Wednesday
September 17, 2014

Posts by andy


Total # Posts: 817

chem can u check answer please
Which is NOT a chareteristic property of acids? A: react with carbonate to yield CO2 gas B: taste sour C: neutralize bases D; turns litmus red to blue E:reacts with metal to yield H2 gas I reckon its D because isnt it the other way around ? Blue to red ...not...red to blue Any...
May 23, 2010

chem can u check answer please
what is the hydrogen ion concentration of an aqueous solution with a pOH of 9.262? I got 5.47X 10 ^-10 is this correct? Thanks Andy
May 23, 2010

chem can u check answer please
the solubility of silver sulfate in water is 0.223%(w/v) at 35 degrees celsius.calculate the solubility product of this salt at this temp. I got 1.46 X 10^-6 M is this right please thanks Andy
May 23, 2010

Chem/science
what is the ph of 2.62 x 10 ^-2 M HBr solution? I get 5.94 is that right? thanks andy
May 23, 2010

Chem/science
What is the conjugate acid of HC5H6O4-?? Is it HC5H6O42-?? thanks andy...
May 23, 2010

Chemistry
Why can't benzene dissolve sodium chloride?
May 18, 2010

3rd grade
Ineed help with the synonyms and antonyms ex. perfect, frawless is this an antonym or synonym?
May 17, 2010

SCIENCE?CHEMISTRY***
Dr Bob each time i do a problem on this site I have to print out answer....is there any way you know how to save it to usb stick???? I cant for the life of me find a save feature... also how do YOU when you give us a link to a site ...make it appear in blue and all we have to ...
May 16, 2010

SCIENCE?CHEMISTRY***
thanks dr bob Andy
May 16, 2010

SCIENCE?CHEMISTRY***
Am using the inventory method at moment but am stuck on how fill i the inventory for __Agl+__Fe2(CO3)3--> __Fel3+__Ag2CO3 I think the brackets are throwing me Hows this element b4 after ------------------------------------ Ag 1 2 l 1 3 Fe 6 1 CO 3 3 I dont know if this is ...
May 16, 2010

SCIENCE?CHEMISTRY***
well done thanks... Andy
May 14, 2010

SCIENCE?CHEMISTRY***
an 56 Fe 2+ particle has how many protons neutrons amd electrons??? 56 2+ Fe Thanks Andy
May 14, 2010

SCIENCE?CHEMISTRY***
how many dozens of dust particles are in 2.45 g if each particle has a mass of 2.51 x 10^-4 grams...? I dont have a clue!!!!!! Thanks Andy
May 14, 2010

SCIENCE?CHEMISTRY***
thanks..... andy
May 14, 2010

SCIENCE?CHEMISTRY***
DR Bob, can you go thru the steps to work this out please.... how many grams of alcohol with a density of 0.900 g/cm ^3 (cm cubed) will have the same volume as 20.0g of mercury,with a density of 13.6 g/cm ^3 Do you have to find the volume of mercury first??? I know the answer ...
May 14, 2010

chemistry
thanks..andy
May 13, 2010

chemistry
The solubility of MnS was found to be 0.000963 g per 700 mL of water. Calculate the solubility product constant (Ksp) for MnS. MnS (s)=Mn2+ (aq) + S2- (aq)
May 13, 2010

chemistry
The solubility product constant (Ksp) for the dissolution of PbSO4 as represented by the chemical equation is 1.7x10-8. PbSO4 (s)= Pb2+ (aq) + SO42- (aq) Calculate the mass (g) of PbSO4 that dissolves in 1100 mL of water.
May 13, 2010

SCIENCE/CHEM
thanks so much....andy
May 12, 2010

SCIENCE/CHEM
Dr Bob Is it true that only TWO molecules of water are required to balance the equation for the reaction of HCL with Calcium Hydroxide.(calcium chloride is the other product....why??? Thanks andy
May 12, 2010

SCIENCE/CHEM
thanks.... andy
May 12, 2010

SCIENCE/CHEM
Dr BOB, Can you show me how to do the balanced equation please I am shocking at them Thanks AndyWhats the simple way to explain balancing equations so i get it please....because i am horrible at them... Thanks andy
May 12, 2010

SCIENCE/CHEM
the purity of zinc is to be determined by measuring the amount of hydrogen formed when a weighed sample of zinc reacts with an excess of HCL acid.the sample weighs 0.198 grams. what amount of hydrogen gas at STP will be obtained if the zinc is 100% pure? need a metric answer ...
May 12, 2010

SCIENCE/CHEM
thanks..... andy
May 12, 2010

SCIENCE/CHEM
the volume of a sample of gas is 650.ml at STP. what volumes will the sample occupy at 0.0degrees celsius and 950.torr??? is it 650.ml?
May 12, 2010

