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July 6, 2015

Homework Help: Science: Chemistry

Recent Homework Questions About Chemistry

Chemistry
A very old and tired , grey haired AP Chem instructor wanted to determine the Ka of an unlabelled monoprotic acid in his stockroom. He dissolved an unknown amount of acid in an unknown amount of water and proceeded to titrate the sample with a solution of NaOH of unknown ...
Sunday, February 24, 2013 by Summer

Chemistry
A very old and tired , grey haired AP Chem instructor wanted to determine the Ka of an unlabelled monoprotic acid in his stockroom. He dissolved an unknown amount of acid in an unknown amount of water and proceeded to titrate the sample with a solution of NaOH of unknown ...
Sunday, February 24, 2013 by Kat

Chemistry
A 0.010M solution of base B is 15% dissociated. Calculate the Kb for base B.
Sunday, February 24, 2013 by James

chemistry
2 HI(g) H2(g) + I2(g) The reaction above has an initial concentration of 2.00 M HI. (No other species are initially present.) If 22.4% of the HI has reacted when equilibrium is established, calculate Kc for the reaction.
Sunday, February 24, 2013 by shabaka

Quantum chemistry
For the simple harmonic oscillator determine: b. [Tˆ,Vˆ ]
Sunday, February 24, 2013 by Adam

Chemistry
Mg + 2HCl -> MgCl2 + H2 Over an interval of 1.00s, the mass of Mg changes by -0.011g What is the corresponding rate of consumption of HCl (in mol/s)? I got 9.0E-4 mol/s and that's the right answer. But I'm having problems with the next question. Calculate the ...
Sunday, February 24, 2013 by a Canadian

chemistry (Pls Bob check for me)
A 1.2g mixture of na2c03 and k2c03 was dissolved in water to form 100cm3 of s solution, 20cm3 of this solution required 40cm3 of 0.1N hcl for neutralization. Calculate the wieght of na2c03 and k2c03 in the mixture The answer 0.4G My own calculation: na2c03 weight = 106g/2 = ...
Sunday, February 24, 2013 by Fai

Chemistry
I need help in solving this problem: A certain substance has a heat of vaporization of 42.46 kJ/mol. At what Kelvin temperature will the vapor pressure be 5.00 times higher than it was at 291 K? I know that I have to use the Clausius-Clapeyron equation, but what would I be ...
Sunday, February 24, 2013 by Confused

Chemistry
4Fe + 3O2 = 2Fe2O3 So in math book it say " You can interpret this equation in terms of representative particles by saying that four atoms of iron react with three molecules of oxygen to produce two formula unit of iron(iii) oxide" Why it say that there are 4 atoms ...
Sunday, February 24, 2013 by Shadow

AP Chemistry
A very old and tired , grey haired AP Chem instructor wanted to determine the Ka of an unlabelled monoprotic acid in his stockroom. He dissolved an unknown amount of acid in an unknown amount of water and proceeded to titrate the sample with a solution of NaOH of unknown ...
Sunday, February 24, 2013 by Sarah

chemistry
Consider a mixture of the two solids BaCl2 * 2H2O (FW=244.26 g/mol) and KCl (FW=74.551 g/mol). When the mixture is heated to 160 C for 1 hour, the water of crystallization is driven off: BaCl2 * 2 H2O (s)  BaCl2(s) + 2 H2O(g) A sample originally weighing 1.7839 g is ...
Sunday, February 24, 2013 by Anonymous

Chemistry
Q1: You wish to prepare a buffer solution with pH = 11.10. What volume of 6.0 M HCl would you add to 500 mL of 0.10 M (C2H5)2NH to prepare the buffer? You may assume that the solution’s volume remains constant. Q2: What is the resulting pH when 20 mL of 0.20 M NaOH is ...
Sunday, February 24, 2013 by Anonymous

Chemistry
Q1: You wish to prepare a buffer solution with pH = 11.10. What volume of 6.0 M HCl would you add to 500 mL of 0.10 M (C2H5)2NH to prepare the buffer? You may assume that the solution’s volume remains constant. Q2: What is the resulting pH when 20 mL of 0.20 M NaOH is ...
Sunday, February 24, 2013 by David

chemistry
0.50g of mixture of k2c03 and li2c03 requires 30ml of a 0.25N HCL solution for neutralization. What is the percentage composition of the mixture? The answer k2c03 96% The answer li2c03 4% I want Bob step by step explain. I do not still understand x/69 + y/37 = 0.0075 How to ...
Sunday, February 24, 2013 by Fai

