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Posts by chem

Total # Posts: 138

sciaece
titration of sodium hydroxide with tetraoxosulphate4 acid.

Chemistry
If we were to fill a bottle with boiling hot water than place it in a bucket filled with cold water what would happen to the bottle and why? i know the bottle would get crushed inwards but whats the science behind this can someone explain?

Chemistry
What is the molarity of the final solution if 2.00mL of the 5.00 M stock solution is diluted to 10.00mL to make solution A? Solution A then undergoes a second dilution by taking 3.00mL solution A and diluting it to 25mL.

chemistry
When performing an extraction, is it better to have a higher or lower K (distribution coeffictient/ partition coefficient) value? Explain.

chemistry
im not to sure what phen and en are short for. but im thinking the answers maybe d) if zinc is bonded to 2 (NH3) and if en means the rest of atoms its bonded to are the same.??

chemistry
Which one of the following complex ions has an optical isomer? a. [Zn(phen)2]2+ b. [Cu(CN)4]2– c. [Co(H2O)4en]2+ d. [Zn(NH3)2en]2+ e. [Ni(en)3]2+ how would i go about finding this answer? i don't need the answer give would prefer steps. thanks

chemistry
Nylon 88 is made from the monomers H2N(CH2)8NH2  and  HOOC(CH2)6COOH.  So, would you characterize nylon 88 as rather an addition or a condensation polymer? Please explain your answer

Chemistry
A hot air balloon is filled with hot air and the hot air forces the volume of the balloon to expand until the density of the gas in the balloon is less than the density of the outside air. The volume must be 20% larger than the balloon would be at STP in order for the balloon ...

chemistry
How much pure calcium carbonate (100.09 g/mol) is required to produce 40.0 mL carbon dioxide gas according to the reaction used in this experiment? Your unknown will contain between 25-100% calcium carbonate. Answer to 3 significant figures. Do not include the unit, g. Hint...

Chemistry
so, I guess the question is "m of AgCl produced"???

chemistry
[base] > [acid] so your pH should be larger than pka. check DrBob's answer :)

Chemistry
q = 3.4 x 334 J/g

chemistry
0.947 moles of NaC2H3O2 dissolved in 100 mL solution

chemistry ap
Assume that 29.7 g of Al react with HCl according to the equation Al(s) + HCl(aq) −→ AlCl3(aq) + H2(g) at STP. How many moles of Al react? Remember to balance the equation first. Answer in units of mol. How many moles of H2 are produced? Answer in units of mol. How...

chemistry ap
20.0 L of methane (CH4) undergoes complete combustion at 0.961 atm and 20◦C. How much CO2 is formed? Answer in units of L.

chemistry ap
Nitric acid can be produced by the reaction of gaseous nitrogen dioxide with water. 3 NO2(g) + H2O(ℓ) −→ 2 HNO3(ℓ) + NO(g) If 734 L of NO2 gas react with water, what volume of NO gas will be produced? Assume the gases are measured under the same ...

chemistry ap
Assuming all volume measurements are made at the same temperature and pressure, what volume of hydrogen gas is needed to react completely with 3.25 L of oxygen gas to produce water vapor? Answer in units of L.

chemistry ap
Zinc reacts with 18.0 mL of 6.00 M cold, aqueous sulfuric acid through single replacement. a. How much zinc sulfate is produced? Answer in units of g

chemistry
An aqueous solution contains 0.445 M ethylamine (C2H5NH2). How many mL of 0.226 M hydrochloric acid would have to be added to 150 mL of this solution in order to prepare a buffer with a pH of 10.200

Chemistry
Use your balanced equation to calculate the volume of 0.12 M Na3PO4 to stoichiometrically react with the 3.0 mL of Co (NO3)2. Show your work.

Chemistry
Where Co(NO3)_2 is the limiting reagent the mmoles of the precipitate will be related to the mmoles of Co(NO3)_2 originally present by the balanced stoich. and the filtrate will be colorless? And if Na_3PO_4 is the limiting reagent the filtrate will be red/pink? This is my ...

Chemistry
Procedure 0) The sodium phosphate, Na3PO4 solution has NPFA ratings of 1 (out of 4) for health, 0 for fire, and 0 for reactivity. Cobalt (II) nitrate has 2 for health, 0 fire, and 0 for reactivity. 1) Carefully label (1-­‐6) and weigh 6 small test tubes. 2) You will ...

