Monday
December 5, 2016

Homework Help: Science: Chemistry

Recent Homework Questions About Chemistry

chemistry
If the heat of combustion for a specific compound is -1180.0 kJ/mol and its molar mass is 40.91 g/mol, how many grams of this compound must you burn to release 114.50 kJ of heat?
Friday, October 28, 2016 by anon

chemistry
A 2.50-g sample of powdered zinc is added to 100.0 mL of a 2.00-M aqueous solution of hydrobromic acid in a calorimeter. The total heat capacity of the calorimeter and solution is 448 J/K. The observed increase in temperature is 21.1 K at a constant pressure of one bar. Using ...
Friday, October 28, 2016 by anon

chemistry
When a 8.00-g sample of KBr is dissolved in water in a calorimeter that has a total heat capacity of 3.344 kJ·K–1, the temperature decreases by 0.400 K. Calculate the molar heat of solution of KBr.
Friday, October 28, 2016 by anon

chemistry
A researcher studying the nutritional value of a new candy places a 4.10-gram sample of the candy inside a bomb calorimeter and combusts it in excess oxygen. The observed temperature increase is 2.47 °C. If the heat capacity of the calorimeter is 33.90 kJ·K–1, ...
Friday, October 28, 2016 by anon

chemistry
At constant volume, the heat of combustion of a particular compound is –3947.0 kJ/mol. When 1.311 g of this compound (molar mass = 136.58 g/mol) was burned in a bomb calorimeter, the temperature of the calorimeter (including its contents) rose by 4.343 °C. What is the...
Friday, October 28, 2016 by anon

chemistry
Liquid sodium is being considered as an engine coolant. How many grams of liquid sodium (minimum) are needed to absorb 7.00 MJ of energy (in the form of heat) if the temperature of the sodium is not to increase by more than 10.0 °C? Use CP= 30.8 J/(K·mol) for Na(l) ...
Friday, October 28, 2016 by anon

chemistry
When 1367 J of heat energy is added to 44.1 g of hexane, C6H14, the temperature increases by 13.7 °C. Calculate the molar heat capacity of C6H14.
Friday, October 28, 2016 by anon

chemistry
An 80.0-gram sample of a gas was heated from 25 °C to 225 °C. During this process, 346 J of work was done by the system and its internal energy increased by 8305 J. What is the specific heat of the gas?
Friday, October 28, 2016 by anon

chemistry
If you combine 360.0 mL of water at 25.00 °C and 120.0 mL of water at 95.00 °C, what is the final temperature of the mixture? Use 1.00 g/mL as the density of water.
Friday, October 28, 2016 by anon

Chemistry
A solution of concentrated NaOH is 16.7M. If the density of the solution is 1.02 g/mL, what is the percent by mass of NaOH? I have tried different calculations and molarity and % but im not catching on at all
Friday, October 28, 2016 by Anonymous

Chemistry
A solution of concentrated NaOH is 16.7M. If the density of the solution is 1.02 g/mL, what is the percent by mass of NaOH? I have tried different calculations and molarity and % but im not catching on at all
Friday, October 28, 2016 by Anonymous

organic chemistry
inversion of S configuration to R configuration?????
Friday, October 28, 2016 by Anonymous

Chemistry
Please write down the redox reactions (using the half-reaction method!) a)Cl2 from OCl- and Cl- in acidic solution b)Br2 from BrO3- and Br- in acidic solution -You don't have to do both, but could you help me step up the half reactions especially for OCl- --> Cl2
Friday, October 28, 2016 by Annie

chemistry
An 80.0-gram sample of a gas was heated from 25 °C to 225 °C. During this process, 346 J of work was done by the system and its internal energy increased by 8305 J. What is the specific heat of the gas?
Thursday, October 27, 2016 by sam

