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October 20, 2014

Homework Help: Science: Chemistry

Recent Homework Questions About Chemistry

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Chemistry
Round this to two sig figs: 4025000 Is the correct answer 4.0 x 10^6?
Wednesday, September 26, 2012 at 8:48pm

Chemistry
Convert 3.01 x 10^23 atoms of silicon to moles of silicon. on my paper i have the equations moles S = 3.01 x 10^23 atoms x 1 mole/6.022x10^23 atoms but i'm not sure how to do this. help?
Wednesday, September 26, 2012 at 7:39pm

chemistry
how do you name halogens as a functional group. like CH3-Cl
Wednesday, September 26, 2012 at 6:31pm

Chemistry
How would I calculate the mass of 20ml of a 3% hydrogen peroxide from a 30% H2O2 solution?
Wednesday, September 26, 2012 at 5:39pm

Chemistry
I Posted this question the other day: A 1.00 g 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 1.00 L solution ...
Wednesday, September 26, 2012 at 5:34pm

Chemistry
Lab: Titration of NaOH (0.1 molar)to unknown solid acid. Trying to determine the equilivent weight of the unknown acid in the experiement. I am trying to figure out if I add too much base solution by accident to an unknown acid during titration would it affect the equivalent ...
Wednesday, September 26, 2012 at 5:28pm

chemistry
about how many bacteria (e coli) would you have to line up to stretch 1mm??
Wednesday, September 26, 2012 at 5:27pm

chemistry
a typical E coli is 2um in length, how long is the E coli in nanometers??
Wednesday, September 26, 2012 at 5:26pm

chemistry
which temperature is colder: 50F or 50C???
Wednesday, September 26, 2012 at 5:22pm

chemistry. urgent!
where woudl i put the propyl in 2-propyl benzoate? i thought the propyl had to be attactched to the O and wouldnt that just be 1-propyl not 2?
Wednesday, September 26, 2012 at 4:44pm

general chemistry 2
How many grams of urea [CO(NH2)2] would be required to prepare 200 mL of a 5.0 x 10-3 molar solution? Answer
Wednesday, September 26, 2012 at 3:46pm

Chemistry
What is the temperature change in celsius when 29.5L of water absorbs 2.3 kwh of heat?
Wednesday, September 26, 2012 at 3:33pm

Chemistry
What volume of 0.200M of aqueous solution of formic acid, a weak monoprotic acid (KA = 1.78x10-4) and 0.200M aqueous solution of NaOH would you mix to prepare a 500mL of a buffer solution of pH = 4.0. I know I need to use the H-H equation, I'm just not sure what I plug in ...
Wednesday, September 26, 2012 at 2:31pm

chemistry
The half-life for the radioactive decay of calcium-47 is 4.5 days.If a sample has an activity of 4.00uCi after 13.5 days, what was the initial activity of the sample?
Wednesday, September 26, 2012 at 2:30pm

chemistry
Technetium-99m is an ideal radioisotope for scanning organs because it has a half-life of 6.0 {\rm hr} and is a pure gamma emitter. Suppose that 280{\rm mg} were prepared in the technetium generator this morning. How many milligrams would remain after the following intervals?
Wednesday, September 26, 2012 at 1:16pm

chemistry
KCl(s) → K+(aq) + Cl‾ (aq) Solid KCl dissolves as shown in the above equation. A 6.60 g sample of KCl was dissolved in 42.3 g of water. The initial temperature of the water was 21.90°C. After the compound dissolved, the temperature of the water was 10.20°C...
Wednesday, September 26, 2012 at 1:06pm

chemistry
Iodine-131, a beta emitter, has a half-life of 8 days.How many grams of a 10.0g sample of iodine-131 would remain after 56.0 days?
Wednesday, September 26, 2012 at 12:40pm

Chemistry
What is the net ionic equation of reaction of MgCl2 with NaOH? I got the equation and then balanced it and then omitted the spectator ions and ended up with: Mg(OH)2(aq)--->Mg(OH) (s) I wanted to confirm to see if that was correct, thanks.
Wednesday, September 26, 2012 at 12:11pm

Chemistry
a solid mixture is 3.00 grams and 65.0% NiCO3. How much nickel carbonate was lost if the sample was dissolved in 20.0 mL of water and washed with an additional 50.0 mL of water? I just don't know how to set up the problem..I don't need it solved, just set up :)
Wednesday, September 26, 2012 at 12:07pm