Chemistry
Procedure 0) The sodium phosphate, Na3PO4 solution has NPFA ratings of 1 (out of 4) for health, 0 for fire, and 0 for reactivity. Cobalt (II) nitrate has 2 for health, 0 fire, and 0 for reactivity. 1) Carefully label (1-­‐6) and weigh 6 small test tubes. 2) You will ...

Chemistry
Discuss how your supernatant color in the 6 different test tubes supports your calculated result in #2. For example, if you used less than the volume of sodium phosphate calculated in #2, what would be the limiting reactant and does the observed supernatant color support this.

chemistry
10.4 grams

Ochem
What volume of eugenol will be present in 30 mL of distillate? The essential oil found in cloves, eugenol, can be isolated by steam distillation because it is insoluble in water and has a measurable vapor pressure at 100 °C even though it has a much higher boiling point ...

Chemistry
carbon dioxide dissolves in water to form carbonic acid. Estimate the thermodynamic equilibrium constanst (K) for this reaction (delta Gf values: H2CO3= - 616.1, H2O= - 237.1, CO2= - 394.4) . Carbonic acid then ionizes in water (Ka1= 4.5 x 10^-7). Ignoring Ka2, estimate (K) ...

CHEM
A particular reactant decomposes with a half-life of 139 seconds when its initial concentration is 0.342 M. The same reactant decomposes with a half-life of 237 seconds when its initial concentration is 0.201. What is the value and unit for this rate constant?

Chem
4.30 grams of NH4Cl is added to 14.5 grams of water. Calculate the molality of the solution

Chemistry
When weighing liquid ethanol, why do you have to place water in the beaker prior to adding the ethanol to that same beaker?

chemistry
Which of the following statements describes why ion exchange of 99% SiO2 - 1% B2O3 in a salt bath of molten postassium chloride (KCl) is not an effective way to increase the surface strength of the glass sample? The ion exchange works correctly, however both air-cooling and ...

science
C6H12 = 6x12 + 6x1 = 78. The equation indicates that 2x78 = 156g benzene will produce 6542kJ. Using proportions you can then calculate that x/6542kJ = 8.1g / 156g x = 339.7kJ = 339700J. heat = mass x ΔT x 4.18J/g° ΔT = 339700J / (5691g x 4.18J/g°) = 14.3°...

chemistry
11.76

Chemistry
What is the pH of a 0.20 M HF solution that is 5.8% ionized at 25 Celsius ? A.4.45 b.0.70 C.1.93 D.1.23 E.1.40

Chemistry
What are answers of a) and b) ??

Chemistry
Image one (d) Image two (a) I hope this helps. :)

Stela
CCl4 ClO4− ClF4− SiCl4 SO42− Which molecule or ion does not have a tetrahedral molecular geometry?

Chemistry
Btw, I did it the way you said and I still come up with the same conversion of 29.8 * (760/1)= 22648

Chemistry
Sorry, my post repeated by accident when i refresh my page

Chemistry
Using the "octet rule" write the Lewis formulas for NF3 and NO3-.

Chemistry
How do you draw a lewis dot structure of s3o

chem
How to find the %(W/V) of 134mL of a 0.610 M solution of Mg(OH)2

CHEMISTRY
100.016 or 1.00 x 10^2 kj/mol

Chemistry
Explain the function of the aluminum wire and the mercury II chloride when testing for tin? when testing for antimony, what reagent prevents tin from reacting with the H2S to form SnS2? What reagent is used to identify copper and explain its function.

chemistry
How much energy (in kilojoules) is released when 21.0 of ethanol vapor at 94.5 is cooled to -19.0?

organic chem
cadaverine is AKA pentane-1,5-diamine

Chemistry
In the laboratory exercise "Preperation and Properties of Polymers", polyvinyl alcohol is dissolved in water and then reacted with borax (Na2B4O7·10H2O) in water. Which of the following are expected results of this reaction? True or False? 1. Polyvinyl alcohol...

Organic Chemistry
Suggest structures for C10H14O; C10H16; C10H18; C10H16O3; C10H16O2 ; C12H22O2 in the following reaction schema: The UV/Visible spectrum for C10H14O exhibits a at 244 nm C10H16 + hot KMnO4 + H2SO4 → C10H16O3 C10H16O3 + Zn(Hg)/conc HCl → C10H18O2 C10H18O2 + CH3CH2OH...

