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Anne Marie Helmenstine, Ph.D.

Chemistry Questions & Answers

By August 7, 2013

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Know the answers to common chemistry questions! (Getty Images)Are you naturally curious about the world around you? If so, I bet you have lots of questions. Here are some common chemistry-related questions, complete with answers: Do you think you have all the answers? Try the 20 Questions Chemistry Quiz!

Comments

March 6, 2009 at 12:28 pm
(1) barb says:

how many grams of Na&Cl do I need to make 28 grams of NaCl?

February 14, 2011 at 2:42 am
(2) Viet Nam says:

Na: about 11gram
Cl : about 17 gram

August 3, 2011 at 3:15 am
(3) kawsarsajib says:

na=11 and cl=17 will make 28 grams of nacl

September 5, 2011 at 2:22 am
(4) nethmi says:

nice questions,are u a chemistry teacher???

May 11, 2009 at 6:00 pm
(5) Terry says:

how does the presents of impurities affect the boiling point of a liquid

October 7, 2010 at 8:06 am
(6) Isaac says:

you have to specify which impurities. But in general impurities increase boiling point and lower freezing point.But then, it depends on the impurity

October 29, 2010 at 4:04 am
(7) vee knight says:

it elevates the Boiling point of the substances

September 29, 2011 at 4:54 pm
(8) katelyn says:

what elevates at boiling point?

April 5, 2011 at 1:10 pm
(9) DOZIE ALISAH says:

IMPURITIES WOULD ALWAYS INCREASE THE BOILING POINT OF A LIQUID. THIS IS BECAUSE MORE NON-LATENT IS GOING TO BE ABSORBED BY THE IMPURITY AND THUS, THE TEMPERATURE [BOILING POINT WOULD BE INCREASED.

May 5, 2011 at 11:29 pm
(10) kumar saurabh says:

when non volatile substance dissolved in solvent the boiling point of solution is increased due to colligative property.

July 27, 2011 at 7:12 am
(11) adeoye eniola says:

when there are impurities in a liquid it increases the boiling point

May 12, 2009 at 8:18 am
(12) mekhla trisal says:

171 gm of cane sugar is dissolved in 1litre of water. what is the molarity of solution

May 5, 2011 at 11:25 pm
(13) kumar saurabh says:

the molarity of 171 gm sugal solution in one litre is m/2

May 15, 2009 at 4:11 am
(14) Ahmed says:

how can i determine the concentration and purity of an oxalic acid sample?

June 18, 2009 at 9:26 am
(15) winnie alivia says:

can you demonstrate the presence of some of the elements like carbon, hydrogen and other elements such as oxygen, nitrogen, halogens, sufur and phosphorous in a few organic compound and the type of chemical bonds present.

July 11, 2011 at 9:55 am
(16) vir mel says:

by using IR spectra one can identify the functional groups present in the compound and using H NMR and C NMR one can suggest the hydrogen and carbon framework

June 22, 2009 at 5:50 am
(17) dileep kumar says:

from where we get mercury

July 23, 2009 at 2:43 pm
(18) Lindsey says:

Complete this sentence: The molecules of different samples of an ideal gas have the same average kinetic energies, at the same ________.

March 7, 2011 at 10:58 am
(19) hedison says:

the same temperature

May 16, 2011 at 11:05 am
(20) might says:

u must lean how to tackle chemistry

April 2, 2011 at 1:46 pm
(21) charles says:

temperature and pressure

June 26, 2011 at 7:41 pm
(22) Alisa says:

Properties of metals

May 5, 2011 at 11:32 pm
(23) kumar saurabh says:

temperature

August 13, 2009 at 6:13 pm
(24) Carlton says:

Does mixing synthetic oil and pure oxygen present the same spontaneous combustion danger as does hydrocarbon based oils and pure oxygen?

September 1, 2009 at 2:13 pm
(25) Disulfide Scrambled says:

What is the relationship between redox potential and pH? Why would a disulfide be reduced with increase pH?

September 16, 2009 at 3:07 pm
(26) Cynthia says:

Use delta H degrees and Delta S degrees to find Delta H and Delta S for S(s)+O2 (g) —-> SO2(g) and use delta H and Delta S to find delta G at 25 degrees celcius>?

