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November 20, 2014

Homework Help: Science: Chemistry

Recent Homework Questions About Chemistry

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Chemistry
Does anyone know a website with practice problems (and answers) regarding quantitative chemistry? I haven't been able to find anything on Google.
Wednesday, October 15, 2014 at 9:36pm

Chemistry
Calculate the mass of water having the same number of hydrogen atoms as are present in 32 gm of methane.
Wednesday, October 15, 2014 at 9:32pm

CHEMISTRY
Balance the following equation. (for a balanced eq. aA + bB → cC + dD, enter your answer as the integer abcd) CrO42−(aq) + H2O(l) + HSnO2− → CrO2−(aq) + OH−(aq) + HSnO3−(aq)
Wednesday, October 15, 2014 at 9:01pm

Chemistry
What volume of CO2 gas is produced when 20 gm of 20% pure CaCO3 is completely heated?
Wednesday, October 15, 2014 at 8:57pm

Chemistry
a 191 g piece of copper is heated to 100 C in a boiling water bath and then dropped into a beaker containing 755 g of water (density =1.00 g/cm3) at 4.0 C. What is the final temperature of the copper and water after thermal equilibrium is reached? (Scu=0.385 J/g•K)
Wednesday, October 15, 2014 at 8:22pm

chemistry
source of errors in determining transport number of k+ ion by moving boundary method
Wednesday, October 15, 2014 at 4:58pm

chemistry
Sodium chloride is formed by the following reaction: NaOH + HCl --> NaCl + H2O How many grams of water are formed when 10 g of HCl is consumed? Round your answer to one decimal place, do not include units or commas. use the molar masses in your text to two decimal places.
Wednesday, October 15, 2014 at 4:00pm

chemistry
A mixture containing 15 g of carbon and 25 g of oxygen is sealed in a flask. The total mass of the system is 140 g. The flask is then heated to cause the carbon and oxygen to react. The sealed flask is then weighed. What is the final weight of the system?
Wednesday, October 15, 2014 at 2:20pm

chemistry
Describe how to make 450mL of a 1.15% solution of CuSO4
Wednesday, October 15, 2014 at 10:40am

chemistry
How many grams of NaOH are contained in 5.0 × 102 mL of a 0.77 M sodium hydroxide solution? The molar mass of NaOH is 40.0 g/mol.
Wednesday, October 15, 2014 at 2:36am

Introductory Chemistry
Calcium chloride is 36.11% calcium by mass. How many grams of calcium are in 40.0 grams of calcium chloride
Wednesday, October 15, 2014 at 2:07am

Chemistry
A hot air balloon is filled with 1.31 × 106 L of an ideal gas on a cool morning (11 °C). The air is heated to 129 °C. What is the volume of the air in the balloon after it is heated? Assume that none of the gas escapes from the balloon.
Tuesday, October 14, 2014 at 10:25pm

chemistry
if you have 125.0g of water at 100.0, how much energy must be added to vaporize all of it
Tuesday, October 14, 2014 at 9:42pm

Chemistry
The speed of light in a vacuum is 2.998 x 10^8 m/s. What is the speed of light in miles per hour? (1 km = 06214 miles)
Tuesday, October 14, 2014 at 9:27pm

Separation of Racemate- Chemistry Lab
Compare the relative reaction rates of 1-bromobutane, 2-bromopropane, and 2-bromomethylpropane under SN1 reaction conditions. Silver nitrate will be used to provide nitrate ion as the nucleophile to produce alkyl nitrates as products. 1) I found the answer for this one. 2) You...
Tuesday, October 14, 2014 at 9:08pm

chemistry
When 1.933 g of KNO3 is dissolved in 200 g of water initially at 23.57 ¢ªCelsius in a coffee-cup calorimeter, the final temperature is found to be 22.63 ¢ªCelsius. Calculate the heat released/absorbed per gram of KNO3 and per mol of KNO3 when KNO3 dissolves...
Tuesday, October 14, 2014 at 8:54pm

chemistry
how could solid magnesium phosphate be prepared and collected using hydrochloric acid, sodium phosphate solution, water and magnesium? For the answer, write a series of steps that describe the procedure and includes a balanced chemical equation for each step
Tuesday, October 14, 2014 at 8:40pm

