Tuesday
March 3, 2015

Homework Help: Science: Chemistry

Recent Homework Questions About Chemistry

Post a New Question | Current Questions

chemistry
What mass of solid sodium formate (of MW 68.01) must be added to 115 mL of 0.57 mol/L formic acid (HCOOH) to make a buffer solution having a pH of 4.16? Ka = 0.00018 for HCOOH. Answer in units of g
Saturday, January 31, 2015 at 4:37pm

chemistry
The enthalpy change for the following reaction is -483.6 kJ: 2H2(g) + O2(g) = 2H2O(g) Therefore, the enthalpy change for the following reaction is _______ kJ: 4H2(g) + 2O2(g) = 4H2O(g)
Saturday, January 31, 2015 at 2:02pm

Chemistry
What is the enthalpy change when 25 g's of PCl5 are decomposed /\ H= 90
Saturday, January 31, 2015 at 1:46pm

Chemistry
How many rams of 96.5% pure NaOH pellets do you need to make 1 liter of 1.5 N NaOH?
Saturday, January 31, 2015 at 12:10pm

chemistry
What is the specific heat capacity of ethanol (C 2H 6O) if a 18.3 g sample increased 12.3 C upon the addition of 553.0 J? The units are J/(g ·K)
Saturday, January 31, 2015 at 12:06pm

chemistry
The radiator in your car uses either water or ethylene glycol (anti-freeze) to remove heat from the engine and dissipate it to the outside air. If the water recirculation rate is 17.0 kg per minute of water and the water temperature leaving the engine and entering the ...
Saturday, January 31, 2015 at 12:01pm

chemistry
What is the molar mass of pentane if 4.18 ~ 1016 molecules of pentane weigh 5.00 ƒÊg?
Friday, January 30, 2015 at 9:54pm

chemistry
nearest star distance of 4.3 light years proxima centauri is the nearest star to our solar system. what is the distance to proxima centauri kilometers? the speed of light in space is 2.998 x10^8 m/s.
Friday, January 30, 2015 at 8:48pm

chemistry
A 0.97 m aqueous solution of an ionic compound with the formula MX has a freezing point of -2.5 ∘C .
Friday, January 30, 2015 at 7:11pm

Green Chemistry
The primary route for making copper iodide is by reacting potassium iodide with copper sulfate: 2CuSO4 + 4KI + 2Na2S2O3 ==> 2CuI + 2K2SO4 + 2NaI + Na2S4O6 Identify potential green chemistry and green engineering challenges of the reaction.
Friday, January 30, 2015 at 2:06pm

chemistry
I have to calculate the vapor pressure of water at 25.0 degrees celicus. The heat of vaporization of water is 40.65 kj/mol and the vapor pressure of water is 92.7 Torr at 50 degrees celcius. I know I should use log10 P=A- B/C+T but I don't know how to work it out.
Friday, January 30, 2015 at 2:16am

Chemistry
For a certain reaction, Kp = 3.54 at 325 C. Find delta G 598 K in kJ/mol.
Friday, January 30, 2015 at 1:15am

Chemistry
H= -20 kJ/mol and S= -75 kJ/mol A) is this process thermodynamicslly favored? B) does the equilibrium lie to the left, right, or close to the middle? For A I don't think it is. B?
Friday, January 30, 2015 at 12:20am

Chemistry
A chemical company claims that they are able to produce a certain product through thermodynamically favored process. Explain how this is possible?
Thursday, January 29, 2015 at 11:29pm

chemistry
Rank the following species according to the increasing energy needed to raise the temperature of 10.0 g of the substance by 25.0 ∘C. Aluminum-.897J/g water- 4.184J/g Stainless steel - .500J/g cast iron- .460J/g copper-.385J/g Can someone please show me how to figure this...
Thursday, January 29, 2015 at 11:02pm

Chemistry
In the process of separating pb2+ ions from cu+2 ions as sparingly soluble iodates, what is Pb2+ concentration when Cu+2 begins to precipitate as sodium iodate is added to a solution that is initially 0.0010M Pb(NO3)2 (aq) and 0.0010M Cu(NO3)2 (aq)? I know the answer is 1.8*10...
Thursday, January 29, 2015 at 8:57pm

chemistry
4FeS (s) + 7O2 (g) --> 2Fe2O3 (s) + 4SO2 (g) Entropy value for iron (II) sulfide is 67 J/K mol I don't understand how to find entropy
Thursday, January 29, 2015 at 8:21pm