Chemistry
How much sulphuric acid containing 90% H2SO4 by wt. is needed for the production of 1000 kg of HCl containing 42% HCl by weight in this reaction. 2NaCl + H2SO4 -----> Na2SO4 + 2HCl
Thursday, October 27, 2016 by Kritim

chemistry
Liquid sodium is being considered as an engine coolant. How many grams of liquid sodium (minimum) are needed to absorb 7.00 MJ of energy (in the form of heat) if the temperature of the sodium is not to increase by more than 10.0 °C? Use CP= 30.8 J/(K·mol) for Na(l) ...
Thursday, October 27, 2016 by sam

chemistry
When 1367 J of heat energy is added to 44.1 g of hexane, C6H14, the temperature increases by 13.7 °C. Calculate the molar heat capacity of C6H14.
Thursday, October 27, 2016 by sam

chemistry
In a constant-pressure calorimeter, 60.0 mL of 0.300 M Ba(OH)2 was added to 60.0 mL of 0.600 M HCl. The reaction caused the temperature of the solution to rise from 21.75 °C to 25.84 °C. If the solution has the same density and specific heat as water (1.00 g/mL and 4....
Thursday, October 27, 2016 by sam

Chemistry
Consider a mole of gas obeying the equation of state P⋅V = n⋅R⋅T + n⋅B(T)⋅P. Find w, q, ΔU, ΔS, ΔH, ΔA, and ΔG for a reversible isothermal expansion of this gas. Express your answers in terms of initial and final pressures...
Thursday, October 27, 2016 by Joesph

chemistry
An 80.0-gram sample of a gas was heated from 25 °C to 225 °C. During this process, 346 J of work was done by the system and its internal energy increased by 8305 J. What is the specific heat of the gas?
Thursday, October 27, 2016 by sam

chemistry
If you combine 360.0 mL of water at 25.00 °C and 120.0 mL of water at 95.00 °C, what is the final temperature of the mixture? Use 1.00 g/mL as the density of water.
Thursday, October 27, 2016 by sam

Chemistry
How many grams of H2O are required to react with excess CaC2 to produce 23.0 g of C2H2 according to the following equation? CaC2 + 2H2O -> Ca(OH)2 + C2H2 a.4.5 b.15.9 c.31.8 d.1.766 I think this equation works out by multiplying 2 moles by the molar mass of H2O. Please ...
Thursday, October 27, 2016 by Rebecca

Chemistry
If 3.60 moles of SiO2 and 3.60 moles of C react to form SiC accodring to the equation SiO2 + 3 C -> SiC + 2 CO how many moles of CO will be produced? a. 1.20 b.2.40 c.3.60 d.7.20 -Do I have to use SiC in any part of the equation, I am very confused and I think I just need ...
Thursday, October 27, 2016 by Rebecca

Chemistry
Methane, CH4 is the main component of natural gas which is used for cooking in many homes. The molar heat of combustion of methane is -890kj/mol. A cook wants to boil some water on a gas stove. If the stove burns 5.00g of methane to heat 2575 ml of water, what is the ...
Thursday, October 27, 2016 by Ray

Chemistry
My question talks about a buffer with HA and NaA, where NaA is the sodium salt of the acid. What does the equation for this look like? HA + NaA --> H+ + NaA2 ??
Thursday, October 27, 2016 by Dwayne

Chemistry
The principal quantum number (n): (1) specifies the subshell of the orbital. (2) specifies the principal shell of the orbital. (3) specifies the 3-D shape of the orbital. (4) specifies the maximum number of electrons. (5) none of the above
Thursday, October 27, 2016 by Beth

Organic Chemistry 1
Consider the HF solution with the concentration of 5%(w/v). You can convert the % concentration into the molarity. a) Assume that you have 100ml of this solution. Determine the number of moles of HF if the concentration of HF is given as 5%(w/v) For this part I did 5% is 5g ...
Thursday, October 27, 2016 by Zaza to DrBodd22

Organic Chemistry 2
The typical % yield for the reduction of 9-fluorenone using NaBH4 to obtain 9-fluorenol is 80%. In my experiment I obtained 89 %. Can you explain the reasons why my yield is higher? Is it better to obtain a higher yield or a lower yield than the expected one?
Thursday, October 27, 2016 by Alice

chemistry
A student determines the heat of dissolution of solid potassium perchlorate using a coffee-cup calorimeter of negligible heat capacity. When 2.13 g of KClO4(s) is dissolved in 106.00 g of water, the temperature of the solution drops from 25.00 to 23.17 °C. Based on the ...
Thursday, October 27, 2016 by ayesha