Chemistry
A 32.3-L of a gas at 30 degrees Celsius and 1.20 atm is to be cooled at constant pressure until its volume becomes 28.4 L. What will be the new gas temperature?
Tuesday, October 14, 2014 at 8:22pm

chemistry
When 2.5g of ammonium dichromate is heated, the mass of nitrogen and water vapor released is 1.0g. What is the final mass of the solid product?
Tuesday, October 14, 2014 at 7:53pm

Separation of Racemate- Chemistry Lab
Compare the relative reaction rates of 1-bromobutane, 2-bromopropane, and 2-bromomethylpropane under SN1 reaction conditions. Silver nitrate will be used to provide nitrate ion as the nucleophile to produce alkyl nitrates as products. 1) You have a choice of acetone or ethanol...
Tuesday, October 14, 2014 at 7:36pm

chemistry
Calcium metal is heated with oxygen gas to yield calcium oxide.
Tuesday, October 14, 2014 at 7:31pm

Grade 9 Chemistry
which is more reactive k or ca? ( from periodic table.) when poured in water?
Tuesday, October 14, 2014 at 6:56pm

Chemistry
Predict the physical properties and relative reactivity of Rb, Cs, and Fr (From the periodic table)
Tuesday, October 14, 2014 at 6:13pm

Chemistry
A pure copper sphere ha a radius of 0.935in. How many moles of copper does it contain? The volume of a sphere is (4/3)3.14r^3, and the density of the copper is 8.96g/cm^3. (1 in. = 2.54cm)
Tuesday, October 14, 2014 at 1:49pm

Chemistry
I was doing a lab and stared off with 10mL of HNO3 and the mass of copper which was 1.5120g. The question now is: With initial mass of copper wire being 1.5120g, calculate the volume of (16M) nitric acid that is required to fully react with the copper. Cu(s)+2HNO3(aq) --> ...
Tuesday, October 14, 2014 at 9:16am

Chemistry
Hi was looking to get some help with an experiment. Currently I trying to determine the amount iron in cereal. And was hoping to get some help with one of the questions I have been given. First off I am the recorded absorbance across the region 470 – 490 nm for the 3.00 ...
Tuesday, October 14, 2014 at 9:12am

Chemistry
How many moles of solid Mg(OH)2 should you add to 200mL of 0.15M lactic acid solution to produce pH 4.0 buffer? -I don't know how to do this w/0 knowing pKa, but I don't think the point is to look up pKa. Is there some other way to solve this?
Tuesday, October 14, 2014 at 4:28am

Chemistry
Do you expect CaCl(s) to be stable if the 1st ionization energy of Calcium is approx. 590 kj/mol, the Lattice Energy is approx 700 kj/mol and the total change in enthalpy is -36? Why?
Tuesday, October 14, 2014 at 1:44am

chemistry
A solution of sodium thiosulfate, Na2S2O3, is 0.4206 M. 28.94 mL of this solution reacts with 5.89 mL of I2 solution. What is the molarity of the I2 solution?
Tuesday, October 14, 2014 at 12:22am

chemistry
How long does it take light to travel each of the following distances 2462 mi, the distance between Los Angeles and New York. How do we calculate how fast light travels?
Monday, October 13, 2014 at 11:00pm

Chemistry 30
Calculate the delta H for the reaction : 2H3BO3(aq) reacts with B2O3(solid) + 3H2O
Monday, October 13, 2014 at 10:18pm

chemistry
A mixture containing 2.81 g each of CH4 (g), C2H4 (g) and C4H10 (g) is contained in a 1.50 L flask at a temperature of 35 oC. What is the partial pressure (in atm) of C4H10 (g)?
Monday, October 13, 2014 at 9:00pm

chemistry
What mass (in gram of air) is filled in a hot balloon when it is finflated (at 95oC) to a volume of 500 L at 1.15 atm? (The average molar mass of air is 29 g/mol)
Monday, October 13, 2014 at 8:41pm

chemistry
You have prepared 20.00 mL of a buffer, using 4.00 mL 0.010 M HA (weak acid) and 3.00 mL 0.010 M NaA (provides A-, the conjugate base of HA). pKa for HA is 6.25. How many moles of HA will be present in the mixture after addition of 0.20 mL 0.010 M NaOH?
Monday, October 13, 2014 at 8:08pm