Organic chemistry
What kind of reaction is occurring between potassium permanganate and cyclohexene? (I.e. Combination, double displacement, etc.
Thursday, January 29, 2015 at 8:08pm

Chemistry
I am having some chemistry problems. 3. The graph compares the 1s orbital energies for the F atom (Z = 9), the Ne+ ion (Z = 10), and the Na++ ion (Z = 11). (the graph shows F having an Orbital Energy of 692.45, Ne+ with 47.74, and Na++ with 33.52) a. How many electrons does ...
Thursday, January 29, 2015 at 8:07pm

Chemistry
Assuming equal concentrations and complete dissociation, rank these aqueous solutions by their freezing points. CoCl3 K2CO3 KNO3
Thursday, January 29, 2015 at 7:14pm

chemistry
if you burn 20.2g of hydrogen and produce 1.80x10^2g of water, how much oxygen reacted?
Thursday, January 29, 2015 at 6:57pm

Chemistry
Suppose you tired to carry out a double-replacement reaction by mixing together equal volumes of a solution that contained dissolved NaF and a solution that contained dissolved NaCl. Would you expect a reaction, if so write the balanced chemical equation?
Thursday, January 29, 2015 at 6:34pm

college chemistry
A sample of gas has an initial volume of 5.9L at a pressure of 759mmHg. If the volume of the gas is increased to 8.4L , what will the pressure be?
Thursday, January 29, 2015 at 6:03pm

Chemistry
27.31 mg of NH4Cl in 1.99 ✕ 10-2 L of solution cation ? And Anion ? (Molarity) I found the MW to be 62.48 and I converted Mg to 0.02731g idk what's wrong
Thursday, January 29, 2015 at 4:00pm

Chemistry
A 2.75 kg block of ice is heated until it completely melts. It is then heated again until it completely changes to water vapor. Is more energy required to melt the ice or to vaporize the liquid water.
Thursday, January 29, 2015 at 2:54pm

chemistry
If 1500 mg of rubbing alcohol is spilled in abox that measures 4m x 2m x 3m, what is the concentration of alcohol in mg. per cubic meter if it evaporates into gas?
Thursday, January 29, 2015 at 12:11pm

chemistry
What is the mass (in kilograms) of a cube of silver that measures 0.26m on each side
Thursday, January 29, 2015 at 11:03am

Chemistry
Which of the following is a balanced chemical equation H2O2 → H2O + O2 2 Fe2O3 + 3 C → 4Fe + 3CO2 SO2 + O2 + 2H2O →4H2SO4 2 Mg + HCl →MgCl2 + H2 not sure
Thursday, January 29, 2015 at 9:50am

Chemistry
Elements are constantly forming compounds, and the atoms of compounds are constantly being rearranged to form new combinations of atoms. True or false True
Thursday, January 29, 2015 at 9:26am

chemistry
calculate the amount of carbon dioxide that could produced when the one mole of carbon is burnt in 8gms of dry oxygen
Thursday, January 29, 2015 at 9:25am

Chemistry
consider the following reaction at 298K 4Al(s)+3O2(g) yields 2Al2O3(s) delta H= -3351.4 Kj find delta S sys find delta S surr find delta S unvi
Thursday, January 29, 2015 at 3:03am

chemistry 116
What is the specific heat capacity of aluminum if a 8.4 g sample increased 21.1 C upon the addition of 159.0 J? The units are J/(g ·K). q=cpxMxT is the equation my answer i got is 401.65 is that right bec i feel thats wrong
Thursday, January 29, 2015 at 2:02am

chemistry
what hybrid orbitals would be expected for the central atom for the followings a) BrF5 b) BeCl2 c) CH3Cl
Thursday, January 29, 2015 at 1:36am

Chemistry
How much of each of the following substances would you add to water to prepare 1.90 L of a 0.15 M solution? (a) H2SO4 from "concentrated" (18 M) sulfuric acid mL (b) HCl from "concentrated" (12 M) reagent mL (c) NiCl2 from the salt NiCl2·6 H2O g (d) ...
Wednesday, January 28, 2015 at 10:20pm

