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April 28, 2016

Homework Help: Science: Chemistry

Recent Homework Questions About Chemistry

chemistry
write the balanced equation for the reactions of aquesous pb(CIO3)2 with aqueous Nal. include phases. 2.If a solution containing 86.044 g of mercury(II) chlorate is allowed to react completely cointaing 15.4888 g of sodium sulfide, how many grams of solid precipate will be ...
Tuesday, September 24, 2013 by christina

Chemistry
2 NaN3(s) = 2 Na(l) + 3 N2(g) How many grams of NaN3 are needed to produce 20L of N2(g) at 303K and 776mmHg?
Tuesday, September 24, 2013 by Nancy

Chemistry
Convert 1.46 mm to inches.
Tuesday, September 24, 2013 by Joli

12th grade chemistry
What is the structure for ethyl ethanamide? (Ie. c-c-N-c-c) ??? Thanks
Tuesday, September 24, 2013 by Michaela

Chemistry
There are two flask, one filled with a)ice bath, and b)boiling water. Ice bath: 1.00 L O^2(g) at STP Boiling water: 1.00 O^2(g) If we want the pressure to remain at 1.00bar when the O^2(g) is heated to 373K, what mass of O^2 must we release from the flask? I know that I should...
Tuesday, September 24, 2013 by Mae

Chemistry
which is more accurate direct weighting or weighing by difference?
Tuesday, September 24, 2013 by Justin

Chemistry
Microwave ovens emit microwave energy with a wavelength of 12.5 cm. What is the energy of exactly one photon of this microwave radiation?
Tuesday, September 24, 2013 by Kiana

chemistry
A 6.25 gram sample of copper(II) chloride hydrate was heated until all the water was liberated. The residue massed 4.45 grams. How many water molecules are present for every formula unit of copper(II) chloride?
Tuesday, September 24, 2013 by Peytreshia

Chemistry
Upon heating 8.5g sample of Sodium Sulfate hydrate, it loses 4.776 grams after heating. What steps are necessary for me to find the n for the hydrate? GIVEN: Na2SO4 - n H2O the molar mass of sodium sulfate is 142.05g/mol
Tuesday, September 24, 2013 by Peytreshia

Chemistry
If 4.00 grams of the hydrate in #1 are heated how many grams of anhydrous salt would remain after all the water was liberated?
Tuesday, September 24, 2013 by sTin

Chemistry
Select the statements that correctly describe buffers.? 1) The pH of a buffer solution does not change significantly when any amount of a strong acid is added. 2) The Ka of a buffer does not change when any amount of an acid is added to the buffer solution. 3) The pH of a ...
Monday, September 23, 2013 by Aria

chemistry
A laser pulse with wavelength 540 nm contains 4.40 Mj of energy. How many photons are in the laser pulse?
Monday, September 23, 2013 by Anonymous

Chemistry
If a student used an iron scoopula, instead of a plastic one, to add the unknown metal to the HCl solution, will it affect the calculated molar mass of the unknown metal? If so, how? Justify your answer with an explanation.
Monday, September 23, 2013 by Ella

Chemistry
Can calcium hydroxide solution be used to distinguish Co(NO3)2 and Fe(NO3)3 solutions using only the titration technique? Justify your answer with an explanation.
Monday, September 23, 2013 by Ella

AP Chemistry
redox reaction: Hydrogen peroxide is added to an acidified solution of potassium permanganate. what is the total redox reaction?
Monday, September 23, 2013 by Gabriella

Chemistry
Table salt, NaCl, and sugar C12H22O11 are accidentally mixed. A 5.50g sample is burned and 3.60g of CO2 is produced. What was the mass percentage of the table salt mixture?
Monday, September 23, 2013 by Andrew

chemistry
Which of the following is a precipitation reaction? I. 2 Mg (s) + O2 (g) → 2 MgO (s) II. SO3 (g) + 2 H2O (l) → H3O+ (aq) + HSO4- (aq) III. Pb2+ (aq) + CrO42- (aq) → PbCrO4 (s) IV. 2 H2O (g) → 2 H2 (g) + O2 (g) V. Ag+ (aq) + 2 NH3 (aq) → [Ag(NH3)2...
Monday, September 23, 2013 by sos