Chemistry
A student reacted 5.33 grams of cobalt with oxygen gas and obtained 7.50 grams of cobalt oxide. Determine the empirical formula of this cobalt-oxygen compound based upon this experiment.
Wednesday, September 26, 2012 at 11:37am

chemistry
calculate the volume in milliliters of a 5.55g sample of solid with density of 3.67g/ml
Wednesday, September 26, 2012 at 11:32am

Chemistry
What volume of 0.200M of aqueous solution of formic acid, a weak monoprotic acid (KA = 1.78x10-4) and 0.200M aqueous solution of NaOH would you mix to prepare a 500mL of a buffer solution of pH = 4.0.
Wednesday, September 26, 2012 at 11:13am

chemistry
When californium-249 is bombarded by oxygen-18, a new isotope and four neutrons are produced. Express your answer as a nuclear equation.
Wednesday, September 26, 2012 at 10:23am

chemistry
Radon-222 undergoes alpha decay.what is the nuclear equation
Wednesday, September 26, 2012 at 10:13am

chemistry
why should we add 273 to convert a given celcius value in to kelvin?
Wednesday, September 26, 2012 at 10:04am

chemistry
Technetium-99m is an ideal radioisotope for scanning organs because it has a half-life of 6.0 {\rm hr} and is a pure gamma emitter. Suppose that 280{\rm mg} were prepared in the technetium generator this morning. How many milligrams would remain after the following intervals?
Wednesday, September 26, 2012 at 10:04am

Chemistry
How to do significant values in Chemistry? I am totally stuck; I have no idea what to do? My teacher gave me C due to the significant value error. Please help
Wednesday, September 26, 2012 at 9:28am

Chemistry
A student dried a wet crucible with a kimwipe. A piece of kimwipe was left clinging to the inside wall of the crucible. The student did not see the piece of kimwipe when adding the NaHCO3-KCl mixture to the crucible. The crucible and its contents were weighed and subjected to ...
Wednesday, September 26, 2012 at 1:34am

chemistry
Prepare 1.5 liters of 0.25 M Tris buffer, pH 7.5. Useful information: pKa Tris = 8.1 Formula weight of Tris (hydroxymethyl aminomethane) base = 121.1 Formula weight of Tris hydrochloride (acid form) = 158.0
Wednesday, September 26, 2012 at 1:05am

Chemistry
The density of platinum is 23.4 g/cm cubed. Calculate the mass of 75.0cm cubed of platinum.
Tuesday, September 25, 2012 at 11:40pm

Chemistry
When 0.312g of glucose was burned in a bomb calorimeter (heat capacity 641 J/K) the temperature rose by 7.739 K. Calculate the standard enthalpy of combustion and the standard internal energy of combustion. I've calculated the standard enthalpy but am unsure of how to go ...
Tuesday, September 25, 2012 at 11:39pm

chemistry
A student wishes to prepare 1.000 g of silver chromate. How many mL of .05000M silver nitrate solution should be added to 50.00 mL of .0700M potassium chromate solution assuming 100% yield
Tuesday, September 25, 2012 at 11:24pm

chemistry
10HI+2KMNO4+3H2SO4-5I2+2MNSO4+K2SO4+8H20​ Find the mass of water produced when 300g HI reacts with 30 g KMno4 and excess H2So4. Find the mass of k2So4 produces 30 mL of .250 M KMno4 reacts with 400 mL .100 M HI.
Tuesday, September 25, 2012 at 10:54pm

Chemistry
if you double the concentration of HCL acid, will that double rate of reaction? i have to explain in terms of the theory of collision. Wont doubling the concentration double the rate as well?
Tuesday, September 25, 2012 at 10:38pm

Chemistry
When hydrochloric acid (HCl) is added to water it dissociates to form H3O+ (aq) and Cl− (aq) as shown below. HCl (aq) + H2O (l) → H3O+ (aq) + Cl− (aq) What happened to the electrons in the H-Cl bond? Choose the best answer. The electrons are transferred to ...
Tuesday, September 25, 2012 at 10:32pm

Chemistry
When a clear aqueous solution of calcium chloride (CaCl2) is mixed with a clear aqueous solution of sodium carbonate (Na2CO3), a white solid precipitate forms. What happens to the mass of the mixture after the solid precipitate forms? Choose the best answer. Mass decreases ...
Tuesday, September 25, 2012 at 10:31pm

Chemistry - ASAP please!
what is the hybridisation state of the oxygen of a carbonyl group
Tuesday, September 25, 2012 at 9:22pm