Chemistry
32.0=5.5x10^2(1/T)+14.2 Solve for T I am confused about what the first step would be to solving for T. Would I divide 5.5x10^2(1/T) and move it to the left side? Please help.
Wednesday, January 28, 2015 at 9:31pm

Chemistry
What is the formula of reactants for Dibromobis(Triphenylphosphine Oxide) Manganese(II)?
Wednesday, January 28, 2015 at 8:32pm

Chemistry
How would you make 100 mL of a carbonic acid buffer at 0.2 M and pH = 9.8 using 0.5 M HCO3 and either 0.1 M NaOH or 0.1 M HCl and water?
Wednesday, January 28, 2015 at 8:31pm

Science-Chemistry
Can you please help me solve r1/r2 = sqrt(M2/M1)for M1. My answer: M1=M2r2^2/r1^2 Is this correct?
Wednesday, January 28, 2015 at 8:03pm

Chemistry
Can you please help me solve r1/r2 = sqrt(M2/M1)for M1. My answer: M1=M2r2^2/r1^2 Is this correct?
Wednesday, January 28, 2015 at 7:47pm

chemistry
a 1.00*10^1 mL sample of an unknown liquid has a mass of 7.99 g. Calculate the density of the liquid using the proper number significant figures
Wednesday, January 28, 2015 at 7:37pm

Chemistry
Draw the Lewis structure for each of these molecules. 1. PH3 2. H2S 3. HCl 4. CCl4 5. SiH4
Wednesday, January 28, 2015 at 7:03pm

Chemistry
1. Write the balanced equation. Use ONLY this equation to reference how the reactions below will shift. Consider whether there is an addition, a removal, or no effect to the reaction. Co(H2O)6^2+ + 4Cl^- <--> CoCl4^2- + 6H2O 2. Write the equilibrium expression for the ...
Wednesday, January 28, 2015 at 6:16pm

chemistry
Find the percentage composition of (NH4)3PO4 What i dont understand is if the mass of the element isnt given how would i calculate?
Wednesday, January 28, 2015 at 5:29pm

chemistry
A solution of HClO is mixed and found to have a pH of 4.53. Find what the initial concentration of HClO was for this solution. Ka = 3.00 × 10−8 for HClO. Answer in units of mol/L please help this is due in 1 hour
Wednesday, January 28, 2015 at 5:08pm

chemistry
Find the initial concentration of the weak acid or base in an aqueous solution of pyridine (C5H5N) with a pH of 8.65. Kb = 1.80×10e-9 . Answer in units of mol/L
Wednesday, January 28, 2015 at 5:02pm

chemistry
Find the initial concentration of the weak acid or base in an aqueous solution of pyridine (C5H5N) with a pH of 8.65. Kb = 1.80×10−9 . Answer in units of mol/L
Wednesday, January 28, 2015 at 5:00pm

chemistry
A weak acid (HA) is found to ionize 20.9% when mixed at a concentration of 0.22 mol/L. What is the value of Ka for this acid?
Wednesday, January 28, 2015 at 4:45pm

chemistry
Calculate the mass of CaCO3 in a 100ml solution that contains 70% of CaCO3 and the density is 1.02g/ml at room temperature
Wednesday, January 28, 2015 at 4:07pm

chemistry
In a reaction, 41.8 g of chromium(III) oxide reacts with 14.8 g of aluminum to produce chromium and aluminum oxide. If 28.6 g of chromium is produced, what mass of aluminum oxide is produced? How do I go about solving this problem?
Wednesday, January 28, 2015 at 4:05pm

Chemistry
How can the atomic orbital be described in the quantum mechanical wave model of the orbitals? A. A collection of balloons B. A circular ring C. A probability density
Wednesday, January 28, 2015 at 2:16pm

chemistry
Core electrons shield what from the pull of the nucleus? A. Valence electrons B. Neutrons C. Protons I think the answer is a
Wednesday, January 28, 2015 at 2:12pm