Chemistry
How many moles of H2O are in 3.00L of water? (d=1.00g/mL)
Monday, September 23, 2013 by Cassandra

chemistry
the density aniline c6h5nh2 is 1.02g/mL how many molecules are present in 1.00Lsample
Monday, September 23, 2013 by Anonymous

Chemistry
A sample of impure magnesium was analyzed by allowing it to react with excess HCl solution: Mg(s) + 2 HCl(aq) → MgCl2(aq) + H2(g) After 1.27 g of the impure metal was treated with 0.100 L of 0.768 M HCl, 0.0125 mol HCl remained. Assuming the impurities do not react, what...
Sunday, September 22, 2013 by James

chemistry
Use Henry's law to determine the molar solubility of helium at a pressure of 1.2atm and 25 ∘C. Express your answer using two significant figures.
Sunday, September 22, 2013 by Anonymous

Chemistry
Acetylsalicylic acid (C9H8O4) is a monoprotic acid commonly known as "aspirin." A typical aspirin tablet, however, contains only a small amount of the acid. In an experiment to determine its composition, an aspirin tablet was crushed and dissolved in water. It took ...
Sunday, September 22, 2013 by Anonymous

Chemistry
When calcium carbonate is added to hydrochloric acid, calcium chloride, carbon dioxide, and water are produced. CaCO3 +2HCl yields CaCl2 +H2O +CO2 How many grams of calcium chloride will be produced when 29.0 g of calcium carbonate are combined with 13.0 g of hydrochloric acid...
Sunday, September 22, 2013 by Lori

Chemistry- is this correct?
34 meters/seconds = _____ mm/hour I know 1 m is 1000 mm and 60 seconds is 1 hour. So I got 2040000. Would the answer in scietnific notation and significant figures be 2.0 x 10^6 mm/hour?
Sunday, September 22, 2013 by Anonymous

Chemistry
What volume of 0.01 M NaOH should be required to raise the pH of a litre of 25 mM H2SO4 to 4.0? I started out by attempting to find the initial pH of H2SO4 and determined I need 2.57 units of pH to raise it to 4. I know that somewhere I use the HH equation, but don't know ...
Sunday, September 22, 2013 by Sara

Chemistry
Please Explain! I dont understand how the answer is B. Which ionization requires the most energy? A. Na--> Na superscript + plus one electron B. Na superscript + -----> Na superscript 2+ plus one electron C. Mg---> Mg superscript + plus one electron D. Mg superscript...
Sunday, September 22, 2013 by Anonymous

Chemistry
In four of the following groups, the three substances are either all strong electrolytes, all weak electrolytes, or all nonelectrolytes. Which group has one member which is NOT like the others in the group? 1. NaCl; Ca(OH)2; HNO3 2. BaCl2; NaNO3; HF 3. O2; CO(NH2)2; CH3OH 4. ...
Sunday, September 22, 2013 by Claire :)

Chemistry
Which of the following metals or nonmetals are expected to displace Mn or Cl (respectively) from MnCl2? 1. Ca should displace Mn. 2. Br should displace Cl. 3. Cu should displace Mn. 4. I should displace Cl.
Sunday, September 22, 2013 by John

Chemistry Graphing
So for Chem we have to answer a question asking why graphing is a more accurate method for measuring density than manually calculating the density. I originally thought that manually calculating was better, but my teacher told me that I would have to back that up with a lot of...
Sunday, September 22, 2013 by Anonymous

Chemistry
If aqueous hydrofluoric acid is reacted with sodium hydroxide, which of the following substances are in the net ionic equation? 1. hydrofluoric acid, hydroxide ion, hydronium ion, fluoride ion, and water 2. hydrofluoric acid, sodium ion, hydroxide ion, ...
Sunday, September 22, 2013 by Adam

chemistry
Table salt, NaCl(s), and sugar, C12H22O11(s), are accidentally mixed. A 4.00-g sample is burned, and 3.30 g of CO2(g) is produced. What was the mass percentage of the table salt in the mixture?
Sunday, September 22, 2013 by Jessica