SCIENCE/CHEM
thanks so much ...andy
May 12, 2010

SCIENCE/CHEM
so 2 X4 ^2 = 32 so 32 is correct ....... thanks andy
May 12, 2010

SCIENCE/CHEM
thanks...andy
May 12, 2010

SCIENCE/CHEM
how many electrons can be contained in all orbitals with n=4??????
May 12, 2010

SCIENCE/CHEM
thanks ...will practice and practice and practice.....andy
May 12, 2010

SCIENCE/CHEM
I suck at balancing!!!! Sorry Dr BOb you will have to take me on a slow journey on this one....Thanks andy
May 12, 2010

SCIENCE/CHEM
when the following equation is balanced , what is the sum of the co-efficients? AL2(SO4)^3+Ca(OH)2-->Al(OH)3+CaSO4
May 12, 2010

science /chem
thanks so much....andy
May 12, 2010

science /chem
1.250X10^3 ....hows that???
May 12, 2010

science /chem
thanks I think I acn do that one now...Regards Andy
May 12, 2010

science /chem
1250.37986 rounded to four significant figures is ??????
May 12, 2010

SCIENCE/CHEM
thanks...... andy
May 12, 2010

SCIENCE/CHEM
aha....# of prot and electrons =35 same as atomic number. #of neutons=mass number - atomic number=44 neutrons... so 35 protons,44 neutrons and 35 electrons .....hows that???
May 12, 2010

SCIENCE/CHEM
does that narrow it down to 35 prot,79 neutrons and 35 electrons? Soory bit lost on electrons... Andy why was there two choices for mass number???
May 12, 2010

SCIENCE/CHEM
Bromine exists as a mix of bromine 79 and bromine 81 isotopes. an atom of bromine 79 contains: 35 prot.44.neutr.35 electrons 35 prot.and 35 electrons only 44 prot.44 elect and 35 neutr. 35 prot.79 neutr. and 35 electrons 79 protons 79 electrons and 35 neutr. which is correct ...
May 12, 2010

MATHS !!!
thanks..... andy
May 12, 2010

MATHS !!!
convert 3.22 mm into cm please
May 12, 2010

SCIENCE 1
Thanks so much I have always wondered
May 11, 2010

SCIENCE 1
Does a snails shell grow at the same rate as the snail?? HOW???
May 11, 2010

chemistry
Thanks Dr bob my brain hurts about this stuff as i try to memorise too much.... thanks for your advice and maybe one day it will all come clear and until then i am still waiting for my AHA...moment sorry till then i need help ....thats why god put brilliant and patient ...
May 11, 2010

chemistry
Dr bob can you help with my last question for tonights home work please A gas mixture consists of equal parts of methane(molecular weight 16.0) and argon (atomic weight40.0). if the partial pressure of argon is 26.6 kPa what is that of methane in the same units? 10.7 26.7 66.7...
May 11, 2010

maths
thanks so much
May 11, 2010

maths
which of the following statements is incorrect? 1 microlitre=10^-6 litres 1 megagram=10^6 grams 1 millimetre=10^3 metres 1 kilogram=10^3 grams 100 centimetres=1 metre thanks andy
May 11, 2010

CHEMISTRY
so its a trick question as the unwary would say that CH4 and Ar under ideal behavior would be the same and the answer would be 26.7....?? But its obviously worded to catch out the unwary about partial pressure questions? Finally i can rest and the answer is 66.7 NOT 26.7!!!!! ...
May 11, 2010

CHEMISTRY
ok so P ch4 = 13.67 kPa where do i go from there??
May 11, 2010

CHEMISTRY
a gas mixtuer consists of equal masses of methane(molecular weight 16.0) and argon (atomic weight 40.0) if the partial pressure of argon is 26.6 kPa, what is that of methane in the same units? 10.7 26.7 66.7 34.1 I am going with 26.7 Do you agree and why please Thanks Andy
May 11, 2010

CHEMISTRY
I am confused about this statement about water Which of the following is TRUE regarding water only covalent bonds are broken when ice melts (dont think so) all of the staements (A-D) are false energy must be given off in order to break down the crystal lattice of ice to a ...
May 11, 2010

biology
Non vasculaar plants are those that dont use a vascular system to transport fluids around the plant..such as moss Hope this helps
May 11, 2010

CHEMISTRY
although helium atoms do not combine to form He2 molecules is it fair to say that London dispersion forces (induced dipole forces)are what attract He atoms weakly to one another? The other choices are dipole-induced dipole forces Hydrogen bonding Ion-dipole forces dipole-...
May 11, 2010

CHEMISTRY
Wow great!!! thanks very muchyou are right when you look at the shape in the book...it actually becomes obvious Andy
May 11, 2010