Organic Chemistry
The UV/Visible spectrum for C10H14O exhibits a at 244 nm C10H16 + hot KMnO4 + H2SO4 → C10H16O3 C10H16O3 + Zn(Hg)/conc HCl → C10H18O2 C10H18O2 + CH3CH2OH + H3O+ → C10H22O2

chem
Sarah, 4.70 is what you get when you do the -log (Ka)

chem
Thank you

chem
Calculate the volume of 0.200 M acetic acid and the volume of 0.100 M sodium acetate required to make 200.0 mL of a buffer solution with pH = 5.00. The Ka for acetic acid at 298 K is 2.00 x 10-5.

chemistry
I don't understand how you do (b), I got 173kJ for (a) and I understand Hess's law for (c), but (b) I really don't understand (b)

Chemistry
True/False 1. Diatomic molecules contain two atoms?T 2. Electrons travel in pairs? T 3. The energies needed to break chemical bonds can be measured T 4. Bonding involves all the electrons in an atom T 5. Lewis structures are used to describe bonding? F 6. More than one pair of...

science
An excess of aluminum metal is added to 200.0 mL of 0.025 M solution of CuCl2, reducing the Cu+2 ions to metallic Cu. If the temperature of the solution increases from 25.0 to 27.5 degrees celsius, what is the enthalpy of this reaction per mole of Cu formed? (Specific heat of ...

chemistry equilibriums
At a certain temperature, 2.00 moles of phosphorus(V) chloride, PCl5, was placed in a 1.0 L vessel and permitted to react as shown: PCl5 (g) <-> PCl3 (g) + Cl2(g) At equilibrium, the container held 0.40 PCl5. What is the numerical value of Kc for the system as written? A...

chemistry
C3H7OH right?

chemistry
On complete oxidation, one mole of an organic compound produced four moles of water. Which one of the following substances could it be? CH4 C2H6 C3H7OH C4H10 So I added O2 to each of these compounds, but I must be doing something wrong because I can't get 4 moles of water...

Chemistry
ln166.44-lnx=0.64766*1.73 -lnx=1.120-ln166.44 lnx=3.9942 x=E^3.9942 =54.27 166.54-54.27=112g

Chemistry
Sucrose hydrolyzes into glucose and fructose. The hydrolysis is a first order reaction. the half life for the hydrolysis of sucrose is 64.2min at 25C. How many grams fo sucrose in 1.25L of a 0.389M solution are hydrolyzed in 1.73hrs? I started off by finding k the constant t1/...

Chemistry
Thank you for you help

chem: study of kinetics
he gave us an example of what the slope might be in class and it was -1.3x10^2 but my slop is completely different, was i supposed to do calculations? or just get the one from excel? what do i put in the 2 blanks?

chem: study of kinetics
im supposed to find the slope= -EA/R = triangle y/triangle x = (y2-y1) ________/(x2-x1)____________ how do i do this? is it the same as the slope that excel gave me? i have information from 3 different groups, and i have 3 x's and 3 y's, how do i solve this? the ...

chem lab
hi im doing a post lab sheet for chem class. and im having a little trouble. i have: temperature 12.6 C -> 285.6 K Time 816 sec but im supposed to find 1/T(K) it looks like my classmate did this: 12.6 x 285.6 = 3598.56 however they gave me the response to group 2 also: and ...

jessie
if im missing any information, please let me know. just simple steps would be really helpful!

jessie
hi im doing a post lab sheet for chem class. and im having a little trouble. we did an experiment where we put a mixture into a bath and checked to see how long a color would leave from the mixture. i have temperature 12.6 C -> 285.6 K Time 816 sec but im supposed to find 1...

Enthalpy of Formation
I got the answer to be 95.4 kj/mol I reversed the 1st equation to get an overall 187.6 kj = h1 then I just added that to H2 and I got the answer. But I still don't really understand the processes. If someone could explain that to me I would truly appreciate it.

Enthalpy of Formation
N2H4(g) + H2(g)--> 2 NH3(g) H1 = –1876kJ 3 H2(g) + N2(g)--> 2 NH3(g) H2 = –922 kJ The H.f for the formation of hydrazine: 2 H2(g) + N2(g)--> N2H4(g) will be______kj/mol I am very confused here. I thought I would just add H1 and H2 and divide by the molar ...

Unit Cells
I got it thank you! The A^3 was suppose to stand for ångström cubed...