Chemistry
Draw the product(s) of the following reaction CH3-CH2-C(triple bond)C-CH2 ---------> ? (Na/NH3)
Thursday, October 27, 2016 by anon

Chemistry
Define electronegativity and then describe the trends in electronegativity within groups and across periods in the periodic table. Provide examples of the elements with the highest electronegativity value within a group and an example of an element with the highest energy ...
Thursday, October 27, 2016 by PLEASE HELP

Chemistry
A fictitious element X is composed of 78.0% of the isotope X-50, 15.0% of the isotope X-51 , and 7.0% of the isotope X-52. Estimate the atomic mass of element X. Show your work.
Thursday, October 27, 2016 by Gxlden

Chemistry
why are most elements on the periodic table found as compound in nature?
Thursday, October 27, 2016 by Briana

CHEMISTRY
WRITE A BALANCE EQUATION BETWEEN PHOSPHORIC ACID AND SODIUM HYDROXIDE USING METHYL ORANGE
Thursday, October 27, 2016 by QUEEN

Chemistry
How to find mmol? this is for dilantin by multistep synthesis lab. using 350 mg of benzoin = mmol? using 160 mg NH4NO3 = mmol?
Wednesday, October 26, 2016 by Denaiel

Chemistry
The solubility of KI in ethyl alcohol is 2.00 grams of KI in 100.0 grams of this alcohol. From this information, calculate the molarity of this solution.
Wednesday, October 26, 2016 by Anonymous

AP Chemistry
A typical bathtub can hold 94 gallons of water. Calculate the mass of natural gas that would need to be burned to heat the water for a tub of this size from 59 ◦F to 101 ◦F. Assume that the natural gas is pure methane (CH4) and that the products of combustion are ...
Wednesday, October 26, 2016 by David

Chemistry
A gallon of isopropanol (IPA) weighs 6,55 lbs. Since 1 lb=453.6 grams, calculate how many moles of ethanol (MM=60.1 grams per mole) are in a gallon of this substance.
Wednesday, October 26, 2016 by Anonymous

Chemistry
What is the standard concentration of FeSCN^2+ if 18mL of 0.200M Fe(NO3)3 were combined with 2mL of 0.0020M KSCN?
Wednesday, October 26, 2016 by Victoria

Chemistry
20cm3 of 0.1m sulphuric acid was required to react with 50.0cm3 of a solution of sodium hydroxide
Wednesday, October 26, 2016 by Aliyah

Chemistry
Standardization of iodine solution was prepared using 10.0 mL of a standard, 1.00 mg/mL, ascorbic acid solution. Titration with the iodine solution required 35.80 mL to reach the end point. What is the molarity of the iodine solution?
Wednesday, October 26, 2016 by Rachael

Chemistry
Homework question? Colmanite [Ca2B6O11 * 5 H20] is a salt whose boron content gives glass high clarity. You are a buyer for an optical fiber manufacturer and want pure material. You have just received a Certificate of Analysis for a lot that is 12.8 +- 1.2% (i.e;11.6 to 14.0...
Wednesday, October 26, 2016 by Timmy

Chemistry
Note- I do not want the answers. I just need to know how to set up each.. The combustion of isopropyl alcohol (Molar Mass=60.1 g/mole) is described by the following balanced equation: 1 C2H8O + 9 O2 (g) -> 6 CO2 (g) 8H2O (l) + 4012 kJ of heat energy a) How much heat energy ...
Wednesday, October 26, 2016 by Hanna

Chemistry
What is the mass of water produced when 5 moles of hydrogen burn in the presence of excess oxygen?
Wednesday, October 26, 2016 by Flaka

Chemistry
Some pieces of jewelry react with compounds in sweat. The reaction can leave stains on your skin. Not all jewelry has this effect. Use the activity series of metals to explain this observation. please help
Tuesday, October 25, 2016 by HolfBrincl

Chemistry
A certain mixture of helium, He, and krypton, Kr, has a mass of 10.0 g and occupies a volume of 20.0 L at 25.0EC and 1.20 atm. What is the mass of He in the mixture?
Tuesday, October 25, 2016 by john