Chemistry
out of these conditions, which would result in fastest reaction? a. 2.0M HCL, powedered CaCO3 chip, 50 degrees celsius b. 6.0M HCL, CaCO3 chip, 25 degrees celsius c. 6.0M HCL, powdered CaCO3, 50 degrees celsius. d. 2.0M HCL, CaCO3 chip, 50 degrees celsius. Im guessing C ...
Tuesday, September 25, 2012 at 8:53pm

chemistry
what is the minimum temperature needed to dissolve 60 grams of K2CR2O7 in 100 milliliters of water?
Tuesday, September 25, 2012 at 8:26pm

chemistry
what is the minimum temperature needed to dissolve 60 grams of K2CR2O7 in 100 milliliters of water?
Tuesday, September 25, 2012 at 8:23pm

chemistry
Which of the following elements is synthetic? uranium iodine helium nobelium
Tuesday, September 25, 2012 at 8:21pm

chemistry
How many electrons are in the outermost principal energy level of an atom of nitrogen in the ground state?
Tuesday, September 25, 2012 at 8:18pm

chemistry
-What volume of .500 M Pb(NO3)2 is required to react completely with 18.25 L of .625 M Na2SO4?
Tuesday, September 25, 2012 at 8:12pm

chemistry
-What volume of .500 M Pb(NO3)2 is required to react completely with 18.25 L of .625 M Na2SO4?
Tuesday, September 25, 2012 at 8:10pm

Chemistry
What is the hybridization of phosphorous in a P4 molecule
Tuesday, September 25, 2012 at 6:57pm

AP Chemistry
If a breath of air has a volume of 1.02L at a pressure of 750 Torr and 37°C, calculate the number of molecules of air in the breath.
Tuesday, September 25, 2012 at 6:38pm

Chemistry
For the reaction below, when 216g of ICl3 reacts with 61.3g of H2O: 2ICl3 + 3H2O -> ICl + HIO3 + 5HCl a)which is the limiting reagent? b)how many grams of HIO3 are formed? c)how many grams of the nonlimiting reagent are left over?
Tuesday, September 25, 2012 at 6:15pm

chemistry
Water has a density of 0.089 g/ml. What is the volume, in gallons, of 11.1 tons of water?
Tuesday, September 25, 2012 at 6:13pm

College Chemistry
How many grams of H3BO3 forms when 28.16 grams B2H6 react with excess water?
Tuesday, September 25, 2012 at 5:16pm

chemistry
Give the number of each type of ion present in each of the ionic compounds formed from the combination of the indicated metal and acetate, {\rm C_2H_3O_2}^-, ion.
Tuesday, September 25, 2012 at 5:02pm

Ap Chemistry
Re has two natural occuring isotopes 185 Re and 187 Re with an average atomic mass of 186.207 amu. Re is 62.60% 187Re and the atomic mass of 187Re is 186.956 amu. What is the mass of 185 Re
Tuesday, September 25, 2012 at 4:54pm

Chemistry
Would Ti3(PO4)2 be titanium phosPHATE or phosPHIDE
Tuesday, September 25, 2012 at 4:47pm

chemistry
first task is to prepare 250 ml of 3 M glucose. Then You are preparing a solution and the recipe calls for 25 ml of 10% glucose. How much of the 3M glucose stock would you need to add to so that you are adding the same molar amount of glucose?
Tuesday, September 25, 2012 at 4:41pm

Chemistry
How can you calculate activation energy in (kj/mol)? When all that is given is inverse temperature, and natural log reaction constant? Inverse: 1/278 for Kelvin temp, 1/308 Natural Log Reaction Rate Constant: 4.3 5.5
Tuesday, September 25, 2012 at 4:33pm

Chemistry
How do you do the inverse of absolute temperature? My kelvin temperatures are: 298 308 318 328 338 348 358 368 378 Taking the natural log of both sides of both sides of the equation gives ln(k) = ln(A) – E/RT. Thus, a graph of the natural log of the reaction rate constant...
Tuesday, September 25, 2012 at 4:24pm

chemistry
Prepare 150 ml of a reaction buffer containing 0.75% MgCl2, 35mM glucose, 750 nM ATP, and 20 mM Tris-Cl, pH 7.5. In addition, you have a 20% MgCl2 stock solution and the lab freezer has 10 mM ATP that you can dilute to the correct concentration.
Tuesday, September 25, 2012 at 4:11pm

chemistry
How would you prepare 500 ml of a 1.8 M phosphate buffer (pH 6.8) containing 4.5 x 10-6 M CaCl2 and 52 mM sucrose?
Tuesday, September 25, 2012 at 4:09pm

Chemistry
Mg +2HCL = MgCl2 +H2 what mass of hydrogen is obtained by adding excess hydrochloric acid to 6g of magnesium
Tuesday, September 25, 2012 at 3:46pm