October 7, 2009 at 9:25 am
(27) devesh says:

i want to make a gas sensor for co2 based on electrochemistry. So i want to know that how can we genrate potential difference with co2? like by dessolving it in to a liquid and then measure the potential difference and how will i measure the potential difference?? please give me a reply as soon as possible.

October 8, 2009 at 6:28 am
(28) sadaf says:

i do not understand what is chemical equation

May 4, 2011 at 9:12 am
(29) michael says:

name given to a particular equation

September 26, 2011 at 10:23 pm
(30) Vladimir says:

That is a very intersting question. Is it rhetorical?

October 13, 2009 at 12:13 pm
(31) samrat singh says:

what happen when we add sulphuric acid in water and water in sulphuric acid?

July 21, 2011 at 6:45 am
(32) dammy says:

u can add sulphuric acid to water,but cannot add water to sulphuric acid to avoid chemical problem

October 13, 2011 at 1:41 pm
(33) ugama albert says:

acid is added to water not water to acid to avoid acid bath because acid splash occur when water is added to acid instead of the reverse

October 28, 2011 at 1:03 pm
(34) ashhad says:

u can not add water into H2SO4 because it has great affinity for water .thus water will turn to gas ……………

November 14, 2011 at 6:44 am
(35) bhavisha says:

we have to add sulfuric acid to water as water to sulfuric acid is a exothermic reaction and it will produce energy.

October 16, 2009 at 11:23 am
(36) mohamed abdulahi says:

what the number of molecules in 6.3g of sulphurdioxide gas

October 13, 2011 at 1:34 pm
(37) ugama albert says:

the acid splashes when water is added which is dangerous. as a chemist you add acid to water not water to acid.

November 4, 2009 at 12:51 pm
(38) lisa says:

i thought these questions were rather awsome for my project

November 4, 2009 at 12:53 pm
(39) carol says:

whats my name

November 21, 2011 at 6:10 am
(40) chocolove says:

Carol……..or maybe something else

November 21, 2011 at 6:13 am
(41) chocolove says:

such an idiot to post questions like this

November 10, 2009 at 2:32 pm
(42) Nuno says:

What is a fossil fuel?

November 30, 2009 at 2:20 pm
(43) Ashley says:

Why are people such idiots? They came to this site obviously for answers to their questions- ligitament questions, yet they ask stupid nonsense like, “What’s my name?”. What on Earth kind of question is that?! People who try to post idiotic crap on an ANSWERS website should be denied access to this site and any others all together.

July 30, 2011 at 11:54 pm
(44) ancl says:

yeah thats right…

October 29, 2011 at 5:38 am
(45) ugama albert says:

thats hw u know people dat are not ready to learn

December 17, 2009 at 12:42 am
(46) m.asgari says:

why Raderford select a gold sheet for exam not other metals?

September 27, 2010 at 7:09 am
(47) rodel grancioso says:

because gold is hard and solid element than other elements

December 21, 2009 at 2:58 am
(48) kiran says:

if acid is water soluable after doing hydrolyasis reaction of an ester. and during the workup in the acidifiaction , if acid is water soluable then how to recover the pure acid which will be free from the sodium chloride.

December 22, 2009 at 12:39 am
(49) Aniruddha says:

When electrolysis of aqueous NaCl is done,why the hydrogen is evolved at cathode instead of sodium(Na)?

September 8, 2010 at 11:05 pm
(50) olugbade hammed says:

hydrogen is evolved at the cathode because it will discharge in prefrence of sodium due to there position in the electrochemical series

December 28, 2009 at 2:58 pm
(51) Ahmed says:

Is Aspirin considered from Acids class or from Esters ?!
thx in advance … =]

October 1, 2010 at 6:55 am
(52) Sanjivani says:

from acid class

January 14, 2010 at 2:46 am
(53) udoka says:

udoka is boy who likes chemistry, but dont know it, but have interest in it. how can i lean it. please help me.

November 21, 2011 at 6:12 am
(54) chocolove says:

Always think that you can do it……dont have a positive thought

November 21, 2011 at 6:14 am
(55) chocolove says:

I am sry… i meant 2 say negative thought…..rly rly sry

January 14, 2010 at 8:16 pm
(56) Bob says:

what is an action unit?