Chemistry
Experimentaly discribe how to determine the formula of magnesium.
Sunday, February 24, 2013 by Daniel

Chemistry
Suppose u place a beaker containing a solution in the refrigerator. An hour later, white solid found at thr bottom of beaker, wat hapoened? Why?
Sunday, February 24, 2013 by Ruby

Chemistry
pH pH ( strip c : 8 ) dark green pH ( strip d : 3 ) purple - suppose u mix togather equal amounts of the solutions that produced the results of strip c and d , then test the pH of this new solution. What color will the indicator paper be? Explain .
Sunday, February 24, 2013 by Ruby

chemistry
find work done when 1mole of calcium carbide reats with water to produce acytelene?
Sunday, February 24, 2013 by arpit

Chemistry H
If the pressure on the surface of water in the liquid state is 30 kpa, the water will boil at... 0, 30, 70, or 100 degrees c?
Sunday, February 24, 2013 by lost

Chemistry
One of my homework problems deals with finding the change in entropy of the surroundings using the equation delta(S)= -delta(H)/T(temp.) The numbers given were T=263K and delta(H)fusion=6.0*10^(3) J/mol I know how to solve the problem, I just want to know why it is that even ...
Sunday, February 24, 2013 by Confused

college chemistry
Why is it that sodium chloride or acetic acid can't bee steam distilled??
Sunday, February 24, 2013 by Anonymous

Chemistry
A solution containing 0.100 mol of Na2CO3 and 0.100 mol of NiCl2 is allowed to react. What mass of precipitate forms in this reaction?
Saturday, February 23, 2013 by Eagertolearn

Chemistry
What is(are) the precipitate(s) that form when K2SO4, BaCl2, and AgNO3 solutions are mixed?
Saturday, February 23, 2013 by Jacob

chemistry
Calculate the change in entropy (ΔS˚) of reaction (J/K) for the equation as written. BaCO3(s) → BaO(s) + CO2(g) Table: S° (J/(K mol)) BaCO3(s) = 112 BaO(s) = 70.3 CO2(g) = 213.7 So the answer is -41.7 I thought to find the entropy of reaction you subract ...
Saturday, February 23, 2013 by Carter

chemistry
convert 725mm Hg into equivalent kPa
Saturday, February 23, 2013 by Gerry

chemistry
what pressure would have to be applied to a 27.2 ml sample of gas at 25 Celcius and 1.00atm to compress its volume to 1.ooml without a change in temperature
Saturday, February 23, 2013 by Gerry

Chemistry
Na2CO3 + NiCl2 ¨ NiCO3 + 2NaCl Using the solubility rules determine the solubility of all reactants and products. Explain your answer. I answered Na2 as soluble, Co3 as soluble, NiCl2 as soluble ---->NiCO3 as insoluble, and 2NaCl as soluble. My explanation for the...
Saturday, February 23, 2013 by Eagertolearn

Chemistry
Consider the heterogeneous equilibrium process shown below. C(s) + CO2(g) 2 CO(g) At 700.°C, the total pressure of the system is found to be 3.87 atm. If the equilibrium constant KP is 1.52, calculate the equilibrium partial pressures of CO2 and CO.
Saturday, February 23, 2013 by Alan

chemistry
sometimes,instead of percentage composition, you will have the composition of a mass sample. using the actual mass of the sample, determine the empirical formula for compounds that have the following analyses. b. a 13.07g sample of an unknown substance is composed of 9.48g of ...
Saturday, February 23, 2013 by tula

Chemistry
Consider this equilibrium process at 686°C. CO2(g) + H2(g) CO(g) + H2O(g) The equilibrium concentrations of the reacting species are [CO] = 0.050 M, [H2] = 0.045 M, [CO2] = 0.086 M, and [H2O] = 0.040 M. (a) Calculate Kc for the reaction at 686°C. (b) If the ...
Saturday, February 23, 2013 by Jackie

