked by deidre m 1

2007-03-07 16:00:42 · 3 answers · asked by Anonymous

The minimum energy required to break the oxygen-oxygen bond in O2 is 495kJ/mol. What is the longest wavelength of radiation that possesses the necessary energy to break the O--O bond? What type of electromagnetic radiation is this?

Please hlep me with this. I know that you have to convert energy to wavelength, but i don't know how or what ot do to convert to a single instead of a bond.

2007-03-07 16:00:15 · 1 answers · asked by shane200388 1

Calculate the wavelengths of the n=4 ----> n=1 and n=4 ----> n=3 transitions and indicate which regions of the spectrum these transitions would occur.

2007-03-07 15:56:36 · 1 answers · asked by shane200388 1

2007-03-07 15:47:03 · 1 answers · asked by AzNgRiMrEaPeR 1

Rate of the forward reaction is greater than the rate of the reverse reaction,
Rate of the reverse reaction is is greater than the rate of the forward reaction,
Concentration of the reactants reaches zero OR
Concentration of the products remains constant.

2007-03-07 15:37:51 · 2 answers · asked by Xquisite Shawtey 1