January 19, 2010 at 11:44 am
(57) Muhammad Ahmad Islam says:

What is the trend across the Period Of ionistaion Energy ????

Explain Your Answer .. !!

January 23, 2010 at 4:35 pm
(58) john myers says:

what reaction do peroxides have with esters?

February 3, 2010 at 4:51 pm
(59) Chemi Cha says:

how can i fusion talc stone ? ” magnesium silicate ?

February 9, 2010 at 6:23 am
(60) della.quest says:

(a)Why do we classify elements?

(b)What were the two criteria used by Mendeleev in creating his Periodic Table?

(c)Why did Mendeleev leave some gaps in his Periodic Table?

(d)In Mendeleev’s leave Periodic Table, why was there no mention of Noble gases like Helium, Neon and Argon?

(e)Would you place the two isotopes of chlorine, Cl-35 and Cl-37 in different slots because of their different atomic masses or in the same slot because their chemical properties are the same? Justify your answer

February 15, 2010 at 3:11 pm
(61) danial says:

how we prepare alcohol from carbondioxide?
please reply me as soon as possible.Thanks

February 17, 2010 at 9:10 am
(62) saima says:

why conjugate acid is stronger than weak acid?

February 23, 2010 at 1:45 pm
(63) Loujayne makboul says:

See miss gave us puzzles on Using different solvents and i got a puzzle like this
nrshvai,rufit cejui,abll nipot kin,tehsm,rcth rooil nehtae, iwhet iistrp and otan cee so if u found it plzzzz……. tell me the answer it’s urgent I nee
d to get the answers by tommorow

April 9, 2010 at 2:19 pm
(64) Janielle says:

What is the difference between the product of carbon-12 reacted with chlorine and carbon-14 reacted with chlorine?

September 28, 2011 at 5:18 am
(65) Obalade tunde says:

Preparation of aluminium chloride

April 11, 2010 at 11:07 am
(66) DORA says:

A soluble chloride x react with a liquid y on heating to give gas z which turns moist litmus paper red and fumed in moist ,identify y and z,give 1 chemical test 2 confirm dat x is a chloride.Its urgent please i need the answer b4 2morrow my ……….thanks

April 12, 2010 at 9:29 pm
(67) kayla says:

i wonder what would happen if you mix up chemicals all together….????????

May 4, 2011 at 9:17 am
(68) michael says:

it is dangerous to mix chemicals eg do nt add water to acid it can expose

April 18, 2010 at 3:40 am
(69) maged ahmed says:

what is the chemical structure of solution of denige???

April 19, 2010 at 1:42 pm
(70) Sami says:

Hi,
Why doesn’t water denature proteins?
Protein denaturation by ethanol is explained by the formation of hydrogen bonds between the ethanol and certain aminoacids which breaks those formed between two aminoacids so why isn’t the same possible for water?
(I even considered the hydrophobicity of proteins…proteins are hydrophobic because they are -mostly- apolar and water is polar…..but the same can be said about ethanol…it is polar -less than water but still polar-)
Thank you.

April 23, 2010 at 7:56 am
(71) Hassan says:

What is the colour of the solution around the cathode,during the electrolysis of a mixture of Sulfuric acid and universal indicator?

September 1, 2011 at 12:24 am
(72) werwe says:

should be bluish

May 4, 2010 at 8:24 am
(73) joelbenoit says:

why during the transition temperature bw rhombic sulfur and monoclinic sulfur the other sulfur are not involved

May 9, 2010 at 9:53 am
(74) emily says:

when soap dissolves in water the sodium ions and the stearate ions becoms separated from eachother. which of these ions remain in solution regardlessb of wheather the water is hard or soft?

June 3, 2010 at 9:47 am
(75) ivonne says:

radio waves travel at the speed of light, which is 3.00×10^8 m/s. How many kilometers will radio messages to outer space travel in exactly a year? How would I solve this problem?

June 4, 2010 at 4:00 am
(76) bhavana says:

how can we learn chemistry easily

June 5, 2010 at 10:54 am
(77) adarsh says:

what happens if anhydrous copper sulphate and hydrated copper sulphate are dissolved in water ?