Chemistry
Would Ca(HCO3)2 be calcium hydrogen carbonate?
Tuesday, September 25, 2012 at 3:25pm

Chemistry
How to prepare a 750mL stock solution with a 0.40 M Na2S2O3.
Tuesday, September 25, 2012 at 2:50pm

chemistry
What is the valency and outer most electrons in scandium to zinc?
Tuesday, September 25, 2012 at 10:48am

chemistry
I'am unable to identify which is upper meniscus and lower meniscus while taking a solution in burette.please tell me how to identify it easily.
Tuesday, September 25, 2012 at 10:44am

chemistry
Slater rules for calculeting sigma and Zeff
Tuesday, September 25, 2012 at 2:42am

Chemistry
Ok so reviewing my notes I also got 11,326.6 as the volume in ml. The density of water he wanted us to use was (0.9975) and I went from 1 gal of H2O = 3.785 liters = 3785 grams then multiplied by 3 giving me 11,355g H2O. The only other step I could come up with was using the ...
Tuesday, September 25, 2012 at 1:21am

Chemistry
how many moles of Cl in 2.7 mol CaCl2
Tuesday, September 25, 2012 at 12:37am

Chemistry
I've got a similar question as a previous student. What is a minimum volume (in gallons) of ethylene glycol (CH2OHCH2OH, an antifreeze) that has to be added to 3.00 gal of water if you desire this engine cooling solution (for a auto radiator) NOT to be frozen below - 25.9 ...
Tuesday, September 25, 2012 at 12:30am

chemistry
How many grams of Kl are required to prepare 500 mL of 0.04 M Kl?
Tuesday, September 25, 2012 at 12:10am

chemistry
The following is kinetic rate data taken as absorbance of reactant vs. time: A: ln(A): Time/min: 0.532 ?? 0.0 0.484 2.54 0.442 5.12 0.395 8.35 0.350 11.95 fill in the ln(A) column
Monday, September 24, 2012 at 11:15pm

chemistry
a 225.0 gram sample of aluminum is heated and the temperature increased from 50.0 celsius to 65.0 celsius for temperature change of 15.0 celsius. how many calories of heat was absorbed to produce this temperature change?
Monday, September 24, 2012 at 10:49pm

Chemistry
A 2.914 gram sample of gypsum, a hydrated salt of calcium sulfat, CaSO4, is heated at a temperature greater than 170 degrees Celcius in a crucible until a constant mass is reached. The mass of the anhydrous CaSO4 salt is 2.304 grams. Calculate the percent by mass of water in ...
Monday, September 24, 2012 at 10:47pm

chemistry.
a quantity of 25 ml of a solution containing both Fe2+ and Fe3+ ions is titrated with 23 ml of .02 M KMnO4 solution. as a result all the Fe2+ ions are oxidised to Fe3+ ions. Next the solution is treated with Zn metal to convert all Fe3+ ions to Fe2+ ions. Finally, the solution...
Monday, September 24, 2012 at 10:21pm

chemistry
convert the following measurements to the units specified 1) 357ml = ?L 2) 25kg = ?mg 3) 35,000cm = ?L
Monday, September 24, 2012 at 10:18pm

chemistry
Copper (II) fluoride contains 37.42% {\rm F} by mass. Use this percentage to calculate the mass of fluorine (in {\rm g}) contained in 56.0{\rm g} of copper (II) fluoride
Monday, September 24, 2012 at 10:10pm

chemistry
convert the following measurements to the units specified 1) 357ml = ?L 2) 25kg = ?mg 3) 35,000cm = ?L
Monday, September 24, 2012 at 9:50pm

Chemistry
Why is my actual percent of sulfate in alum a lot less than my theoretical percent of sulfate in alum? Actual Percent SO4= 1.68% Theoretical Percent SO4= 40.5%
Monday, September 24, 2012 at 9:50pm

Chemistry
When carbon is burned in air, it reacts with oxygen to form carbon dioxide. When 25.2 of carbon were burned in the presence of 80.6 of oxygen, 13.4 of oxygen remained unreacted. What mass of carbon dioxide was produced?
Monday, September 24, 2012 at 8:16pm

chemistry
A sample of sodium reacts completely with 0.568 of chlorine, forming 936 of sodium chloride. What mass of sodium reacted?
Monday, September 24, 2012 at 8:15pm

chemistry
large and small number are most easily handle when expressed in
Monday, September 24, 2012 at 8:00pm

chemistry
What happens if you attempt to recover CaCO3 by adding 3M H2SO4 instead of 3M HCI to a Si)2/CaCO3 residue?
Monday, September 24, 2012 at 7:34pm

