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October 21, 2014

Homework Help: Science: Chemistry

Recent Homework Questions About Chemistry

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Chemistry
If 4.168 kJ of heat is added to a calorimeter containing 75.40 g of water, the temperature of the water and the calorimeter increases from 24.58°C to 35.82°C. Calculate the heat capacity of the calorimeter (in J/°C). The specific heat of water is 4.184
Wednesday, June 18, 2014 at 12:31pm

chemistry
A gas occupies 210 mL at -73°C. To have the same gas occupy 360 mL: Should the temperature be increased or decreased? What is the new temperature? A)120 K B)0.0029 K C)340 K
Wednesday, June 18, 2014 at 11:48am

physical chemistry
1 mole of element x has mass, 0.444 times the mass of 1mole of element Y. one average atom of element x has mass 2.96 times the mass of one atom of ^12c. what is the atomic wt. of Y?
Wednesday, June 18, 2014 at 7:13am

chemistry
) Calculate the amount of unreacted aqueous ethanoic acid (CH3COOH(aq)) in the sample taken for titration with aqueous potassium hydroxide(KOH(aq)). Clearly show the steps in your calculation. (1 mark) (v) Hence calculate the amount of aqueous ethanoic acid CH3COOH(aq)) in the...
Wednesday, June 18, 2014 at 7:12am

physical chemistry
the no. of atoms in 558.5g of Fe (at wt = 55.85u) is:
Wednesday, June 18, 2014 at 7:09am

physical chemistry
the atomic wt. of two elements A and B are 40 u and 80 u respectively. if x g of A contains y atoms, how many atoms are present in 2x g of B?
Wednesday, June 18, 2014 at 7:08am

physical chemistry
the isotopic abundance of C-12 and c-14 is 98% and 2% by mass respectively. what would be the no. of atoms of c-14 isotope in 12g carbon sample?
Wednesday, June 18, 2014 at 7:05am

physical chemistry
1g of hydrogen contains 6x10^23 atoms. the atomic wt. of helium is 4 u. it follows that the number of atoms in 1g of He is:
Wednesday, June 18, 2014 at 7:01am

physical chemistry
if the atomic mass of sodium is 23u the no. of moles in 46g of sodium is:
Wednesday, June 18, 2014 at 6:59am

physical chemistry
a sample of ammonium phosphate (NH4)3PO4 contains 3.18 mole of H atoms. number of mole of o atoms in the sample is:
Wednesday, June 18, 2014 at 6:58am

physical chemistry
the atmospheric pressure on mars is 0.61 kPa. what is the pressure in mm of Hg?
Wednesday, June 18, 2014 at 6:56am

physical chemistry
which one of the following pairs of gases contains the same no. of molecules:
Wednesday, June 18, 2014 at 6:52am

physical chemistry
the approximate no. of molecules of co2 present in 44g of co2 is:
Wednesday, June 18, 2014 at 6:50am

physical chemistry
indium(atomic wt.= 114.82 u ) has two naturally occuring isotopes, the predominant one from has isotopic wt. 114.9041 and abundance of 95.72%. which of the following isotopic wt. is the most likely for the other isotope?
Wednesday, June 18, 2014 at 6:46am

physical chemistry
on chemical scale, the relative mass of the isotopic mixture of x atoms (x^20,x^21,x^22) is approximately equal to:(x^20 has 99 percent abundance)
Wednesday, June 18, 2014 at 6:43am

chemistry
The activation energy, Ea, for a zeroth-order reaction, X-->products, is most readily obtained from the slope of a plot of: (choose from below) -[X] vs time -ln k vs time -rate vs time -[X]^2 vs time -ln[X] vs time -1/[X] vs time -ln k vs 1/T, where T is temperature in -ln ...
Wednesday, June 18, 2014 at 12:54am