Chemistry
describe the preparation of 12 mL of a 0.050 M solution of each of the halogens, using the reactions in the preceding question. Available to you are solid Ca(OCl)2; 0.20 M solutions of NaCl, NaBr, NaBrO3, and CuSO4; a 0.40 M solution of NaI; a 0.50 M solution of H2SO4; ...
Tuesday, October 25, 2016 by Jana

Chemistry
In a three reactions system the first two reactions are endothermic with DeltaH values of 138kj and 241kj. if the final reaction is exothermic what is the minimum value of DeltaH3 that would make the overall reaction exothermic? explain your reasoning. i beleive the minimum ...
Tuesday, October 25, 2016 by Anonymous

Chemistry
Silicon carbide (SiC) is made by reacting sand (Silicon dioxide, SiO2) with powdered carbon at high temperature. Carbon monoxide is also formed. What is the percent yield if 51.4kg of SiC is recovered from processing 100.0kg of sand? What mass (in kg) of carbon would be needed...
Tuesday, October 25, 2016 by Ray

chemistry
Calculate the molarity of 12.5g of sucrose (C12H22O11) in 80mL of solution. 12.01 x 12 = 144.12 1.01 x 22 = 22.22 16.00 x 11 = 176.00 ------------------- 342.34 12.5g ----- / 342.34 = 0.003/80 = 4.56 80mL
Tuesday, October 25, 2016 by kiki

chemistry
For each pair of compounds, predict which species will have the higher molar entropy at 298 K and 1 bar. Be sure to state your reasons for your choice. 1. N2(g) vs. F2(g) 2. ICl (g) vs. BrF(g) 3. 6Li(s) vs. 7Li(s
Tuesday, October 25, 2016 by Dylan

Chemistry
How to prepare 250ml of 2.5m solution of HCL
Tuesday, October 25, 2016 by Zoe

Chemistry
What is the solvent in70% of alchol solution?
Tuesday, October 25, 2016 by Ridwan darebo

chemistry
Calculate the mass of oxalic acid needed to prepare 150 ml of 0.442 M C2H2O4.
Tuesday, October 25, 2016 by Anonymous

Sciene ( Chemistry )
The heat of neutralisation of LiOH and HCL at 25 degree celsius is 34.868 kJ/mol.The heat of ionisation of LiOH will be ?
Tuesday, October 25, 2016 by Diksha

Chemistry
What is NaOH?
Tuesday, October 25, 2016 by Grace

chemistry
What is the wavelength of radiation whose frequency is 5.93 x 10^14 s-1
Tuesday, October 25, 2016 by E

Chemistry
A 250 g mass of material has a temperature of –45˚C. Its specific heat is 0.36 J/gˑ˚C. How much heat energy is required to raise its temperature to 10˚C? (its melting point is 23 ˚C)
Monday, October 24, 2016 by Leandra

Chemistry
Calculate the mass of water produced when 9.53 g of butane reacts with excess oxygen
Monday, October 24, 2016 by Anonymous

Ap chemistry
Calculate the concentrations of all ions present in the following solutions of strong electrolytes : 2.0 times 10-3 M AL2(SO4)3
Monday, October 24, 2016 by Tiffany

Chemistry pH, acids, and bases
Trichloroacetic acid (CCl3CO2H) is a corrosive acid that is used to precipitate proteins. The pH of a 0.050 M solution of trichloroacetic acid is the same as the pH of a 0.040 M HClO4 solution. Calculate Ka for trichloroacetic acid. I just don't know where to start. How ...
Monday, October 24, 2016 by Ryan

Chemistry - acids & bases
4. Calculate the pH of each of the solutions and the change in pH to 0.01 pH units caused by adding 10.0 mL of 2.37-M HCl to 320. mL of each of the following solutions. Change is defined as final minus initial, so if the pH drops upon mixing the change is negative. c) 0.115 M ...
Monday, October 24, 2016 by Ellen

Chemistry
What is the pH of distilled water supersaturated with CO2 at 100psi?
Monday, October 24, 2016 by Kato