June 5, 2010 at 10:17 pm
(78) Amy says:

Can someone help me come up with the equation to use for this problem?
Calculate the volume of H2(g) at 273K and 2.00atm that will be formed when 275mL of 0.725M HCl solution reacts with excess Mg to give hydrogen gas and aqueous magnesium chloride.

June 14, 2010 at 3:48 pm
(79) zulkifl says:

when and how does the normality and molarity of an ionic solution become equal?

June 15, 2010 at 5:39 am
(80) Tayto says:

is reaction of ethyl aceto acetate with beta-halo ester possible? and what is the product?

June 21, 2010 at 2:55 pm
(81) anitha says:

which is called queen of drugs???
i need answer must

June 21, 2010 at 2:57 pm
(82) anitha says:

where we get mercury?

June 23, 2010 at 2:03 pm
(83) shakeel haseeb says:

why d block elements are called as outer transition elements and f block elements are called as inner transition elements?

July 5, 2010 at 4:00 pm
(84) mustafa says:

as we know that electrons repeal each other because they having negative charge so and we also know that in atom there may be about 100 protons . why proton dose not repeal each in nucleus . if it repeal each other so why the nucleus dose not broken

August 24, 2010 at 12:07 pm
(85) farisya says:

why are the gases more easily compressed than liquid??

October 29, 2010 at 8:38 am
(86) lina says:

Write the scientific term:
1 It is produced on adding MgO to water (…………)
2 A gas produced in the previous reaction (………….)

October 29, 2010 at 12:07 pm
(87) lina says:

what are the differences between metals and non-metals?

October 31, 2010 at 5:35 pm
(88) lore says:

what are the substances that will produce a blue precipitate when mixed in aqueous solution.write an ionic equation for that.here are the substances magnesium carbonate, cupper sulphate, potassium iodide, ammonium chloride, potassium hydroxide, dilute hydrochloric acid, hydrogen sulphide, silver nitrate and barium chloride

November 14, 2010 at 5:40 am
(89) Gbohun says:

What does it means by “chemistry of the earth”.

November 3, 2011 at 5:45 am
(90) ugama Albert m says:

chemistry of the earth means the chemical condensation resulting to earth formation.

November 17, 2010 at 3:32 pm
(91) Kelly says:

How would the calculated specific heat be affected if the metal cools before it is transferred to water? Higher, lower, unaffected?

November 29, 2010 at 9:08 am
(92) sudheer says:

plz briefly explain (lab experiment)determination of percentage of copper in brass plz send each step explanation and viva voce

December 10, 2010 at 10:49 pm
(93) Subodh gaikwad says:

very good
by what name chenestry disover

December 18, 2010 at 1:24 pm
(94) ADAM says:

Select all foods in which the sulfur is taken in form usable for human organism:

curd (cottage)
water
mineral sulfates, eg. sodium sulfate
meat
none of these answers

December 27, 2010 at 10:59 am
(95) wendy says:

Please help me answer this. I’ve understood everything else so far except this stuff:
Determine the mass of carbon monoxide that is produced when 45.6g of methane CH4 react with 73.2g of oxygen gas O2. The products are carbon monoxide, CO and water vapour H2O. You have to make a balance chemical reaction before you start. Then go from there. I cannot figure out how to balance or make a balanced equation to save my life

May 5, 2011 at 8:48 am
(96) moses says:

the products would be carbon dioxide with water. therefore the answer is CH4 + 2O2 -> CO2 + 2H2O

January 10, 2011 at 8:04 pm
(97) Syd says:

How is the compund h2o different from the elemants hydrogen and oxygen?

January 10, 2011 at 9:21 pm
(98) ChiChi says:

Hi im an intern at a science college and nxt week i have a to present a chemical reaction and i know that when you mix liquid ammonia with vinegar you get an explosion i want to kno how big of an explosion it makes because we have some things to put out a chemical explosion but i need to kno if i need to call a fire dep.

January 11, 2011 at 3:58 pm
(99) Ama says:

once formed crude oil becomes trapped in rock such as sandstone . why doescrude oil becomes trapped in sandstone.

January 12, 2011 at 1:12 pm
(100) Megan says:

What’s the chemical formula for ether menthol?