chemistry
A reaction has a first order rate constant of (6.25x10^-5 1/s) at T=298.15K and (0.0000538 1/s) at T=338.15K. What is the value of the rate constant at T=316.15K?
Wednesday, June 18, 2014 at 12:50am

chemistry
According to the mechanism below, what is the correct expression for the rate consumption of A? In the mechanism, M is a molecule that collides with A and A* is a highly-energized for of A. Step 1: A+M <--> A*+M : rate constants k1 and k-1 Step 2: A* <--> C : rate ...
Wednesday, June 18, 2014 at 12:48am

chemistry
The decomposition reaction, x-->products, is second-order with rate constant k=0.0183 L/(s)(mol). How long will it take for the decomposition to be 95% complete, if the intitial concentration of X is 1.25mol/L? Thanks
Wednesday, June 18, 2014 at 12:44am

organic chemistry
1. Arrange the following in order of decreasing reactivity toward nitration. Fully explain please I could use some help!! A. acentanilide, b. bromobenzene, C. acetophenone, D. toluene 2. Explain why p-nitrophenol is a stronger acid than phenol itself? Would p-methoxyphenol be ...
Tuesday, June 17, 2014 at 10:32pm

Chemistry
1. Nitric acid is produced via the following equation: 3 NO2 + H2O = 2HNO3 + NO. How many grams of NO2 are required to produce 7.5 grams of HNO3?
Tuesday, June 17, 2014 at 10:00pm

Chemistry - Electroplating - URGENT
"To save on production costs, most automobile bumpers are never coated with more than 200 g of chromium. Determine how much time a standard bumper should be immersed in a chromium vat." This is what I have so far- 96,485 coulombs are required to plate 1 Cr; 52/6 = 8....
Tuesday, June 17, 2014 at 8:40pm

chemistry
"To save on production costs, most automobile bumpers are never coated with more than 200 g of chromium. Determine how much time a standard bumper should be immersed in a chromium vat." This is what I have so far- 96,485 coulombs are required to plate 1 Cr; 52/6 = 8....
Tuesday, June 17, 2014 at 8:38pm

CHemistry
What is the concentration of Sulfate ion in a 0.5 M solution of Al2(SO4)3?
Tuesday, June 17, 2014 at 6:59pm

Organic Chemistry
These questions are somewhat difficult. I believe I am on the right track, but I want to make sure. 1. List these compounds in order of decreasing reactivity towards nitration. Explain your answer. a) acetanilide b) bromobenzene c) toluene d) acetophenone 2. a) Which is the ...
Tuesday, June 17, 2014 at 6:10pm

chemistry
find (i) the total no. of neutrons and (ii) the total mass of neutrons in 7mg o^14C. (assume that the mass of a neutron = mass of a hydrogen atom)
Tuesday, June 17, 2014 at 6:32am

chemistry
the weight of one atom of uranium is 238 amu. its actual wt. is ......g
Tuesday, June 17, 2014 at 6:30am

chemistry
how much time(in years) would it take to distribute one avogadro number of wheat grains if 10^10 grains are distributed each second?
Tuesday, June 17, 2014 at 6:28am

chemistry
the density of liquid mercury is 13.6 g/cm^3. how many moles of mercury are there in 1 litre of the metal?
Tuesday, June 17, 2014 at 6:26am

chemistry
average atomic mass of magnesium is 24.31 amu. this magnesium is composed of 79 mole % of ^24 Mg and remaining 21mole % of ^25 Mg. calculate mole % of ^26Mg.
Tuesday, June 17, 2014 at 6:25am

chemistry
calculate the number of malecules in a drop of water weighting 0.09 g
Tuesday, June 17, 2014 at 6:23am

chemistry
calculate the no. of molecules in 16g of methane is:
Tuesday, June 17, 2014 at 6:20am

chemistry
a sample of ethane has the same mass as 10million mulecules of methane. how many moles of CO2 are left?
Tuesday, June 17, 2014 at 6:19am