Science (Chemistry) (Yield)
Using your mass of Mg (0.101g), and assuming all of the Mg burns in oxygen and forms the theoretical predicted product, calculate the theoretical yield of magnesium oxide. I wrote out the equation and it turned out to be: 2Mg+O2->2MgO I have my mass of Mg but how do I get ...
Monday, October 24, 2016 by Ray

Chemistry
SO CONFUSED PLEASE HELP!!! A certain radio wave has a wavelength of 7 inches. a. convert the wavelength of this radio wave into meters. (1 meter = 39.37) b. find the frequency of this radio wave.
Monday, October 24, 2016 by Clarissa

Chemistry
Illustrate how to prepare a 1:3 solution of 0.5M hydrochloric acid
Monday, October 24, 2016 by Adoma

Chemistry
calculate the volumes of acetone and ethanol that was used to mix together in order to produce 1 litre (1000ml) of equimolar mixture. helpful notes are, ethanol Mr=46 and a density (20 degrees C)=0.789g/ml, acetone Mr=58 and density (20 degrees C)=0.793g/ml
Monday, October 24, 2016 by Mara

Chemistry
In a three reactions system the first two reactions are endothermic with DeltaH values of 138kj and 241kj. if the final reaction is exothermic what is the minimum value of DeltaH3 that would make the overall reaction exothermic? explain your reasoning. i beleive the minimum ...
Monday, October 24, 2016 by Anonymous

chemistry
How much heat (in kilocalories) is evolved or absorbed in the reaction of 1.60 g of Na with H2O? 2Na(s)+2H2O(l)→2NaOH(aq)+H2(g), ΔH = -88.0 kcal (-368 kJ)
Monday, October 24, 2016 by Anonymous

chemistry
For each pair of compounds, predict which species will have the higher molar entropy at 298 K and 1 bar. Be sure to state your reasons for your choice. 1. N2(g) vs. F2(g) 2. ICl (g) vs. BrF(g) 3. 6Li(s) vs. 7Li(s)
Monday, October 24, 2016 by Joseph

Chemistry
0.4 moles ofpcl3 and 0.3 moles of pcl3 added to access ofC2H5OH then maximum no of moles obtained
Monday, October 24, 2016 by Abdul

Chemistry
0.4 moles of pcl3 and 0.3 moles of pcl3 added to access ofC2H5OH then maximum no of moles obtained
Monday, October 24, 2016 by Abdul

Chemistry
Na2CO3(aq)+ 2HNO3(aq)--> 2NaNO3+H2O(l)+CO2(g) how do I get net ionic?
Monday, October 24, 2016 by Anonymous

Chemistry
Zn(s)+HCl(aq)--> ZnCl2(aq)+H2(g) net ionic??
Monday, October 24, 2016 by Megan

Chemistry
How many moles of nitric oxide are formed from 0.60 mole of nitrogen dioxide
Monday, October 24, 2016 by Sienna

Chemistry
HCl(aq) + LiOH(aq)--> H2O(l) + LiCl(aq) Did I do this right? I need help on finding the net ionic equation
Monday, October 24, 2016 by Rachael

Chemistry
You have 2m^3 of a mineral ore sample. It has a mass of 1x10^4 kg. Calculate the density of the ore sample and express your results in g/cm^3 with appropriate scientific notation.
Monday, October 24, 2016 by Please Help

chemistry
Why do some reactions go to completion while others reach a state of equilibrium?
Monday, October 24, 2016 by lauren

Chemistry
How many grams of ethanol must be added to 500.0 g of water to make a solution that freezes at 0.00 degrees fahrenheit? The molal freezing point depression constant for water is 1.86 degree celsius over moles.
Monday, October 24, 2016 by Lucy

Chemistry
5.58g of Fe reacted with 3.0g of oxygen. How many moles of Fe were used?
Sunday, October 23, 2016 by Alyssa

Chemistry
In a three reactions system the first two reactions are endothermic with DeltaH values of 138kj and 241kj. if the final reaction is exothermic what is the minimum value of DeltaH3 that would make the overall reaction exothermic? explain your reasoning. i beleive the minimum ...
Sunday, October 23, 2016 by Anonymous

Chemistry
Balance the following redox reaction in basic solution. H2(g)+Fe3+(aq) ---> H2O(l)+Fe2+(aq)
Sunday, October 23, 2016 by Anonymous