February 1, 2011 at 10:24 pm
(101) jjm says:

a correct group member of the state legislature receives a kick back from a lobbyist grouyp that wishers to defeat the flouride measure. this meber mandates that all flouride soloutionbe boiledfor 30 minutes before being used o test toxicity. now will this affect the test?

February 2, 2011 at 7:33 am
(102) Nabin says:

Answer—Free Radical and its mechanism in halogenation in alkane

February 8, 2011 at 4:18 pm
(103) debby policy says:

what is the state of matter of sun and fire

February 24, 2011 at 6:40 am
(104) Geeta khatri says:

Mercury is metal but why it is very soft?

February 24, 2011 at 6:46 am
(105) Geeta khatri says:

According to law of conservation of mass. Mass is neither created nor gain but when we boil the milk more more it will change in the type of sweet . Then the mass of sweet is less then milk why it happens? It means that law of conservation of mass is wrong.

February 24, 2011 at 6:51 am
(106) Geeta khatri says:

According to the law of conservation of mass no mass gain destroyed . But when we boil milk more and more at least it changes in the type of sweet . then why mass of sweet is less than milk .

April 5, 2011 at 1:33 pm
(107) DOZIE ALISAH says:

when you boil a liquid it looses some of its matter through evaporation. this accounts for the loss of mass

February 24, 2011 at 6:59 am
(108) Geeta khatri says:

Gold is metal. But why it is very expensive from all metal.

May 5, 2011 at 11:40 pm
(109) kumar saurabh says:

gold is rare metal as well as it is very unreactive so it is to pricious

February 25, 2011 at 10:37 am
(110) Geeta khatri says:

what is the chemical formula of petrol?

March 12, 2011 at 4:56 am
(111) grellian says:

Hello,
I was wondering what the name of the ester derived from Salicylic Acid + Benzoic Acid would be? Salicyl benzoate?

March 13, 2011 at 8:06 pm
(112) kathy1060@yahoo.com says:

what element mixes with H20 and p;roduces sulferiic aciid?

March 31, 2011 at 6:29 am
(113) christy says:

i love chemistry so such that i read it bt i dont seem to understand it every time i study it, pls help me cos i dont know what to do and i dont want to give up cos i’m a science student and i really need chemistry for my future course.

April 2, 2011 at 1:48 pm
(114) charles says:

pls don’t give up dat is chemistry 4 u

March 31, 2011 at 6:43 am
(115) christy says:

what’s the highest volume of alcohol?

April 1, 2011 at 3:36 am
(116) Janice says:

sulfur+charcoal+?=what?
What-can-the-unknowns-be?

May 7, 2011 at 2:20 pm
(117) shantella says:

using the following equation unbalanced: please show your work

FeCl3 + K2C2O4 –> K3[Fe(C2O4)3] + KCl

What is the theoretical yield in grams of K3 K3[Fe(C2O4)3] if 7.39g of irron (III) chloride is used and potassium is present in excess.

May 27, 2011 at 2:34 am
(118) rohit verma says:

these are some mole concept question hope you all will help

1. 3 g of a salt of molecular weight 30 is dissolved in 250 g of water.calculate the molality of the solution.
2. how many molecules of co2 are contained in one litre of air if the volume content of co2 is 0.03% at NTP
3. how many liters of liquid CCL4(density=1.5 g/cc.) must be measured out to contain 1×10^25 CCL4 molecules
step by step please

July 7, 2011 at 9:18 pm
(119) jaja says:

Is there a direct reaction of hydrogen gas and oxygen gas to produce water?

July 17, 2011 at 12:48 am
(120) light says:

What volume of 4.50M HCL can be made by mixing 5.65M HCL with 250.0ml of 3.55M HCL? Calculate.

July 17, 2011 at 4:56 am
(121) aaa says:

A 20cm3 sample of a gaseous alkene is completely burnt in oxygen. The total volume of the product is 80cm3. Which of the following represents the alkene?

A. ethene
B. propene
C. butene
D. pentene

July 21, 2011 at 5:54 am
(122) dammy says:

1. Multiple Choice: The triple bond between the carbon atoms causes acetylene, C2H2, to have which of
the following shapes?