chemistry
the no. of neutrons in 5g of D2O(Dis 2/1 H) are:
Tuesday, June 17, 2014 at 6:14am

chemistry
calculate the wt. of 6.022x 10^23 formula units of CaCO3
Tuesday, June 17, 2014 at 6:12am

chemistry
from 200 mg of CO2, 10^21 molecules are removed. how many moles of CO2 are left?
Tuesday, June 17, 2014 at 6:09am

chemistry
if from 10 moles NH3 and 5moles of H2SO4 all hte H-atoms are removed in order to from H2 gas, then find the no. of H2 molecules formed.
Tuesday, June 17, 2014 at 6:06am

chemistry
if from 3moles MgSO4.7H2O all the 'o' atoms are taken out and converted into ozone, find the number of O3 molecules formed.
Tuesday, June 17, 2014 at 6:04am

chemistry
if the components of air are N2-78% ;O2-21%; Ar-0.9% and Co2-0.1% by volume (or mole) what would be the molecular weight of air?
Tuesday, June 17, 2014 at 6:01am

Chemistry
if 50 ml of a solution of ph 3 is mixed with 50 ml of a solution of 5, explain why the resulting ph is still about 3 and not 4?
Tuesday, June 17, 2014 at 5:01am

chemistry
Calculate the volume of nitrogen gas that will be produced in the air bag of a car when 88,8g of sodium azide is thermally decomposed at 22 C to give the bag a pressure of 1,10 atm
Tuesday, June 17, 2014 at 12:08am

Science (Chemistry)
4. A Beer’s Law plot was prepared for the reaction A(aq) + B(aq) AB(aq), plotting absorption over AB(aq) concentration. The linear equation for this plot was y = 78.3x. A solution was prepared by mixing 10.0mL of 0.100M A with 5.00mL of 0.100M B and adding enough ...
Monday, June 16, 2014 at 7:58pm

Chemistry
Determine the mass of carbon dioxide that will be formed when 131.0 g of propane (C3H8) is reacted with 32 g of oxygen (O2) C3H8 + 5O2 --> 3CO2 + 4H2O I got O2 as my limiting reagent. Then I used the mol of that which is 1 mol to find the mol of CO2 which I got as 0.6 mol. ...
Monday, June 16, 2014 at 7:31pm

CHEMISTRY
COPPER
Monday, June 16, 2014 at 1:50pm

Chemistry
Ramesh took two beakers A and B containing hot water and cold water respectively . In each beaker he dropped a crystal of copper sulphate . He kept it undisturbed. After some time what did he observe ? Why ?
Monday, June 16, 2014 at 1:42pm

chemistry
If i have 12 grams of potassium chlorate dissolved in 100g of water at 65 celsius how much would i need to make the solution saturated
Monday, June 16, 2014 at 11:38am

chemistry
Cobalt(2) chloride is commonly obtained from chemical supply houses as a hydrate with the formula COCL2*6H2O an analysis showed that 25.0 g of this hydrate contains 11.3 g of water what is the percent water by weight in this hydrate?'
Monday, June 16, 2014 at 8:31am

Chemistry
What volume of 0.109 M nitric acid is required to neutralise 2.50g barium hydroxide?
Monday, June 16, 2014 at 3:49am

chemistry
What is the chemical formula of ketohexose?
Sunday, June 15, 2014 at 8:21pm

analytical chemistry
Determine the concentration of iron in an aqueous solution containing 0.2810 grams of Fe(NH4)2(SO4)2 per liter of solution. Express the concentration in mg/dl.
Sunday, June 15, 2014 at 6:54pm

chemistry
calculate the percentage by mass of oxygen in trioxonitrate(v) acid
Sunday, June 15, 2014 at 5:27pm