Chemistry
How many moles of solid Mg(OH)2 should you add to 200mL of 0.15M lactic acid solution to produce pH 4.0 buffer?
Monday, October 13, 2014 at 7:54pm

chemistry/toxicology/instrumental analysis
A standard curve was produced using absorbance values of prepared standards obtained by UV spectrophotometry. The standards were made using concentrated hydrochloric acid as opposed to the 1N HCl that the lab manual says should be used. Because of this my absorbance values are...
Monday, October 13, 2014 at 7:50pm

chemistry
what is the final M solution prepared by diluting 5.0 mL of 6.0 M HCl to 60.0 mL
Monday, October 13, 2014 at 7:33pm

Chemistry
How many moles of solid Mg(OH)2 should you add to 200mL of 0.15M lactic acid solution to produce pH 4.0 buffer?
Monday, October 13, 2014 at 6:39pm

Chemistry Equation
1) Write the equation for the reaction associated with the Ka2 of sulfuric acid, H2SO4. 2)Write the equation for the reaction associated with the Kb2 of carbonate, CO3^(2-).
Monday, October 13, 2014 at 6:36pm

chemistry pH
A 25 mL sample of 0.29 M LiOH analyte was titrated with 0.75 M HI at 25 degree Celsius. 1)Calculate the initial pH before any titrant was added. 2) Then calculate the pH of the solution after 5 mL of titrant was added.
Monday, October 13, 2014 at 6:34pm

chemistry
Equal volumes of 0.220 M weak base (Kb=4.0x10^-9) and 0.220 M HCl are mixed. Calculate the pH of the resulting solution
Monday, October 13, 2014 at 6:32pm

chemistry
Nitric acid, HNO3, was first prepared 1200 years ago by heating naturally occurring sodium nitrate (called saltpeter) with sulfuric acid to produce sodium bisulfate and collecting the vapors of HNO3 produced. Calculate ΔH°rxn for this reaction. ΔH°f[NaNO3(s...
Monday, October 13, 2014 at 6:16pm

Chemistry
For a tablet containing 500mg vitamin C, Calculate how many mL of 0.095M NaOH are required for titration ( molar mass of ascorbic acid- vitamin c is 1.76.12g/mol) I am not sure of the conversions to use, how to get started with the question.
Monday, October 13, 2014 at 5:53pm

chemistry
Are the characteristics or properties of the elements making up a compound different from the characteristics or properties of the compound? For example, are the properties of oxygen and hydrogen different from the properties of water? Explain.
Monday, October 13, 2014 at 5:20pm

College Chemistry lab
How do I Calculate the concentration of iron(lll) with absorbance measurement. Wavelength is 480nm, solution is 1 ml FeCl3 : 9ml HCl, absorption is .250A, concentration of stock FeCl3 solution is 0.00050M and stock HCl solution is 2.0M. I not sure how to use beer's law to ...
Monday, October 13, 2014 at 4:20pm

chemistry
Nitric acid, HNO3, was first prepared 1200 years ago by heating naturally occurring sodium nitrate (called saltpeter) with sulfuric acid to produce sodium bisulfate and collecting the vapors of HNO3 produced. Calculate ΔH°rxn for this reaction. ΔH°f[NaNO3(s...
Monday, October 13, 2014 at 3:09pm