August 23, 2011 at 1:51 am
(123) venkatesh babu says:

how to prepare 0.01N ethyl acttate

September 8, 2011 at 7:09 am
(124) clement says:

this answer site is not being very active,we need all the questions to be answered please,you guys should try to help us more……i want to defeat chemistry

October 23, 2011 at 2:23 am
(125) Srinath says:

how can we prepare sodium chloride solution by precipitation reaction?

October 29, 2011 at 6:16 am
(126) Jo says:

A object with a mass of 100g
compose of 2 materials X(99%) and Y(1%)
how many grams of material Y is in the object?

X:
molar mass: 250g/mol
density: 1.2g/cm3

Y:
molar mass: 150g/mol
density: 15g/cm3

Is this question solvable?
Thanks~~

November 2, 2011 at 9:20 pm
(127) lost says:

Right now I’m working on a lab and I’m totally stumped. I have an unknown salt (possibly a hydrate) and I need to figure out which it is. I’ve already determined my cation is Zn and I’m fairly certain it is a hydrate (it loses mass when heated). I’m really having trouble understanding how to figure out what my anion is though. All I know is that all the salts are made of “common” compounds. Can anyone give me any helpful hints of what to check next?

November 26, 2011 at 1:05 pm
(128) Tarun Verma says:

how can we minimize nuclear waste disintegration? (except by lead chamber and dump and throwing in Mars or in antartica).can a CNT(carbon nanotubes) chamber help in minimizing radiations?

December 12, 2011 at 10:18 pm
(129) Joey says:

a 48.90 g sample of liquid lead at 576.0 oC is poured into a mold and allowed to cool to 21.0 oC. How many kJ of energy are released in this process?
The following information is given for lead at 1atm:
boiling point = 1740oC Hvap(1740oC) = 858.2 J/g
melting point = 328.0oC Hfus(328.0oC) = 23.00 J/g
specific heat solid= 0.1300 J/goC
specific heat liquid = 0.1380 J/goC

December 23, 2011 at 12:23 pm
(130) kankam yeboah kofi says:

what is rate of a reaction?
and state the collision theory

January 2, 2012 at 9:06 am
(131) wit-ful-thought says:

why does the m.p of nacl increased when we add cacl2 in it?

January 15, 2012 at 5:29 am
(132) jai says:

Sir how to prepare silver nitrate solution or salt from pure silver and nitric acid.Can u told me other method to prepare agno3 salt beause when we do tritate chloride against silver nitrate than end colour dont finding with him plz short out the problem

January 18, 2012 at 8:59 pm
(133) marisol guzman says:

what are the compounds found in methane

January 24, 2012 at 5:38 am
(134) Nitin says:

Could you please suggest me any organic solvent with lewis acidity………………….

January 26, 2012 at 2:42 am
(135) AMIT says:

ACETYLATION OF ORTHO HYDROXY BENZOIC ACID WHICH HYDROGEN WILL BE ATTACKED FIRST,
?

January 30, 2012 at 10:04 pm
(136) freddy says:

if gold has a value of $58.54 per gram, what is the value of a cubic foot of gold?

February 13, 2012 at 5:48 am
(137) Samuel says:

15cm3 of hydrogen are sparked with 10cm3 of oxygen at atm pressure in eudiometer. What is the total volume of the residual has at room temperature?

March 10, 2012 at 7:24 am
(138) Sonal says:

With strong base in a burette and strong acid in the conical flask, which indicator will be preferred??

March 15, 2012 at 11:39 pm
(139) rama devi says:

what is E Z configaration

and what is R S configaration

what is meant by isomerism

March 21, 2012 at 9:09 am
(140) Michael says:

State three differences between a crystal and an amorphous substance?

March 21, 2012 at 9:13 am
(141) Michael says:

What is surface tension?

March 30, 2012 at 3:49 am
(142) Arya says:

what is the difference between 3Dmovie and all the real things ?
(real things are 3D)

April 3, 2012 at 4:28 pm
(143) Jannja says:

What volume of a 15.6M HCI solution is required to prepare 500mL of 5.5M solution?

April 7, 2012 at 5:28 pm
(144) George says:

how many isotopes does plutonium have TODAY ???