Chemistry
calculate q , w , and ∆ E for melting 1.00 mol of ice at 0 ◦ C and 1.00 atm pressure
Sunday, September 22, 2013 by C

Chemistry
A vessel containing 39.5 cm3 of helium gas at 25°C and 106 kPa was inverted and placed in cold ethanol. As the gas contracted, ethanol was forced into the vessel to maintain the same pressure of helium. If this required 18.8 cm3 of ethanol, what was the final temperature ...
Sunday, September 22, 2013 by Hannah

Chemistry
The combustion of ethane (C2H6) produces carbon dioxide and steam: 2C2H6+702 yields 4CO2 +6H2O How many moles of CO2 are produced when 5.30 mol of ethane are burned in an excess of oxygen?
Sunday, September 22, 2013 by Mary

question
is it better to take physics or chemistry if taking both whats better to take 1st in sophomore year better to take ap statistics or precalculas for becoming an architect
Sunday, September 22, 2013 by jim

chemistry
what is the name of reaction for 3C2H2--> C6H6?
Sunday, September 22, 2013 by hi

Physical Chemistry
Integrate the expression β = 1/V (δV / δT) at constant pressure, assuming that β is independent of temperature. By doing so, obtain an expression for V as a function of T and β at constant P.
Sunday, September 22, 2013 by Brittney

Science/ Chemistry
When 0.422 g of phosphorus is burned, 0.967 g of a white oxide (a compound of phosphorus and oxygen) is obtained. a. Determine the empirical formula of the oxide. So for the empirical Formula I got P_2O_5 now it wants me to Write a balanced equation for the reaction of ...
Sunday, September 22, 2013 by James

Chemistry
How many sulfate ions are there in 2.500 mL of 5.0 x 10-15 moles of Cr2(SO4)3?
Sunday, September 22, 2013 by Zac

Chemistry
Calculate the cohesive energy of potassium iodide (KI). The ionic radii of K+ and I−, are 152 pm and 206 pm, respectively. Assume the Born exponent n is 10. Assume a Madelung constant of 1.7. Please report your answer in kJ/mol.
Sunday, September 22, 2013 by walter white

Chemistry
What is the energy of a bond formed between a potassium (K+) cation and an iodide (I−) anion? The ionic radii of K+ and I−, are 152 pm and 206 pm, respectively. Assume the Born exponent n is 10. Please report your answer in joules.
Sunday, September 22, 2013 by walter white

Chemistry
What is the energy of a bond formed between a potassium (K+) cation and an iodide (I−) anion? The ionic radii of K+ and I−, are 152 pm and 206 pm, respectively. Assume the Born exponent n is 10. Please report your answer in joules.
Sunday, September 22, 2013 by walter white

Chemistry
Provide the products for this reaction: CH3O- +CH3SH -> ????
Sunday, September 22, 2013 by Anon.

Chemistry
Why does aniline turn brown upon standing? Does it also turn brown upon heating?
Sunday, September 22, 2013 by John

Chemistry
The half life of U238 is 4.5 x 10^9 yr. A sample of rock of 1.6 g produces 29 dis/sec. Assuming all radioactivity is due to U238 find percent by mass of U 238. I have tried ln(t)/ln(0)= -kt and still cannot get the answer What I get is A) 4.5x10^9 x365x60x60x24=1.419x10^17 for...
Sunday, September 22, 2013 by Nancy

Chemistry
When electrons get excited can they only move up one level or can they go up multiple orbitals, but just one at a time.
Saturday, September 21, 2013 by Serena

Chemistry
An element with the symbol Z has the electron configuration 2.8.6. Which species is this elrment most likely to form? A. The ion Z 2+ B. The ion Z 6+ C. The compound H subscript 2 Z D. The compound Z subscript 6 F Which ionization requires the most energy? A. Na--> Na ...
Saturday, September 21, 2013 by Anonymous

chemistry
The radius of a aluminum atom is 143 pm. How many aluminum atoms would have to be laid side by side to span a distance of 4.90 mm?
Saturday, September 21, 2013 by sabrina