Chemistry
Cambridge uses FA 1, FA 2 etc to name chemicals or solutions. What does FA stand for?
Monday, October 13, 2014 at 12:15pm

chemistry
A carbonate ion, CO32−, can participate in an acid-base reaction. How should the carbonate ion be classified?
Monday, October 13, 2014 at 12:11pm

chemistry/math
5.0 moles of solid sodium chloride (NaCl) are used to prepare a 5.0 M NaCl solution. What is the volume of the solution?
Monday, October 13, 2014 at 12:06pm

chemistry
How many moles of magnesium chloride are formed when 55 mL of 0.70 M HCl is added to 42 mL of 1.204 g Mg(OH)2? Mg(OH)2(s) + 2HCl(aq) MgCl2(aq) + 2H2O(l) A. 0.019 mol B. 0.012 mol C. 0.021 mol D. 0.039 mol
Monday, October 13, 2014 at 11:45am

Chemistry
Molecular, ionic, and net ionic equations for ammonium chloride + potassium sulfate. Also what is the observation. Is it 2NH2Cl + Na2SO4 = (NH4)2SO4 + 2NaCl???? Please help!
Monday, October 13, 2014 at 5:03am

Chemistry 101
A solution containing 83.100 g of sodium hydroxide [molar mass = 40.0 g/mol] was neutralised using phosphoric acid. Calculate the moles of sodium phosphate formed (assuming that the reaction goes to completion). Give your answer to three significant figures. I'm not sure ...
Monday, October 13, 2014 at 2:19am

chemistry
To resolve an object in an electron microscope, the wavelength of the electrons must be close to the diameter of the object. What kinetic energy must the electrons have in order to resolve a protein molecule that is 7.00 nm in diameter? Take the mass of an electron to be 9.11&...
Sunday, October 12, 2014 at 11:44pm

chemistry
A beaker contain 300.ml of a 0,20 M Pb(NO3) solution. If 200 ml of 0,20M solution og MgCl2 is added to the beaker, What will be the concentration of Pb2+ ions in the resulting solution
Sunday, October 12, 2014 at 11:22pm

chemistry
An unknown diprotic acid requires 26.66 mL of 0.117 M NaOH to completely neutralize a 0.845 g sample. what is the molar mass of the acid?
Sunday, October 12, 2014 at 10:03pm

Organic Chemistry
Aqueous sodium bicarbonate was used to wash the crude t-pently chloride. What was the purpose of the wash? give equations.
Sunday, October 12, 2014 at 8:12pm

chemistry
A student weighs out 0.568 g of KHP (molar mass = 204 g/mol) and titrates to the equivalence point with 36.78 mL of a stock NaOH solution. What is the concentration of the stock NaOH solution? KHP is an acid with one acidic proton. a. 3.15 M b. 0.0757 M c. 0.943 M d. 0.100 M ...
Sunday, October 12, 2014 at 7:10pm

chemistry
5.00g aluminum sulfide and 10.0g water react according to the reaction: Al2S3 + 6 H2O -> 2 Al(OH)3 + 3 H2S What is maximum mass of H2S that can be formed? What mass of excess reactant remains when the reaction is complete?
Sunday, October 12, 2014 at 5:31pm

chemistry
What weight of lead nitrate in grams would need to be dissolved in 400 mL of water to prepare a 270 ppm solution of Pb2+?
Sunday, October 12, 2014 at 5:24pm

Chemistry
It is easy but I cannot solve or do buffer questions/slns.. Please help. Describe the preparation of 500 ml of 1 M phosphate buffer at pH 7.2.
Sunday, October 12, 2014 at 3:59pm

Chemistry
Orbital Hybridization of CH2Cl2?
Sunday, October 12, 2014 at 3:39pm

CHEMISTRY
If precipitation of BaSO4 is incomplete due to inadequate heating or insufficient time what will happen to the sulfate percent error determination? And why?
Sunday, October 12, 2014 at 3:31pm

Chemistry
If the density of ocean water at depth of 10,000m is 1.071g/ml and if 25.0g of water at that depth contains 190mg of KCl what is the molarity of KCL?
Sunday, October 12, 2014 at 3:01pm

chemistry
An analytical procedure requires a solution of chloride ions ,How many grams of CaCl2 must be disolved to make2.15L of 0.0520 M C
Sunday, October 12, 2014 at 3:00pm