Chemistry
In aqueous solution, hydrochloric acid, HCl, and sodium carbonate, Na2CO3 react to produce gaseous carbon dioxide, CO2, water, H2O and sodium chloride, NaCl. A 10.0 g impure sample of Na2CO3 is dissolved completely in water; then treated with 3.00 mol L−1 HCl to evolve ...
Sunday, June 15, 2014 at 3:36pm

chemistry
calculate the percentage by mass of ozygen in trioxnitrate5 acid H-1, N-14, O-16
Sunday, June 15, 2014 at 1:03pm

chemistry
To 50 mL of this buffer, 10.0 mL 0.76 M soium hydroxide was added, what is the pH of the resulting solution after equilibrium has been re-established
Sunday, June 15, 2014 at 6:47am

Chemistry
Benzene sulfonic acid, C6H5SO3H, is a strong acid and will neutralise sodium hydroxide solution (a 1:1 molar ratio). Benzene sulfonic acid crystals (y grams) were weighed into a titration flask and titrated against sodium hydroxide solution (1.0 M) and needed a volume of 26.2 ...
Sunday, June 15, 2014 at 5:07am

Chemistry
how many millimeter should be taken out to prepare 0.5 normal HCL solution of 200 ml. density=1.18, purity 37% please response soon
Sunday, June 15, 2014 at 1:50am

chemistry
two metals (copper and aluminum ) were placed into two separate beakers which both contained 0.5M CaCl2. Give a detailed description as to what might observed in each beaker as time progressed
Saturday, June 14, 2014 at 11:53am

CHEMISTRY
WHEN CAP OF SOFT DRINK IS REMOVED THEN ITS MASS FIRST INCREASES AND THEN DECREASES WHY?
Friday, June 13, 2014 at 11:17am

physical science(chemistry change)
Experiment of tiratic oxilic acid wih mass 4,5g and volume of 25ml,nd concentration of 0,05mol.dm.3 against volume of 14ml and 1,79mol.dm3 sodium hydoxide to determine the concentration of sodium hydroxide,,show all the working,aim,results,observation of result,discussion
Thursday, June 12, 2014 at 12:05pm

physical science(chemistry change)
Experiment of tiratic oxilic acid wih mass 4,5g and volume of 25ml,nd concentration of 0,05mol.dm.3 against volume of 14ml and 1,79mol.dm3 sodium hydoxide to determine the concentration of sodium hydroxide,,
Thursday, June 12, 2014 at 12:04pm

science-chemistry
Calculate the number of moles of solute present in 450. g of an aqueous NaCl solution that is 0.565 % NaCl by weight
Thursday, June 12, 2014 at 11:11am

Chemistry
If you need to make a solution of 1.0L at 2.5M citric acid and you only have 45mL of 5.0M citric acid, do you have enough for your experiment? If a mathematical procedure is involved, please explain to me; I really want to grasp this chemistry concept.
Wednesday, June 11, 2014 at 8:18pm

CHEMISTRY
WHEN CAP OF SOFT DRINK IS REMOVED THEN ITS MASS FIRST INCREASES AND THEN DECREASES
Wednesday, June 11, 2014 at 2:43pm

Chemistry
what is the mass of nh4cl that must dissolve in 100. grams of h2o to produce a saturated solution at 70 degrees celsius
Wednesday, June 11, 2014 at 11:32am

chemistry
what's the discussion for determine BaCl2.2H2O in lab report
Wednesday, June 11, 2014 at 11:27am

chemistry
if an excess of nitrogen is reacted with 3.41 g of hydrogen, how many grams of ammonia can be produced?
Wednesday, June 11, 2014 at 9:21am

chemistry
What is the Ka of a weak acid (HA) that produces a pH of 3.45 with 0.1M? 2.54E-3 3.45E-3 1.27E-6 3.56E-3 5.48E-4
Tuesday, June 10, 2014 at 9:22pm

chemistry
Consider the equation 2kclo3(s) -> 2kcl(s)-1302(g). 3.00-g sample kclo2 is decomposed and the oxygen at 24.0 and 0.982 its either, 911, 304, or 608
Tuesday, June 10, 2014 at 5:45pm

chemistry
A sample of gas (1.9 mol) is in a flask at 21 °C and 697 mm Hg. The flask is opened and more gas is added to the flask. The new pressure is 795 mm Hg and the temperature is now 26 °C. There are now __________ mol of gas in the flask.
Tuesday, June 10, 2014 at 12:49pm