CHEMISTRY
do you agree that HCL is the beast choice for a substance that has both dipersion forces and dipole-dipole forces ? The choices I have are : Br2 HCl H2 CO2 BCl3 HCL is the most sensible answer. Do you reckon so too? thanks andy
May 11, 2010

Chemistry
thank you so much for that wonderful chart Andy
May 11, 2010

Chemistry
That would be great if i could see the chart thanks Andy
May 11, 2010

Chemistry
Dr Bob Can you please confirm for me that only NH3 has a boiling point that does not fit the general trend from these choices NH3 PH3 SbH3 AsH3 many thanks andy I am picking NH3 because of the reason that the larger the compound the greater the boiling point Am I right with my...
May 11, 2010

science/chemistry
thanks andy
May 11, 2010

science/chemistry
Dr Bob Although helium atoms do not combine to form He2 molecules. is it true to say that He atoms are weakly attracted to one another from London dispersion forces (induced dipole forces) or is there another force at play? It cant be Hydrogen bonding(there is no hydrogen here...
May 11, 2010

CHEMISTRY!!/science
A mixture of CO2 and an unknown gas was allowed to effuse from a container. The carbon dioxide took 1.25 times longer than the unknown gas to escape.Which of the following gases could the unknown one be Choices A: Cl2 B: CO C: HCl D: H2 E: SO2 I am going B for this reason: ...
May 10, 2010

science/chemistry
Oh I see now that you explained it that way!!!! OOPS....sorry yes I took a stab in the dark.....One day I may get this stuff....its going to be a long trip....How do YOU remember all this??? My heads about to explode and I am too young to die!!!!!!!!
May 10, 2010

science/chemistry
Aha its actually A??? Correct???
May 10, 2010

CHEMISTRY!!
Which of the following is NOT a postulate of the kinetic molecular theory? A; the average kinetic energy of the particles is directly proportional to the absolute temp. B;the forces of attraction and repulsion between the particles are insignificant C:the moving particles ...
May 10, 2010

CHEMISTRY!!
Can someone check my answer please: Magnesium metal(0.100 mol)and a volume of aqueous HCL that contains 0.500 mol are combined to react to completion. how many litres of hydrogen gas (measured at STP) are produced choices: 4.42 11.1 22.7 2.27 5.53 I like 2.27... Is this right...
May 10, 2010

CHEMISTRY!!
I believe that you are right due to the conversion difference and the fact that none of the other answer are even remotly close !!! Thanks DR BOB
May 10, 2010

CHEMISTRY!!
Calculate the mass in grams of 2.74L of CO gas at 33 degrees celcius and 126.0 kPa I got 3.75 grams Is this right please Thanks
May 10, 2010

CHEMISTRY
Thanks Dr Bob You rock!!!! Andy
May 10, 2010

CHEMISTRY
Dr Bob Can you confirm please Given a cylinder of fixed volume filled with one mole of Ar gas,which of the following is CORRECT? (assume that all gases obey the ideal gas laws) A: if the cylinder temp. is changed from 20 to 25 deg.C the pressure will double B:a cylinder of ...
May 10, 2010

science
For the following reaction if the reaction temperature was increased would the equilibrium shift to the right or the left,not shift at all,or you cant answer the question because Keq is not given? 2SO3(g)<-->2SO2(g)+O2(g)..(deltaH degrees =198kj) Why???
May 10, 2010

chemistry
Thanks DR BOB, You had me worried for a second there!! Thanks for all your great help on this one Regards Andy
May 10, 2010

chemistry
Doess this mean I fluked the write answer?? Could you write it out as I have above please with your logical answers so I can go away and study if we are right..I am never comfortable not knowing I have the right workings Thanks andy
May 10, 2010

chemistry
Can you please check if I came up with the right answer for this please. A 4.30L container had 55.10 moles of N2O4 added to it. When equilibrium was established the concentration of N2O4 was found to be 1.69M.What is the Kc for the following reaction? N2O4(g)<-->2NO2(g) ...
May 10, 2010

chemistry
is the above equation balanced? 3CIO2-(aq)<-->2CIO3-(aq)+cl- if not how do you balance it (I suck at this) thanks Andy
May 10, 2010

chemistry
Dr Bob NO I dont know how too do Keq.. Can you give me some starts on this problem please.Thanks andy
May 10, 2010

chemistry
Write the equilibrium expression Qc for the following: 3CIO2-(aq)<-->2CIO3-(aq)+Cl-(aq) Choices: 3[CIO2-]/2[CIO3-][Cl-] 2[CIO3-][Cl-]/3[CIO2-] [CIO2-]^3/[CIO3-]^2[Cl-] [CIO3-]^2[Cl-]/[CIO2-]^3 I dont even know where to start with this one can you help please. Thanks andy
May 10, 2010

chemistry
DR BOB Can you check my answer at Monday may 10 2010 at 7:12 pm at Chemistry -andy(Page 2) I think I may have got it !!! Thanks andy
May 10, 2010