Chemistry
1. A solution containing 0.100 mol of Na2CO3 and 0.100 mol of NiCl2 is allowed to react. Which reactant is the limiting reactant? 2. A solution containing 0.100 mol of Na2CO3 and 0.100 mol of NiCl2 is allowed to react. How many moles of precipitate form in this reaction?
Saturday, February 23, 2013 by Eagertolearn

chemistry
Consider the following reaction: Na2CO3 + NiCl2 ¨ NiCO3 + 2NaCl Using the solubility rules determine the solubility of all reactants and products. Explain your answer Please. Which product is the precipitate in this reaction? Write the complete ionic equation for ...
Saturday, February 23, 2013 by Eagertolearn

chemistry
8.09% carbon, 0.34% hydrogen, 10.78% oxygen, and 80.78% bromine its similar to the last one i posted empirical formulas
Saturday, February 23, 2013 by tula

Chemistry
At the start of the reaction there are 0.714 mole of H2, 0.984 mole of I2, and 0.886 mole of HI in a 2.70 L reaction chamber. Calculate the concentrations of the gases at equilibrium. The equilibrium constant is 54.3.
Saturday, February 23, 2013 by Amy

Chemistry
At the start of the reaction there are 0.714 mole of H2, 0.984 mole of I2, and 0.886 mole of HI in a 2.70 L reaction chamber. Calculate the concentrations of the gases at equilibrium.
Saturday, February 23, 2013 by Amy

chemistry
2.8% hydrogen, 9.8% nitrogen,20.5% nickel, 44.5% oxygen, and 22.4% sulfur determine empirical formula for compounds
Saturday, February 23, 2013 by tula

Chemistry
A compound which can donate 2 protons is termed dibasic acid. What is the name given to a compound which can accept 2 protons?
Saturday, February 23, 2013 by John

chemistry
One reaction that produces hydrogen gas can be represented by the unbalanced chemical equation Mg(s) + HCl(aq) −! MgCl2(aq) + H2(g) . What mass of HCl is consumed by the reac- tion of 2.96 mol of magnesium? Answer in units of g
Saturday, February 23, 2013 by Anonymous

chemistry
what mass of Fe3O4 would conatin 1.85*10^21 atoms of Fe?
Saturday, February 23, 2013 by rose

chemistry
Calculate the wavelength of a proton with energy 2.45eV. in meter plz
Saturday, February 23, 2013 by schoolgirl

Chemistry
calculate the pH and the propionate ion concentration [c3h502-] of a solution that is .06M in potassium propionate [kc3h502] and .085M in propionic acid [hc3h502]
Saturday, February 23, 2013 by Michael

Chemistry
When 4.54 g of a nonelectrolyte solute is dissolved in 565 mL of water at 29 °C, the resulting solution exerts an osmotic pressure of 835 torr. What is the molar concentration of the solution? How many moles of solute are in the solution? What is the molar mass of the solute?
Saturday, February 23, 2013 by Jim

Chemistry
Suppose u place a beaker containing a solution in a refrigerator , an hr later a white solid is found on thr bottom of thr beaker. What happened. Why? I think a precipitate formed, but can any1 explain briefly so i can understand better? Thanks
Saturday, February 23, 2013 by Mia

Chemistry.
pH C ( dark green) pH : 8 d ( purple) pH : 3 Suppose u mix togather equal amounts of the solutions that produced the results of strip C and strip D , then test the pH of this new solution. What colo will the indicator paper be ? Explain.
Saturday, February 23, 2013 by Mia

Chemistry
This question has been bugging me for a long time. A rock contains a Pb-206 to U-238 mass ratio of .145 to 1.00. Assuming that it did not contain any Pb-206 at the beginning of its formation, determine its age. I assume from the other problems in my book that the 1/2 life is 4...
Saturday, February 23, 2013 by Nancy

chemistry
I have a problem like this: CHCl3 + Cl2 = CCl4 +HCL This is the rate table: CHCL3 Cl2 Initial Rate .010 .010 .0035 .020 .010 .0069 .020 .020 .0098 .040 .040 .027 They want me to find the rate constant and the rate law.
Saturday, February 23, 2013 by Nancy

Plz urgent
Can anyone please answer my chemistry question i posted quick?
Saturday, February 23, 2013 by Mia