Chemistry need asap
Situation: The Production of Nitric Acid can be achieved by the following process: Nitrogen monoxide gas(NO) + diatomic oxygen gas+ water (liquid) ===> Nitric Acid (aq) a. Show complete balanced reaction for process What I have: 4NO+ 3O2+ 2H2O > 4HNO3 b. The lab ...
Sunday, October 23, 2016 by John

Chemistry
When 26.16 g of iron is heated in the presence of excess chlorine gas, they will react to form 76.08 g of a compound called ntaining these 2 elements. If the molar mass of this compound is 644 g/mil find the molecular formula.
Sunday, October 23, 2016 by Josh

chemistry
proof that the energy of the first spectra line in Lyman series E =3/4Eo Eo=2.18×10-18
Sunday, October 23, 2016 by mesfin Gebre

Chemistry (atoms)
How many atoms of oxygen, O, are in 0.0595 moles of water?
Sunday, October 23, 2016 by Ray

Chemistry
0.3975 g of an oxide of divalent metal on reduction with hydrogen gives 0.090 g of water. The atomic weight of metal is: a) 63.5 b) 24 c) 55.5 d) 40
Saturday, October 22, 2016 by Avy

Chemistry, que 10
How many atoms are present in one formula unit of calcium hydrogen carbonate Ca(HCO3)2? Could someone explain to me why the answer is 11? Thank you.
Saturday, October 22, 2016 by Cheezel

Chemistry
The principal quantum number (n): 1) specifies the subshell of the orbital. 2) specifies the principal shell of the orbital. 3) specifies the 3-D shape of the orbital. 4) specifies the maximum number of electrons. 5) none of the above
Saturday, October 22, 2016 by Beth

Chemistry
According to the quantum-mechanical model for the hydrogen atom, which of the following transitions would produce light with longer wavelength: 3p to 2s or 4p to 2s? A) The 3p to 2s transition would produce light with longer wavelength. B) The 4p to 2s transition would ...
Saturday, October 22, 2016 by Sue

Chemistry
What happens to an atom when it absorbs energy? 1) The atom stores the energy for later use. 2) The atom re-emits the energy as electromagnetic radiation. 3) The extra energy increases the speed of the electrons in their orbitals. 4) The extra energy increases the oscillation ...
Saturday, October 22, 2016 by Beth

Chemistry
Calculate the wavelength, in nanometers, of the spectral line produced when an electron in a hydrogen atom undergoes the transition from the energy level n = 2 to the level n = 1.
Saturday, October 22, 2016 by Joseoh

Chemistry
Find the frequency if given energy 6.3x10^-19 Do I use the formula E=hf? 6.3x10^-19=6.626x10^-34(f) Then do I divide E and H?
Saturday, October 22, 2016 by Anonymous

Chemistry
calculate the mass ratio of 25% cacl2 solution and water to prepare 500 g of a 5% salt solution
Saturday, October 22, 2016 by Regan

Chemistry
What pressur would the propane gas sample have at 75Ml
Saturday, October 22, 2016 by Teela Lange

Chemistry
A chemist reacted 0.05 mol of sodium with water to form 50cm3 of sodium hydroxide what was the mass of sodium reacted Na+h2p-Noah+h2
Saturday, October 22, 2016 by Maria

Chemistry
A Solution Has A PH Of 3.4.What Is Its Hydrogen Ion Concentration?
Saturday, October 22, 2016 by Ola

Chemistry
The heat of combustion of C2H4 at 27 C at constant prssure is -333.3 Kcal. What will be the heat of combustion at constant volume considering the water to be in liquid state? (R=1.987 cal)
Saturday, October 22, 2016 by Sidharth

Chemistry
In a reversible reaction PCl5 ↔ PCl3 + Cl2, the value of K is 2.5. What will the partial pressure of Cl2 be?
Saturday, October 22, 2016 by Sidharth

chemistry
A Li2+ ion had its electron in an excited state. When the electron relaxed to the ground state (n = 1) a photon of light was emitted with an energy of 1.884×10−17 J. What energy level was the electron in before it transitioned to the ground state?
Friday, October 21, 2016 by malina

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Homework Help: Science