Intermediate Algebra
thanks
May 10, 2010

Intermediate Algebra
How would I figure out this math problem? (a video game was $49.95. The price dropped to $45.50. what was the percent of decrease.)
May 10, 2010

science
Dr bob, can you check my reply to chem question from andy thanx
May 10, 2010

chemistry
Dr bob, can you check out my theory on previous post....thanx Andy
May 9, 2010

chemistry
for the equilibrium H2+CO2<-->H2O+CO Kc=3.18 at 1106K. if each of the four species was initially present at 3.000M calculate the equilibrium concentration of the CO at this temperature..... OK I can get as far as equilibrium (final) H2O=3.000-x CO=3.000-xx H2=3.000+x CO2...
May 9, 2010

chemistry
Thanks Dr Bob, I am horrible at algebra.... But since reading your reasoning I have now got ammunition to be able to reason out the answer....I will try harder and study more.. Thanks for all your advice it was great Andy
May 9, 2010

chemistry
Dr BOB, How this (3+0.844)^2/(3-0.844)^2=3.18(rounded) sqrt(3.18)=1.7832 So there fore answer=0.844 which is one of the answers! Am I on the right track? Andy
May 9, 2010

chemistry
DR Bob, If I plug in 0.01 for x then the answer is (3.000+0.01)times(3.000+0.01)divided by (3.000-0.01)times(3.000-0.01)answer according to my calculator says 9.0601.....ok how does that relate to the answer??am I to keep guessing what X isuntill I get the answer? or is there ...
May 9, 2010

chemistry
DR bob I got that far no probs...But dont know how to do the last bit could you expand please Thanks andy
May 9, 2010

chemistry
For the equilibrium H2(g)+CO2(g)<-->H2O(g)+CO(g) Kc=3.18 at 1106 K.If each of the four species was initially present at a concentration of 3.000M,Calculate the equilibrium concentration of the CO (g) at this temperature. Choices 0.844 3.268 3.844 3.460 2.156 Thanks ...
May 9, 2010

Chemisty 11 U
Determin the number of oxygen atmos in 1.75kg of potassium sulfate.
April 27, 2010

Chemisty 11 U
where??
April 27, 2010

Chemisty 11 U
Determin the number of oxygen atmos in 1.75kg of potassium sulfate.
April 27, 2010

Chemisty 11 U
Determin the number of oxygen atmos in 1.75kg of potassium sulfate.
April 27, 2010

Chemisty 11
thank you
April 26, 2010

Chemisty 11
Why is it important to use the correct salt-sand mix on highways during storms? Help please this is for my Chemisty Project
April 26, 2010

physics helpppp
Figure 10-35a shows a disk that can rotate about an axis at a radial distance h from the center of the disk. Figure 10-35b gives the rotational inertia I of the disk about the axis as a function of that distance h, from the center out to the edge of the disk. The scale on the ...
April 18, 2010

physics please help
Find Beta and Gamma for an electron that has a kinetic energy of 6.00 keV. gamma = KE/MoC^2 + 1 Beta = 1/gamma^2 + 1 gamma = 1.011723381 Beta = 1.9769592 I am getting gamma right but I am getting Beta wrong what I'm I doing wrong??
April 18, 2010

physics
Find Beta and Gamma for an electron that has a kinetic energy of 6.00 keV. â? gamma = KE/MoC^2 + 1 Beta = 1/gamma^2 + 1 gamma = 1.011723381 Beta = 1.9769592 I got gamma correct but my answer but im getting gamma incorrect can anyone explain what could be wrong
April 17, 2010

physics
Spaceship I, which contains students taking a physics exam, approaches Earth with a speed of 0.640 c, while spaceship II, which contains instructors proctoring the exam, moves away from Earth at 0.280 c, as in Figure P26.27. If the instructors in spaceship II stop the exam ...
April 16, 2010

physics
Spaceship I, which contains students taking a physics exam, approaches Earth with a speed of 0.640 c, while spaceship II, which contains instructors proctoring the exam, moves away from Earth at 0.280 c, as in Figure P26.27. If the instructors in spaceship II stop the exam ...
April 16, 2010

physics
Can a person, in principle, travel from Earth to the galactic center (which is about 2.3e4 lightyears distant) in a normal lifetime? Explain, using either time-dilation or length contraction arguments. If they want to make the trip in 24 y what distance would the person ...
April 15, 2010

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