Chemistry
The standard internal energy change for a reaction can be symbolized as ΔU°rxn or ΔE°rxn. For the following reaction equations, calculate the energy change of the reaction at 25 °C and 1.00 bar. Sn(s) + 2Cl2(g) --> SnCl4(l) ΔH°rxn = -511.3 kJ/...
Saturday, September 21, 2013 by Anonymous

Chemistry
Please help! I have spent hours trying to work these three problems. How many grams of solid barium sulfate form when 27.1 mL of 0.160 M barium chloride reacts with 53.4 mL of 0.065 M sodium sulfate? Aqueous sodium chloride forms also. I have converted the 27.1mL to .0271L, ...
Saturday, September 21, 2013 by Anonymous

Chemistry
Consider the following reaction: 2Fe2O3 --> 4Fe + 3O2 ∆Hrxn° = +824.2 kJ The decomposition of 29.0 g of Fe2O3 results in a. the release of 150 kJ of heat b. the release of 12000 kJ of heat c. the absorption of 12000 kJ of heat d. the absorption of 150 kJ of heat e...
Saturday, September 21, 2013 by Anonymous

Chemistry
A1g sample of enriched water, a mixture of H2O AND D2O, reacted completely with Cl2 to give a mixture of HCl and DCl. The HCl and DCl were then dissolved in pure H2O to make a 1.00 L solution. A 25.00 mL, sample of the 1 L solution was reacted with excess AgNO3 and 0.3800g of ...
Saturday, September 21, 2013 by Anirudh

chemistry
A particle with the mass of a proton is trapped in a box. The particle falls from the n=3 state to the n=2 state and emits 0.16 meV of energy. What is the size of the box? Please report your answer in nm.
Saturday, September 21, 2013 by sam

Chemistry
What is the maximum mass of S8 that can be produced by combining 85.0 g of each reactant? 8SO2 + 16H2S yields 3S8 +16H2O
Saturday, September 21, 2013 by James

Chemistry
An unknown compound contains only C, H, and O. Combustion of 4.50 g of this compound produced 10.2 g of CO2 and 4.19 g of H2O. What is this empirical formula of the unknown compound?
Saturday, September 21, 2013 by Casey

chemistry
Butane gas, C4H10(g), is commonly used as a fuel in barbeque gas cylinders. Write a balanced chemical equation for the combustion of butane gas
Saturday, September 21, 2013 by jeannet

Chemistry.........
Elemental chlorine exists as a diatomic molecule Cl2. Chlorine atoms exist in two different isotopes 35Cl and 37Cl. In the mass spectrum of chlorine molecules, how may peaks due to chlorine atoms would be observed? 2 how many different peaks due to the molecular ion would be ...
Saturday, September 21, 2013 by Anonymous

Chemistry
Calculate the cohesive energy of potassium iodide (KI). The ionic radii of K+ and I−, are 152 pm and 206 pm, respectively. Assume the Born exponent n is 10. Assume a Madelung constant of 1.7.
Saturday, September 21, 2013 by ss01

Chemistry
What is the energy of a bond formed between a potassium (K+) cation and an iodide (I−) anion? The ionic radii of K+ and I−, are 152 pm and 206 pm, respectively. Assume the Born exponent n is 10
Saturday, September 21, 2013 by ss01

Chemistry
A sample of 2.08 grams of Z is dissolved into 500 grams of water which is in a styrofoam coffee cup. The temperature is monitored and is found to rise from 25.682◦C to 25.899◦C. What is ∆Hsolution for substance Z? Assume no heat is lost/gained by the ...
Saturday, September 21, 2013 by John

Chemistry stoch1
Calculate mass of iron, which will be converted into (Fe3O4) by the action of 18g of steam on it.
Saturday, September 21, 2013 by Aman

Chemistry
A sample of glucose, C6H12O6, contains 5.1x10623. a.)How many atoms of hydrogen does it contain? b.)How many molecules of glucose does it contain? please help me. :(
Saturday, September 21, 2013 by Rad

Chemistry
A sample of glucose, C6H12O6, contains 5.1x10623. a.)How many atoms of hydrogen does it contain? b.)How many molecules of glucose does it contain? please help me. :(
Saturday, September 21, 2013 by Rad

chemistry
You suspect your trophy for the “Freshman Chemistry Award” of mass 122.6 g is not composed of pure gold and you decide to test this by immersing the trophy into a graduated cylinder containing a liquid shown in Fig. 2A. The result is shown in Fig. 2B. Is your trophy ...
Friday, September 20, 2013 by Katie Jones