Chemistry
what is the pH solution in which 15 mL of 0.10 M NaOH has been added to 25 mL of 0.10 M HCl
Tuesday, June 10, 2014 at 10:18am

Chemistry
Consider the following equilibrium. 2 SO2 (g) + O2 (g) 2 SO3 (g) The equilibrium cannot be established when __________ is/are placed in a 1.0-L container.
Monday, June 9, 2014 at 9:07pm

CHEMISTRY
How much 0.200 M KOH is required to completely neutralize 25.0 mL of 0.150 M HClO4?
Monday, June 9, 2014 at 7:49pm

CHEMISTRY
How many liters of softened water, containing a sodium concentration of 0.050% sodium by mass, have to be consumed to exceed the FDA recommendation? (Assume a density of 1.0 g/mL for water.)
Monday, June 9, 2014 at 7:34pm

Chemistry
A butane lighter had a mass of 24.643 grams before lighting and a mass of 24.592 grams after. How many mL of CO2 were produced? Assume STP.
Monday, June 9, 2014 at 6:01pm

chemistry 2
What is the value for ∆Soreaction for the following reaction, given the standard entropy values? 2 Al (s) + 3Cl2(g) 2AlCl3(s) a.-503 J/K b.+503 J/K c.-140 J/K d.+140 J/K
Monday, June 9, 2014 at 4:57pm

Chemistry
5.2 grams of magnesium metal are place in 400.0 mL of 1.0 M hydrochloric acid. The balanced equation for the reaction is: Mg + 2HCl = MgCl2 + H2. How many moles of H2 gas were produced?
Monday, June 9, 2014 at 3:37pm

Chemistry
I need help on these three questions. For all three of them you're supposed to write a balanced equation for each neutralization. Then, to find the concentrations of the unknown solutions if the following reactions are found to reach equivalence by titration. The three ...
Monday, June 9, 2014 at 2:03pm

Chemistry
How would you prepare pure dry crystals of pottasium trioxonitrate (v) ?.
Monday, June 9, 2014 at 1:52am

Chemistry
If 3.50 mol of A is mixed with 0.750 mol of B and the final pressure of the mixture is 3.25 atm, what are the partial pressures of A and B
Sunday, June 8, 2014 at 11:09pm

Chemistry
27. Excess exposure to nuclear radiation can cause harm. All of the following statements about radiation are true EXCEPT A. Radiation can damage living tissue because of the high energy associated with the radiation. B. Radiation can damage biological molecules by knocking an ...
Sunday, June 8, 2014 at 9:55pm

Chemistry
what volume (mL) of 0.0962M NaOH is required to neutralize 10.0mL of 0.128M H2SO4? I got 26.6mL
Sunday, June 8, 2014 at 9:28pm

Chemistry
23. In a chemical reaction, dynamic equilibrium occurs when the rate of the forward reaction becomes precisely equal to the rate of the reverse reaction. All of the following statements are true EXCEPT A. A dynamic equilibrium occurs when the reaction is more than 50 percent ...
Sunday, June 8, 2014 at 5:24pm