Chemistry
If you wanted to make a barometer that had a column of liquid about 6ft tall what would the density of the liquid have to be? 1meter=3.28ft 1in=2.54cm Density Hg=13.6g/ml 1atm=760torr
Sunday, October 12, 2014 at 2:42pm

chemistry
An experiment to determine compound partition among air, water, and soil phases was conducted by adding 1 gram of the compound to a reactor that had 1 m3 of air, 0,001 m3 of water0 and 100 g of solid. The reactor was at atmodpheric pressure and at aconstant tepmrature 20 C The...
Sunday, October 12, 2014 at 2:12pm

chemistry
You mix 50.0 ml of 2.0 M HCl and 50.0 ml of 2.0M NaOH. The temperature of the resulting solution increases from 22.5 degrees celcius to 32.3 degrees celcius. What is the q of the calorimeter
Sunday, October 12, 2014 at 2:02pm

chemistry
a saturated solution of potassium chloride prepared at 60degree celsius is allowed to cool at room remperature
Sunday, October 12, 2014 at 11:43am

Chemistry
How many grams of C are there in a sample of C that contains the same number of moles as a 25.4 gram sample of Ca?
Sunday, October 12, 2014 at 10:14am

Chemistry
The mass of an electron is 9.11× 10–31 kg. What is the uncertainty in the position of an electron moving at 5.00 × 106 m/s with an uncertainty of Δv = 0.01 × 106 m/s?
Sunday, October 12, 2014 at 9:23am

CHEMISTRY
how to calculate the weight of solute req'd to prepare 1 liter of 1 normal of: a.) LiOH b.) phosphoric acid my work: formula= gew/L or w/ewxL i get their mw then divide it to their H/OH so i can get EW then multiply it to 1. a.) 24 g/mol/1 b.) 98g/mol/3 i dont know what&#...
Sunday, October 12, 2014 at 5:55am

CHEMISTRY
How many mL of pure isopropyl alcohol is needed to prepare 250 mL of 70% isopropyl alcohol (C3H7OH). I'm thinking if i should use vol of solute/vol of sol'n but it doesn't fit the formula and im confuse it. please help me
Sunday, October 12, 2014 at 5:49am

CHEMISTRY HELP
Calculate boiling point and freezing point of this solution which contains 5.85g of C6H12O6 in 255g H2O. pleasee
Sunday, October 12, 2014 at 5:06am

Chemistry
A precipitate forms when solutions of sodium carbonate and calcium nitrate are combined. Write the net ionic equation for this reaction. Please help
Sunday, October 12, 2014 at 4:18am

chemistry
If you wanted to make a barometer that had a column of liquid about 6 feet tall, what would the density of the liquid have to be? 1 meter = 3.28 ft 1 inch = 2.54 cm Density Hg = 13.6 g/mL 1atm = 760 torr
Sunday, October 12, 2014 at 3:40am

CHEMISTRY
Calculate boiling point and freezing point of this solution which contains 5.85g of C6H12O6 in 255g H2O. pleasee
Sunday, October 12, 2014 at 3:03am

chemistry
0.6905kg zinc reacts with hydrochloric acid.how many balloons can be filled with the hydrogen gas where the pressure inside the balloon is 790metrehg and temperature is 27 degree centigrade .
Sunday, October 12, 2014 at 2:32am

chemistry
Calculate the concentration of iron(III) in 2.0 M of 9 ml HCL and 0.00050 M of 1 ml FeCl3? Please help me :(
Sunday, October 12, 2014 at 1:50am

Chemistry
What is the mechanism of an aldehyde reacting with fehlings solution and tollens reagent? I know it is oxidised to a carboxylic acid, but i want to know the mechanism. Thank you.
Sunday, October 12, 2014 at 1:17am

chemistry
A 300mL solution was made by dissolving 5.0g of MgCl2 in water. What is its molarity?
Saturday, October 11, 2014 at 11:50pm

CHEMISTRY
how many grams of glucose, C6H12O6 and water are in 600g of 5.5% by mass glucose solution? please indicate the general formula to use to solve this problem.
Saturday, October 11, 2014 at 11:47pm

Chemistry
My lab had done protein crystallography with lysozyme. Two solutions were used to prepare the crystallization: lysosome solution and the precipitate solution. 1) There was a distinct amount of starting material in a well. what would that do to the size of the crystals if the ...
Saturday, October 11, 2014 at 11:18pm