Chemistry
What is the binding energy of 1 mole of 239/94 Pu if the mass defect is 0.001896 kg/mol?
Friday, September 20, 2013 by Abbie

chemistry
you wish to calculate the mass of hydrogen gas that can be prepared from 4.89 g of SrH2 and 5.28 g of H2O. (a) How many moles of H2 can be produced from the given mass of SrH2?
Friday, September 20, 2013 by Anonymous

quantitative chemistry
How do you write an expression for the mass of the residue in terms of x and y?
Thursday, September 19, 2013 by Lost

quantitative chemistry
How do you write an expression for the mass of the residue in terms of x and y?
Thursday, September 19, 2013 by Lost

Chemistry
Calculates the work done (in joules) when 42.8 g of tin dissolves in excess acid at 1.10 atm and 23 degrees Celcius. Assume ideal gas behaviour.
Thursday, September 19, 2013 by Vanessa

Chemistry
Calculates the work done (in joules) when 42.8 g of tin dissolves in excess acid at 1.10 atm and 23 degrees Celcius. Assume ideal gas behaviour.
Thursday, September 19, 2013 by Vanessa

chemistry
A graduated cylinder contains 155mL mL of water. A 17.0g g piece of iron (density = 7.86g/cm 3 g/cm^3 ) and a 23.0g g piece of lead are added. What is the new water level in the cylinder?
Thursday, September 19, 2013 by uta

quantitative chemistry
How do you write an expression for the mass of the residue in terms of x and y?
Thursday, September 19, 2013 by Lost

Chemistry
How many atoms are 3.75 moles of iron (Fe)?
Thursday, September 19, 2013 by anony5

Math
Post a New Question Current Questions Homework Help: Math (HELP PLEASE) Posted by Anonymous on Tuesday, September 17, 2013 at 8:37pm. Estimate the total precipitation in inches and in days for Asheville and Wichita. City: Inches: Days...
Thursday, September 19, 2013 by I need help on this to

Chemistry
Technetium-99m is an ideal radioisotope for scanning organs because it has a half-life of 6.0 hr and is a pure gamma emitter. Suppose that 200mg were prepared in the technetium generator this morning. How many milligrams would remain after the following intervals? 1- One half ...
Thursday, September 19, 2013 by Nadia

General Chemistry
The enthalpy of vaporization of benzene liquid is 33.9 kJ/mol at 298 K. How many liters of benzene gas, measured at 298 K and 95.1 mmHg, are formed when 1.54 kJ of heat is absorbed by benzene liquid at a constant temperature of 298 K? I think we use the ideal gas law, but I&#...
Thursday, September 19, 2013 by <3

Chemistry
Technetium-99m is an ideal radioisotope for scanning organs because it has a half-life of 6.0 hr and is a pure gamma emitter. Suppose that 200mg were prepared in the technetium generator this morning. How many milligrams would remain after the following intervals? 1- One half ...
Thursday, September 19, 2013 by Nadia

chemistry
190 grams of potassium iodide is placed in 100 cm3 at 60 degrees Celsius. the solution is cooled to 30 degrees Celsius. how many grams will settle out?
Thursday, September 19, 2013 by Cara

chemistry
How many grams of O2(g) are needed to completely burn 24.0 g of C3H8(g)?
Thursday, September 19, 2013 by college chem

chemistry
How many grams of Cl are in 525 g of CaCl2?
Thursday, September 19, 2013 by college chem

chemistry
Complete combustion of 4.80 g of a hydrocarbon produced 15.6 g of CO2 and 4.80 g of H2O. What is the empirical formula for the hydrocarbon?
Thursday, September 19, 2013 by college chem

chemistry
calculate the percentage copper in copper 2 nitrate
Thursday, September 19, 2013 by Anonymous

Chemistry
How many grams of sodium sulphate (mol. wt. 142) are required to make 1.2 liters of 0.5N solution
Thursday, September 19, 2013 by Frank