Chemistry
I posted this last night, A 0.500L vessel initially contains 0.0125 mol of H2S2 . Find the equilibrium concentrations of H2 and S2. Kc = 1.67 x 10^-7 2 H2S <--> 2 H2 + S2 I have come up with this equation so far, but I am lost now because I don’t even know if this ...
Sunday, June 8, 2014 at 11:22am

chemistry
If the pH of an aqueous solution is 5, what is the OH− concentration?
Sunday, June 8, 2014 at 11:16am

chemistry
What is the pH of a water solution at 25◦C in which the hydroxide ion concentration is 9.8 × 10−6 mol/L?
Sunday, June 8, 2014 at 11:15am

chemistry
Calculate the [H+] for a solution with [OH−] = −80 M. 1x10*-14/-80=-log(answer) How would I do this since I can not take the negative log of the previous anwser
Sunday, June 8, 2014 at 11:12am

chemistry
Urea (CO(NH2)2) can react with water to form CONH2NH+ 3 and a hydroxide ion. Which statement is true for this reaction?
Sunday, June 8, 2014 at 11:05am

chemistry
Calculate the pH of an aqueous solution of 11.5 mg of KOH dissolved in 56 mL of solution.
Sunday, June 8, 2014 at 11:00am

Chemistry/physics
The KE of a hydrogen atom's electron is 12.65 eV. Calculate the velocity of the electron? Known: KE=mv^2
Sunday, June 8, 2014 at 10:20am

chemistry
46,318.97
Sunday, June 8, 2014 at 5:54am

chemistry
calculate the mass of Cuso4.5H2O required to prepare 500 cm3 of a 0.400 m/dm-3 solution
Sunday, June 8, 2014 at 5:31am

Science - chemistry
The osmotic pressure of a solution of MgCl2 is 5.43 atm at 25 oC. How much of the salt is dissolved in 250.0 ml of water?
Sunday, June 8, 2014 at 3:14am

Science - chemistry
The SO2 present in air is mainly responsible for the phenomenon of acid rain. The concentration of SO2 can be determined by titration against a permanganate solution of known concentration as follows: SO2 + MnO4^-1 -> SO4^-2 + Mn2+ (unbalanced) Balance the equation showing ...
Sunday, June 8, 2014 at 3:03am

chemistry
i need help solving this Benzoic acid is a weak, monoprotic acid (Ka = 6.3 × 10−5). Calculate the pH and the percent dissociation of each of the following solutions of benzoic acid. Then use Le Châtelier’s principle to explain the trend in percent ...
Saturday, June 7, 2014 at 11:42pm

Chemistry
How many grams of pure H2SO4 can be obtained from 250 grams of iron ore if the ore is 82% FeS2? The reactions involved are given below: 4FeS2 + 11 O2 --> 2 Fe2O3 + 8 SO2 (95% efficient) 2SO2 + O2 --> 2SO3 (90% efficient) SO3 + H2O --> H2SO4 (90% efficient)
Saturday, June 7, 2014 at 10:29pm

Chemistry
A 0.500L vessel initially contains 0.0125 mol of H2S2 . Find the equilibrium concentrations of H2 and S2. Kc = 1.67 x 10^-7 2 H2S <--> 2 H2 + S2
Saturday, June 7, 2014 at 9:49pm

Chemistry
how would you do this question when i did it i did -log(1.0) but that is just 0 so what it the procedure to do this question Calculate the pH of a 1.0 mol/L aqueous solution of sodium benzoate. Note: Only the benzoate ion affects the pH of the solution.
Saturday, June 7, 2014 at 8:18pm

chemistry
How would you do this question: A student dissolved 5.0 g of vitamin C in 250 mL of water. The molar mass of ascorbic acid is 176 g/mol, and its Ka is 8.0 × 10−5. Calculate the pH of the solution. Note: Abbreviate the formula of ascorbic acid to HAsc.
Saturday, June 7, 2014 at 7:56pm

Chemistry
Which formula represents an organic acid? HCOOCH3 CH3CH2OH CH3COCH3 HCOOH Can you please help me
Saturday, June 7, 2014 at 4:18pm

chemistry
How are cis trans isomers used for night vision?
Saturday, June 7, 2014 at 4:08pm

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