April 12, 2012 at 5:23 am
(145) O-dhapor says:

@jannja,CiVi is equal 2 CfVf. Use it guy it will giv u 176.28ml

April 16, 2012 at 9:26 am
(146) alexia says:

element x and y have electronic configuration of 2,6 and 2,8,2 respectively when they combine, the formula of the compound formed is

April 18, 2012 at 11:26 am
(147) maleeha says:

why is ozone present as alayerin atmosphere & not like oxygen which is lighter?

April 23, 2012 at 9:20 pm
(148) Char says:

How does a difference of 1 pH unit change in terms of the concentration of H+?

April 25, 2012 at 2:38 am
(149) saqib says:

which of the element have the longest atomic radius

May 1, 2012 at 2:01 am
(150) zeeshan says:

why the e/m value of cathode rays is same for all the gases?

May 3, 2012 at 12:10 pm
(151) saumya says:

what is chemical

May 4, 2012 at 5:18 am
(152) Maryam says:

why water is a liquid and hydrogen sulphide is a gas at room temperature?

May 7, 2012 at 4:20 pm
(153) panda says:

After extracting a substance, I would like to use an evaporation technique to solidify the extraction. Does the substance I’m extracting need to have certain properties to be able to crystalize? Or do I need hydrochloride for crystalization?

May 12, 2012 at 12:25 pm
(154) lucynjoroge says:

which is the catalyst used in laboratory preparation of hydrogen gas?

May 25, 2012 at 9:08 pm
(155) Sahara says:

1. A sample of carbon dioxide occupies a volume of 3.5 liters at 125 kPa pressure. What pressure would the gas exert if the volume was decreased to 2.00 liters?

2. 46 ml of O2 gas is collected over water at 25oC when the atmospheric pressure is 102 kPa. What volume of pure oxygen would this be at standard temperature and pressure? (standard pressure is 101.3 kPa)

3. One common rocket engine uses the following reaction:

7H2O2 (aq) + N2H4 (g) 2HNO3 (g) + 8H2O (g)

If the rocket engine contains 1500.0 g of H2O2 and an excess of N2H4, what volume of water vapor will be produced when the rocket fires up to a temperature of 540oC and a pressure of 1.2 atm?

4. The vapor pressure of water is 30.0 torr at 29oC. If a reaction at that temperature produces oxygen which is collected over water, what total pressure will have to be in the reaction vessel to ensure that the oxygen collected had a partial pressure of 567 torr?

5. Use Hesss Law to determine the rH for the combustion of liquid methanol (CH3OH)?n (Remember: complete combustion reactions require oxygen and always produce carbon dioxide and water).

6. What is the sign of rS for the following reaction?

NaHCO3 (aq) + HCl (aq) NaCl (aq) + H2O (l) + CO2 (g)

7. What is the rS for the following reaction?

H2O (l) + CaO (s) Ca(OH)2 (s)

Thanks!

June 6, 2012 at 11:27 pm
(156) priyanshi garg says:

1 mole of a non ideal gas undergoes a change of state 92 atm,3 L,95 k)—–>4 atm,5L,245 k)wid a change in internal energy,del U=30 Latm.the change in enthalpy (del H) of the process in L-atm is?

June 24, 2012 at 1:28 pm
(157) Seeker says:

plz ans this…

June 29, 2012 at 9:51 am
(158) MANOJ M B says:

Why does hot water freeze faster than cold water?

July 4, 2012 at 12:09 am
(159) Utshav says:

hydrogen carries both the character of meal and non metal then why it is naot call it as a metalloid

July 10, 2012 at 9:57 am
(160) kp says:

I was told to make a solution and in the paper it reads as follows:
10 ml of .1 M NH2OH HCl -2 M HCl

Is it telling me to make the .1M NH2OH HCl in 2M HCl????