CHemistry
write the balanced net ionic equation that shows the formation of Fe(OH)3 in the reaction of iron (III) nitrate with sodium hydroxide. Please help
Saturday, October 11, 2014 at 10:04pm

Chemistry
Calculate the fourth ionization energy of beryllium in J atom^-1 & kJ mol^-1 units
Saturday, October 11, 2014 at 10:04pm

Chemistry
a 175.0 ml solution is made up of 20.0g of titanium(iii) chloride and H2O. What is it's molarity? I am just trying to check my work. M= 0.1296/0.175 =0.740
Saturday, October 11, 2014 at 9:41pm

Chemistry
Assume that you start with 2 mole(s) of magnesium metal, determine: The number of grams of MgO(s) that would be produced in the following reaction (enter your answer with 4 significant figures): Mg(s) + 1/2O2(g) → MgO(s)
Saturday, October 11, 2014 at 9:34pm

Chemistry
Write the balanced molecular equation for the reaction between lithium phosphate and calcium nitrate.
Saturday, October 11, 2014 at 9:26pm

chemistry
An alternative approach to bomb calorimetry is toestablish the heat capacity of the calorimeter, exclusive of the water it contains. The heat absorbed by the water and by the rest of the calorimeter must be calculated separately and then added together. A 1.148g sample of ...
Saturday, October 11, 2014 at 7:04pm

Chemistry
How much heat would you need to melt 20.0 L of ice that had frozen on a fruit tree.
Saturday, October 11, 2014 at 4:03pm

AP Chemistry
1. If alum is heated at first too strongly causing it to splatter out of the crucible what effect will this have on the determination of the water hydration? 2. If alum is heated insufficiently what effect will this have on the determination of the water hydration? 3. If not ...
Saturday, October 11, 2014 at 3:33pm

CHEMISTRY
Write a balanced chemical equation for the reaction of solid vanadium(V)({\rm V}) oxide with hydrogen gas to form solid vanadium(III)({\rm III}) oxide and liquid water.
Saturday, October 11, 2014 at 2:48pm

CHemistry
Assuming the final concentration of chloride anion after the addition of HCl (precipitation step) was 0.1M, what is the remaining concentration of Ag+ in the solution? (pKsp for AgCl = 9.74)
Saturday, October 11, 2014 at 2:20pm

chemistry
you have not added enough sodium hydroxide to precipitate all the copper as copper hydroxide. How could you tell that not all the copper had precipitated?
Saturday, October 11, 2014 at 2:04pm

chemistry
When a metal was exposed to light at a frequency of 3.86× 1015 s–1, electrons were emitted with a kinetic energy of 3.60× 10–19 J. What is the maximum number of electrons that could be ejected from this metal by a burst of light (at some other frequency) ...
Saturday, October 11, 2014 at 12:32pm

chemistry
how to do a research paper
Saturday, October 11, 2014 at 11:51am

chemistry
What is the percentage yield of the reaction of 4.9 g isoamyl alcohol with 4.9 g of acetic acid if 3.5 g of isoamyl acetate product is obtained after distillation? Enter your answer, without a % symbol, to 2 sig. figs.
Saturday, October 11, 2014 at 3:56am

Chemistry URGENT!!
Which anions have the largest and smallest radii? Thank you!!
Friday, October 10, 2014 at 10:07pm

Chemistry
Which positive ion (cation) has the smallest radius? Please help! Thanks!
Friday, October 10, 2014 at 9:25pm

Chemistry
If 43.2 mL of 2.46 M HClO4 solution completely reacts with a 75.0 mL sample of a sodium hydroxide solution, what is the molarity of the sodium hydroxide solution? (hint: write the complete balanced rxn)
Friday, October 10, 2014 at 9:17pm

chemistry
a solution is made by mixing 38.0 ml of ethanol C2H6O, 62.0mL of water. assuming ideal behavior, what is the vapor pressure of the solution at 20 C
Friday, October 10, 2014 at 9:08pm

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