Chemistry
A solution containing 0.750g of an unknown substance in 30.0g of cyclohexane was found to freeze at 3.1 degree Celsius. What is the molar mass of the unknown substance?
Thursday, September 19, 2013 by Princess

Chemistry
If 10.11 g of limestone decomposes by heat to give 8.51 g of solid calcium oxide and carbon dioxide gas, what is the mass of carbon dioxide produced?
Thursday, September 19, 2013 by Caleb

Chemistry
What is the energy of a bond formed between a potassium (K+) cation and an iodide (I−) anion? The ionic radii of K+ and I−, are 152 pm and 206 pm, respectively. Assume the Born exponent n is 10. Please report your answer in joules. x=
Thursday, September 19, 2013 by Urgent help

Chemistry
a large amount of potassium in plant food could cause the formation of MgKPO4:6H2O along with MAPH. what would be the effect on the calculated percentage of P2O5 in question 1 if MAPH were mixed in with your precipitate? would the %P2O5 in this mixture be higher or lower than ...
Thursday, September 19, 2013 by dave

Chemistry
What is the energy of a bond formed between a potassium (K+) cation and an iodide (I−) anion? The ionic radii of K+ and I−, are 152 pm and 206 pm, respectively. Assume the Born exponent n is 10. Please report your answer in joules. x=
Thursday, September 19, 2013 by Urgent help

Chemistry
What is the energy of a bond formed between a potassium (K+) cation and an iodide (I−) anion? The ionic radii of K+ and I−, are 152 pm and 206 pm, respectively. Assume the Born exponent n is 10. Please report your answer in joules. x= Calculate the cohesive energy ...
Wednesday, September 18, 2013 by Urgent help

Chemistry
What is the energy of a bond formed between a potassium (K+) cation and an iodide (I−) anion? The ionic radii of K+ and I−, are 152 pm and 206 pm, respectively. Assume the Born exponent n is 10. Please report your answer in joules. x= Calculate the cohesive energy ...
Wednesday, September 18, 2013 by Urgent help

Chemistry
Why is it suggested you use weighing paper or a watch glass instead of filter paper on which to allow a sample to dry? Please give two examples.
Wednesday, September 18, 2013 by Maria

Chemistry
Calculate the wavelength of a proton with energy 2.45 eV. Please some help!
Wednesday, September 18, 2013 by Anon

Chemistry
Technetium-99m is an ideal radioisotope for scanning organs because it has a half-life of 6.0 hr and is a pure gamma emitter. Suppose that 200mg were prepared in the technetium generator this morning. How many milligrams would remain after the following intervals? 1- One half ...
Wednesday, September 18, 2013 by Nadia

chemistry
What mass of nitric acid, in grams, can be made from 113g g of ammonia?
Wednesday, September 18, 2013 by keisha

chemistry
an ideal gas in a sealed container has an initial volume of 2.70L. at constant pressure, it is cooled to 25.00 C where its final volume is 1.75L. what was the initial temperature?
Wednesday, September 18, 2013 by Anonymous

Chemistry
Calculate the volume of hydrogen, in L, produced when 12.15 g of magnesium react completely with water. Assume S..T.P.
Wednesday, September 18, 2013 by Carlene

chemistry
how to make 3.0 liters of a 0.98 molar HCl solution from a 10.5 molar HCl stock solution.
Wednesday, September 18, 2013 by florence

chemistry
Which metal can be obtained form the ore by heating alone Can you pls write down the word equations for these
Wednesday, September 18, 2013 by kim jung hee

chemistry
What is the energy of a bond formed between a potassium (K+) cation and an iodide (I−) anion? The ionic radii of K+ and I−, are 152 pm and 206 pm, respectively. Assume the Born exponent n is 10. Please report your answer in joules. x= Calculate the cohesive energy ...
Wednesday, September 18, 2013 by Urgent help

Chemistry
From a laboratory process designed to separate water into hydrogen and oxygen gas, a student collected 11.6 g of hydrogen and 65.9 g of oxygen. How much water was originally involved in the process? don't understand how to work it out
Tuesday, September 17, 2013 by aaliyah

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Homework Help: Science