Chemistry
pH Strip b = 10. Strip D = 3 what would happen if you mixed togather equal amounts of the solutions that produced the results of strip b and strip d?
Saturday, February 23, 2013 by Mia

Chemistry
Ammonia is composed of hydrogen and nitrogen in a ratio of 9.33 g of nitrogen to 2.00 g of hydrogen. If 2.19 g of nitrogen combined completely with hydrogen to form ammonia, what mass (g) of ammonia would be formed?
Saturday, February 23, 2013 by alex

chemistry
(b) Calculate the amount of zirconium produced (in kg) if a reactor were charged with 310.0 kg and 29.0 kg Na.
Saturday, February 23, 2013 by Anonymous

chemistry
0.50g of a mixture of K2c03 and Li2c03 requires 30ml of a 0.25N hcl solution for neutralization. What is the percentage composition of the mixture? The answer k2c03 96% Li2c03 4% K2c03 weight 138g/mol 138/2 = 69 Li2c03 weight 74g/mol 74/2 = 37 30ml x 0.25N = 7.5 / 1000 x= 0....
Friday, February 22, 2013 by Fai

chemistry
Biphenyl, C12H10, is a nonvolatile, nonionizing solute that is soluble in benzene, C6H6. At 25 °C, the vapor pressure of pure benzene is 100.84 torr. What is the vapor pressure of a solution made from dissolving 11.1 g of biphenyl in 29.1 g of benzene?
Friday, February 22, 2013 by Anonymous

Analytical Chemistry
Phosphoric acid is a triprotic acid with the following pKa values: pka1: 2.148 pka2: 7.198 pka3: 12.375 You wish to prepare 1.000 L of a 0.0100 M phosphate buffer at pH 7.45. To do this, you choose to use mix the two salt forms involved in the second ionization, NaH2PO4 and ...
Friday, February 22, 2013 by Sam

Chemistry
A helium balloon contains 0.54g of helium. Given the molecular weight of helium is 4.0 g/mol, how many moles of helium does it contain?
Friday, February 22, 2013 by Mira

Chemistry
At 25 degrees celsius and 775 Torr, carbon dioxide has a solubility of 0.0347 M in water. What is the solubility at 25 degrees celsius and 1830 Torr
Friday, February 22, 2013 by alyla

Chemistry
pKa1 = 2.148, pKa2 = 7.198, pKa3 = 12.375 You wish to prepare 1.000L of a 0.0100M Phosphate buffer at pH7.55. To do this, you choose to use mix the two salt fomrs involved in the second ionization, NaH2PO4 and Na2HPO4, in a 1.000L volumetric flask and add water to the mark. ...
Friday, February 22, 2013 by Alba

Organic Chemistry
NMR: What can be said about proton spin decoupling? a) It depends on the number of attached protons. b) It slows the deshielding effects of π -electron circulation. c) It is the same as Distortionless Enhancement with Polarization Transfer. d) It is an instrumental ...
Friday, February 22, 2013 by Student

chemistry
A sample of liquid consisting of only C,H and O and having a mass of 0.5438g was burned in pure oxygen and 1.039g of CO2 and 0.6369g H2O were obtained. what is the empirical formula of the compound?
Friday, February 22, 2013 by rose

Analytical Chemistry
Carbon dioxide dissolves in water to form carbonic acid, which is primarily dissolved CO2. Dissolved CO2 satisfies the equilibrium equation. CO2(g) <----> CO2(aq) The acid dissociation constants listed in most standard reference texts for carbonic acid actually apply to ...
Friday, February 22, 2013 by Sam

chemistry
the mass of 2.50 mol of a compound with the formula ECl4, in which E is a nonmetallic element, is 385g. what is the molar mass of Ecl4? what is the identity of E?
Friday, February 22, 2013 by rose

chemistry
the mass of 2.50 mol of a compound with the formula ECl4, in which E is a nonmetallic element, is 385g. what is the molar mass of Ecl4? what is the identity of E?
Friday, February 22, 2013 by rose

chemistry
a sample of glucose, c6h12o6 contains 2.03*10^21 atoms of carbon. (a)how many atoms of hydrogen does it contain? (b)how many molecules of glucose does it contain? (c)how many moles of glucose does it contain? (d)what is the mass of this sample in grams? its kinda long, but i ...
Friday, February 22, 2013 by rose

chemistry
how many grams of CO2 can be formed by the complete combustion of a 14.7 sample of C2H6 that is 92.4% pure?( assume the impurities contain no carbon)
Friday, February 22, 2013 by rose

chemistry
use the following data to calculate the mean bond enthalpy values for the C-H and C-C bonds. CH4(g)-C(g) + 4H(g) standard enthalpy change is +1648 kj/mol C2H6(g)-2C(g) + 6H(g) standard enthalpy change is +2820 kj/mol
Friday, February 22, 2013 by Bliss