Unit Cells
Copper has a unit cell volume of (47.453 A^3) and a face centered unit cell. How would I go about finding the volume of atoms within the unit cell? Would you use Avogadro's # somehow?

gen chem
that works! thank you so much!!

gen chem
yes, I figured that one out. Thanks so much for the help!

gen chem
2NO <-> N2 O2 initial .116 0 0 change -x +x +x equil .116-x x x

gen chem
yes I did, but im still not getting the right answer. I got .1136 which is not the correct answer.

gen chem
At 2273K, equilibrium constant for the reaction 2NO(g)<->N2(g)+O2(g) Kc=2.4x10^3 What would be equilibrim concentration of N2, if initial concentration of NO was 0.1160M?

gen chem
yes, it wants an actual value

gen chem
what would Qc be if the pressure of the container decreased by a factor of 2.417 for the following reaction? 4Hcl(g)+O2(g)<-->2Cl2(g)+2H2O(g) Kc=13.298 @ 753K

gen hem
what is the free energy change in kJ for the reaction below? 2NO3-(aq)+8H+(aq)+3Hg(l) <-->2NO(g)+4H2O(l)+3Hg2+(aq) E0=0.106V

gen chem
i tried that, apparently its not the right answer either =/.

gen chem
with n=10, im getting an answer of 0 when I do e^(k) i got lnK= (10)(96485)(-1.133)/(8.314)(298) lnK=-441.228 e^(-441.228)=0

gen chem
what is "n" and thank you so much for all the help!

gen chem
E cell is not given, just the E0 cell which is -1.133V

gen chem
what is the pK (=-logK)at 25C for the reaction below? Cl2(g)+6H2O(l)+5Cu2+(aq)<-->2ClO3-(aq)+12H+(aq)+5Cu(s) E0=-1.133V

gen chem
if the voltage of the cell is 2.0898V at 25C when [Mg2+] = 0.1945M and the pressure of H2 = 1.00atm, what is the pH? E0=2.3700V Mg(s)+2H+(aq)<--> Mg2+(aq)+ H2(g)

gen chem
what must be the current in amperes to plate out 7.437g of Al from am aqueous solution of Al3+ in 5.4x10^2 minutes?

General Chemistry
How much energy in kJ is realeased to form one mole of Cd 116(isotope) from protons and neutrons if the atom has a mass of 115.90476amu.

Molarity/molality
Ohhhhh That makes so much more sense. I didn't fully understand what the problem was asking. Thank you so very much =)

Molarity/molality
In regards to your latest post, I meant the very first step, not the step you did to check the answer. I'm assuming the first line is a typo?

Molarity/molality
And I'm a little unsure as to why after you find the mass of the solution 1059.269 you find how many g of H20 are in 1000 g of that soln. Why can't we just use the 1058.269 g? Was it to get the perfect 1000g (1kg) or was that unnecessary?

Molarity/molality
This makes more sense, but your first step is a little confusing. when I do 26.70 x 18.015 g H2O/mol I get 481.005 but when I do: 3.29 m x 18.015 g H2O/mol then I get your ans: 50.269 g H20

Molarity/molality
Thank you! I got the correct answer.

Molarity/molality
I found another post on this site, which explains a similar problem. :)

Molarity/molality
A 3.29 m solution of the solute H2O dissolved in the solvent acetone is available. Calculate the mass ( kg ) of the solution that must be taken to obtain 26.70 mol of H2O. m= molality I have no idea how to approach this problem, I'm not interesting in getting the answer, I...

CHemiStry!
its just the 2nd and 4th one

CHemiStry!
Select all ionic compounds in which the number of anions present is two. carbon dioxide X manganese(II) hydroxide mercury(II) carbonate X mercury(II) phosphate ammonia sulfur dioxide Hello, I know manganese(II) hydroxide mercury(II) phosphate both have two anions, however I am...

Chemistry
what would the freezing point be for a solution of 0.87M aqueous ammonia? The density of this solution is 0.992g/cm3

Hydrogen Bonding
The longer the hydrogen bond, do the Intermolecular Forces increase or decrease. So if molecule A has a H-bond with a length of 1.7 A and molecule B has a H-bond length of 1.8 A would molecule A or molecule B have a stronger IMF? It would seem that the longer the bond length ...

college Chemistry
If [K+] inside a cell is 25 times greater than a [K+] outside the cell, what is the difference in potential between the two sides of the cell wall? (this is a "concentration cell" style of problem)

CheMistry
Okay thank you that makes a lot more sense!

CheMistry
A stock solution was prepared by dissolving exactly 0.4000 g of pure ASA (180.16 g/mol) in 10.00 mL of NaOH and heating the solution to a gentle boil. After cooling to room temperature, the solution was poured into a 250-mL volumetric flask and diluted to the mark with DI ...

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