July 10, 2012 at 3:08 pm
(161) niyi says:

what the number of molecules in 6.3g of sulphurdioxide gas

July 13, 2012 at 11:47 am
(162) oyedunke says:

it a greet thing to some questions like what i have seen

July 17, 2012 at 6:22 am
(163) Soheil shabani says:

Hello.I am looking for chemical With water (saliva) to the reaction.And does not harm the body and the production of gas The effervescent tablets.
With respect

July 20, 2012 at 9:47 pm
(164) MCDRG says:

Flourine reacts with Hydrogen (H) and with deuterium (D) to form hydrogen flouride (HF) and deuterium flouride (DF) [deuterium is an isotope of hydrogen]. Would a given amount of flourine react with different masses of the two hydrogen isotopes? Does this violate the law of definite proportions?

July 31, 2012 at 9:31 am
(165) lekclef says:

what is the important of benzene base on medical line

August 3, 2012 at 3:00 am
(166) naresh says:

organometallic compund used as an antiseptic is;
(1) Ferrocene
(2)mercurochrome
(3) Trialkyl tin
(4) Azaferrocene

October 3, 2012 at 3:32 am
(167) ABHISHEK MISHRA says:

why Pb2 is placed in both group I and IIA???

October 17, 2012 at 10:36 pm
(168) Sandra says:

What is the for sodium chloride?

NaCl!!!!!!!!1

October 28, 2012 at 2:45 pm
(169) Rory says:

Two isotopes of silver were found to exist in sample, silver-107 and silver-108. The relative atomic mass of silver is 108, what does this suggest about the abundance of each isotope in that sample?

November 4, 2012 at 11:53 am
(170) NAyAN says:

what is chirotopic center?

November 4, 2012 at 3:25 pm
(171) JenRo says:

Well preserved remais of now extinct wooly mammoths are entombed in the permafrost of Siberia. Scientistis hav conducted Carbon dating experiments on plant debris found inte stomachs of the mammoths. The Carbon -14 activity of the youngest mammoths were measured at 5.8 disintegration/min/gram of Carbon. How many years ago did the Siberian Mammoths become extinct? Living tissue has a C-14 activity of 15.3 distintegration/min/gram of carbon.

This is a real question from my Chem 400. I could really use some help.

November 19, 2012 at 8:27 am
(172) akash Mitra says:

i m a stdnt f Bsc chem. i jst want to kno ‘where chemistey meets eternity,determine GOD’ as THE CHEMIST “!

January 15, 2013 at 10:00 am
(173) chima says:

what is the relationship of half life with human life

February 10, 2013 at 1:40 pm
(174) sandyy says:

the hydrocarbon ethane undergoes complete combustion according to the following equation : 2CH+7O = 4CO + 6HO
what is the volume of oxygen is required to completely combust 5 dm3 of ethane ???

April 24, 2013 at 1:47 pm
(175) deepam vyas says:

oxidation no. Of a,b,c are 2, 5 ,and -2 respectively possible formula of compound is ?

June 5, 2013 at 10:52 am
(176) Erica says:

You are working for a large chemical company doing an inventory of their chemical stocks. You find a 40L cylinder in a storage room marked Oxygen (O2). The thermometer on the storage room wall is at 160C and the gauge on the cylinder reads 14.1atm. How many grams of oxygen gas should you record in the inventory for this cylinder? Round your answer to the nearest 1 gram. Don’t include units.

September 3, 2013 at 4:06 am
(177) jowarshdel says:

who discovered the element sodium chloride?im ah student from nueva vizcaya

October 24, 2013 at 3:31 am
(178) ALISHBA says:

GAS LAWS

November 11, 2013 at 11:45 pm
(179) sunny says:

what are super halogen……??

February 6, 2014 at 11:57 am
(180) Mark Isaac says:

Hypothetically speaking, could Oxygen combine with GABA (gamma-aminobutyric acid) in unstable Hydroxyl form?

Just as oxygen sticks to blood?

I know that Hydroxyl is present in space from comet tails, and the Hydrogen in that is solid and the oxygen is a gas.

GABA has also got repulsion polarity magnetism on one side, which would make it positive on the other side, which could in turn attract paramagnetic Oxygen.

Adding one oxygen atom on the positive side of GABA would make the total number 17 which is the number of the other side.

During Abiotic stress in plants, the plant releases a lot of GABA.

In the Brain GABA goes from neuron to glion to neuron and is generally transported around.

I feel like I’m missing some sort of technical term which disproves the possibility of this idea, I was just hoping you could shed some light on this for me.

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