CHEMISTRY
WHAT IS THE MEANING OF THE NUMERICAL REPRESENTED BY X IN THE GENERAL FORMULA FOR HYDRATE; SALT H2O?
Friday, February 22, 2013 by PHILASANDE

Chemistry
Heyy Jiskha!! I need ur help today:) Hope you will help:D My question is that why is supersaturation unstable... I read the explanations for this on many websites but for some odd reason I just cannot get it to sink in my mind. What does it mean by it is unstable how is it ...
Friday, February 22, 2013 by Priya

chemistry
At standard temperature, a gas has a volume of 312 mL. The temperature is then increased to 115◦C, and the pressure is held constant. What is the new volume? Answer in units of mL
Thursday, February 21, 2013 by Anonymous

chemistry
difference between solution and pure substance
Thursday, February 21, 2013 by Anonymous

chemistry
calculate the percent by mass of solute in solution that contains 3.85 g of calcium chloride in 78.5g of water
Thursday, February 21, 2013 by Anonymous

Chemistry
How much concentrated solution would you take to prepare 2.80L of 0.475M HCl by mixing with water? Hydrochloric acid is usually purchased in a concentrated form that is 37.0% HCl by mass and has a density of 1.20g/mL.
Thursday, February 21, 2013 by M J

Chemistry
How much concentrated solution would you take to prepare 2.80L of 0.475M HCl by mixing with water?
Thursday, February 21, 2013 by M J

chemistry
how many grams of nitrogen will react with 23 grams of oxygen
Thursday, February 21, 2013 by missy

analytical chemistry
fundamental SI units of: - a distance of exactly 26 miles - an area of 1.0 square root -the volume of a sphere of radius 1.40 picometers -a density of 38. tons per cubic furlong
Thursday, February 21, 2013 by holly

AP Chemistry
Formal charge: When do you use it? How is it calculated?
Thursday, February 21, 2013 by Kenzi

AP Chemistry
Formal charge: When do you use it? How is it calculated?
Thursday, February 21, 2013 by Kenzi

Chemistry
The \rm p \it K_{\rm a} of this reaction is 4.2. In a 0.74\it M solution of benzoic acid, what percentage of the molecules are ionized?
Thursday, February 21, 2013 by Joe

Chemistry
Hydrogen peroxide solution, H2O2(aq), is available with a concentration of 1.667mol/L. When diluted to a concentration of 0.25mol/L, the solution is used as a disinfectant. What volume of water should be added to 100 mL of the concentrated hydrogen peroxide solution to prepare...
Thursday, February 21, 2013 by Lori

Chemistry
A laboratory stockroom has a stock solution of 90%(m/v) sulfuric acid,H2SO4(aq). If a technician dilutes 50ml of the stock solution to a final volume of 300ml, what will be the new mass/volume percent concentration?(HINT: the dilution formula can be used for concentration ...
Thursday, February 21, 2013 by Lori

Chemistry
A 1.0-mL volume of 0.010 M H2SO3 is added to a mixture of 12 drops of 0.010 M HIO3, 8 drops of deionized water, and 1 drop of starch solution. a color change occured after 40 seconds. the rate of reaction is measured by the disappearance of HIO3. got the reaction mixture in ...
Thursday, February 21, 2013 by Anonymous

Chemistry
In a 1.0× 10–4 M solution of HClO(aq), identify the relative molar amounts of these species from most to least: HClO, OCl, OH^-, H30^+, H20
Thursday, February 21, 2013 by Ethan