Chemistry
At 298K and 1bar pressure, the density of water is 1.00 g/cm^3 , Cpm = and 75.3 J/Kmol. The change in volume with temperature is given by delta V = ViB(deltaT), where B, the coefficient of thermal expansion, is 2.07 * 10^-4 K^-1. If the temperature of 350g of water is ...
Monday, September 24, 2012 at 6:23pm

Chemistry
Calculate the molarity of a 100. mL solution containing 22.3 g of sucrose (C12H22O11)
Monday, September 24, 2012 at 5:50pm

chemistry
The safe level of radon gas at home is 4X10e-12 Ci/L or less. If you measure radon levels in the basement what is the maximum number of Ci that could be safe to find in a basement with dimensions of 12 ft x 15 ft x 6 ft?
Monday, September 24, 2012 at 5:33pm

Chemistry
1. What is the minimum volume of hot water needed to dissolve 0.200g phenacetin? How much phenacetin will remain in that volume of water once it cools? 2. Why is it important that all the solid dissolves in the hot solvent, before the solution is cooled? 3. How would you ...
Monday, September 24, 2012 at 5:00pm

General Chemistry
Which chemical reactions would you consider to be of importance to a healthcare professional and why?
Monday, September 24, 2012 at 4:51pm

chemistry
It takes 1 hour and 17 min. for a 1.000g sample of a certain isotope to decay to 0.121g. What is the half-life of this isotope? plssss helpp
Monday, September 24, 2012 at 4:42pm

Chemistry
Find the thetrical formula for .012 mol of H20, .0056 moles of Cl2 and .0060 of copper with a formula like this CuCl*H20 *=point in center
Monday, September 24, 2012 at 3:48pm

chemistry
which element is liquid @ 25.0c and 1 atmosphere pressure?
Monday, September 24, 2012 at 3:35pm

chemistry
if you are exposed to all sources of radiation from natural sources and human activities (worldwide average). How many years would it take for you to absorb a fatal dose of radiation plss help
Monday, September 24, 2012 at 2:41pm

Chemistry
What does it mean if the percent of sulfate in a sample of alum is greater that the theoretical percent of sulfate in alum?
Monday, September 24, 2012 at 2:16pm

Science chemistry
It takes 1 hour and 17 min. for a 1.000gsample of a certain isotope to decay to 0.121g. What is the half-life of this isotope? plssss helpp
Monday, September 24, 2012 at 1:22pm

Chemistry
For the unbalanced reaction: FeSO4 (s) → Fe 2O3 (s) + SO2 (g) + O2 (g) ; how many total moles of gas are produced from the decomposition of 9.98 mol FeSO4 (s)?
Monday, September 24, 2012 at 1:06pm

Chemistry
What is the reactant when sugar is mixed with water? Also, what is the product?
Monday, September 24, 2012 at 12:52pm

chemistry, i need help like a.s.a.p!!!!
What is the density of a block of unknown material with a mass of 19.07 g if the dimensions are: length = 3.1 cm height = 1.9 cm width = 4.6 cm
Monday, September 24, 2012 at 11:41am

chemistry, i need helppp like a.s.a.p!!!!
What is the density of a 23.92 g object block if the dimensions: length = 10.6 mm height = 5.47 cm width = 0.0352 m
Monday, September 24, 2012 at 11:40am

chemistry
how to balance a complicated chemical equation.explain with a example.tell me a shortcut to balance complicated chemical equation.
Monday, September 24, 2012 at 10:52am

chemistry
How long would it take to melt a 400 lb.block of ive at a temperature of 55 degrees
Monday, September 24, 2012 at 10:41am

Chemistry
Carbon-14 has a half-life of 5730 years In a plant fossil you find that the 14 C has decayed to 1/8 of the original amount how long ago was this plant
Monday, September 24, 2012 at 10:09am

chemistry
Need to write a brief description of the procedure required to make 900mL of a 0.5 M NaCl solution. The formula weight of NaCl is 58.4g/mole.
Monday, September 24, 2012 at 2:27am

chemistry
how many grams of NaOH should be used to make 200 mL of a 0.24M solution of NaOH starting with a .4M HCL solution
Monday, September 24, 2012 at 1:48am

chemistry
What is the density of a block of unknown material with a mass of 19.07 g if the dimensions are: length = 3.1 cm height = 1.9 cm width = 4.6 cm
Monday, September 24, 2012 at 1:22am

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