Chemistry
A 1.0-mL volume of 0.010 M H2SO3 is added to a mixture of 12 drops of 0.010 M HIO3, 8 drops of deionized water, and 1 drop of starch solution. a color change occured after 40 seconds. assuming 25 drops per mL for all solutions, determine the initial molar concentration of HIO3...
Thursday, February 21, 2013 by Anonymous

chemistry
how many c atoms are contained in 15.63g of c5h12??
Thursday, February 21, 2013 by rose

college chemistry
how to make a 1:8 dilution of chemical Y. You have 350 mililiters of chemical Y. how much diluent do you need?
Thursday, February 21, 2013 by chuck

English
This is a chemistry lab report, but I was wondering if someone could edit the grammar and look at the sentence structure, etc. I know it's really long and boring, but even if you just look over a bit of it, I would really appreciate it. And I'm assuming you don't ...
Thursday, February 21, 2013 by a Canadian

chemistry
A sample of liquid consisting of only C,H and O and having a mass of 0.5438g was burned in pure oxygen and 1.039g of CO2 and 0.6369g H2O were obtained. what is the empirical formula of the compound?
Thursday, February 21, 2013 by rose

chemistry
A solution is prepared by mixing 50.7 mL of 0.28 M Pb(NO3)2 with 70.8 mL of 1.0 M KCl. Calculate the concentrations of Pb2+ and Cl - at equilibrium. Ksp for PbCl2(s) is 1.6 10-5.
Thursday, February 21, 2013 by jeff

chemistry
"empirical formulas" p 889(153e)
Thursday, February 21, 2013 by rose

Chemistry
I had a quiz today and one of the multiple choice questions was something like, "find the final temperature of aluminum when it is cooled" and then it gave you the specific heat capacity of aluminum, the mass of the aluminum, initial temperature, and enthalpy change...
Thursday, February 21, 2013 by a Canadian

chemistry
"empirical formulas" combustion of a 0.255g compound conatining only C,H and O, yields 0.561g CO2 and 0.306g H2O. what is the empirical formula of the compound?
Thursday, February 21, 2013 by rose

chemistry
In the reaction Mg(s) + 2HCl(aq) d H¿(g) + MgCl¿(aq), how many moles of hydrogen gas will be produced from 250.0 milliliters of a 3.0 M HCl in an excess of Mg?
Thursday, February 21, 2013 by Payton

chemistry
A 2.50g sample of a hydrate of calcium nitrate was heated, and only 1.70g of the anhydrous salt remained. what is the formula of the hydrate?
Thursday, February 21, 2013 by rose

chemistry
what mass of carbondioxide would be produced if 500g of ethane is used?
Thursday, February 21, 2013 by williamz

chemistry
a 5.00g sample of a hydrate of barium chloride was heated, and only 4.30g of the anhydrous salt remained. what is the formula of the hydrate?
Thursday, February 21, 2013 by rose

analytical chemistry
your lab possesses a stock solution of NaOH whose concentration is approx. 0.1M. you prepare a secondary solution by diluting 15.00mL of this stock solution to a total volume of 250.0 mL. you titrate a 50.00mL aliquot of the secondary solution with a hydrochloric acid solution...
Thursday, February 21, 2013 by holly

chemistry
A solution contains 2 mEq/ml of KCL (Molecular weight 74.5). If a 20 ml ampule of this solution is diluted to 1 liter what is the percent strength of the resulting solution?
Thursday, February 21, 2013 by Ann

Chemistry - Mass-Mass conversion & Percent yield
Please show work 1. N2 (g) + 3H2(g) ---> 2NH3(g) 100.0 g of nitrogen reacts completely with excess hydrogen, and 34.0 g of NH3 are obtained what is the percent yield of ammonia? 2. 2Al (s) + 3Cl2(g) ---> 2AlCl3(s) Assume that 0.40 g of Al is mixed with 0.60 g Cl2. (a) ...
Thursday, February 21, 2013 by Anonymous

chemistry
if 125g of magnesium sulfate heptahydrate is completely dehydrated, how many grams of anhydrous salt will remain? i would really appreciate anyone's help
Thursday, February 21, 2013 by rose

chemistry
what is the formula for the sodium sulfate if 3.54g of dry solid remain after 8.50g of hydrate are heated??
Thursday, February 21, 2013 by rose

chemistry
How do you find q in q=mC delta t without the mass
Thursday, February 21, 2013 by Jake

chemistry
How many atoms are in 10.0 cm3 of mercury (at room temperature)?
Thursday, February 21, 2013 by adex

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