Chemistry
Which of the following elements can be detected by XPS? A. Hydrogen and lithium B. Boron and helium C. Lithium and boron I think the answer is c.
Wednesday, January 28, 2015 at 2:09pm

chemistry
Nuclear magnetic resonance spectroscopy can be used to study which type of atoms? A. 16O B. 1H C. 2He
Wednesday, January 28, 2015 at 2:07pm

Chemistry
Which of the following are excited in ultraviolet photoelectron spectroscopy? A. Valence electrons B. Core electrons C. X-rays
Wednesday, January 28, 2015 at 2:05pm

chemistry
How is a spectrum obtained in NMR spectroscopy? A. Low-frequency radio waves bombard the atom and cause nuclei in a low spin state to move to a higher spin state. B. High-frequency ultraviolet rays bombard the atom and cause nuclei in a high spin state to move to a lower spin ...
Wednesday, January 28, 2015 at 2:04pm

Chemistry
Since chlorine has similar electronegativity as nitrogen, why can't chlorine form hydrogen bonds?
Wednesday, January 28, 2015 at 1:32pm

chemistry 116
The thermite reaction demonstrated in class requires high temperatures to start the reaction. A simple open flame is not enough to start the reaction. Once the reaction is going, then it generates enough heat to keep the reaction going. According to the literature on thermite...
Wednesday, January 28, 2015 at 1:05pm

chemistry
Give the shapes of CH3, O3, SnCl3, BrF3, I3
Wednesday, January 28, 2015 at 1:05pm

chemistry
Which of the following pairs of compounds has the same molecular shapes? a) AlCl3 and BF3 b) AlCl3 and PCl3 c) BF3 and NF3 d) CO2 and SO2
Wednesday, January 28, 2015 at 1:03pm

chemistry
which of the following have a covalent bond? AlCl3, NH3, H3O, H2O
Wednesday, January 28, 2015 at 12:54pm

chemistry
sodium cyanide nacn, contains how many single, double or triple bond?
Wednesday, January 28, 2015 at 12:49pm

chemistry
calculate the volume of concentrated 4M HCl that is needed to create a 1 L solution of 0.1 M HCl.
Wednesday, January 28, 2015 at 10:03am

chemistry
Calculate the pressures, P, in atmospheres at which the mean free path, l, of a hydrogen molecule will be 1.50 μm, 1.50 mm, and 1.50 m at 20.0 °C. The diameter of a H2 molecule is 270 pm. Which formula would I use?
Wednesday, January 28, 2015 at 9:48am

Chemistry
A 76.00-pound flask of mercury costs $132.00. The density of mercury is 13.534 g/cm3. a) Find the price of one cubic inch of mercury by calculating the following intermediate values.
Wednesday, January 28, 2015 at 12:26am

Chemistry
Suppose NaOH is added to the following system when it is at equilibrium. NH3 (aq) + H2O (l) = NH4 (aq) + OH (aq) a) in which direction will the reaction shift after the NaOH is added? b) will this stress increase or decrease the value of the reaction quotient, Q?
Tuesday, January 27, 2015 at 10:43pm

chemistry
Calculate the number of collisions per second of one hydrogen molecule at 24 °C and 1.00 bar. The diameter of a hydrogen molecule is 270 pm.
Tuesday, January 27, 2015 at 9:17pm

chemistry(limiting reagent)
Al2(SO3)3 + 6NaOH ----> 3Na2SO3 = 2 Al9OH)3 If 10.0g of Al2(SO3)3 is reacted with 10.0g of NaOH, determine the limiting reagent? help!!!
Tuesday, January 27, 2015 at 8:48pm

Chemistry
A sugar crystal contains approximately 1.7x10^17 sucrose. What is its mass in milligrams?
Tuesday, January 27, 2015 at 8:41pm

Chemistry
a mothball composed of naphthalene has a mas of 1.06g. how many napthalene molecules does it contain
Tuesday, January 27, 2015 at 8:38pm

chemistry
DNA is approximately 2.5nm in length. IF an average man is 5ft 10 in. tall, how many DNA molecules could be stacked to extend from the ground to the top of the head of an average man.
Tuesday, January 27, 2015 at 6:18pm

Chemistry
Calculate the normal boiling point of a compound that has a vapor pressure of 19.30kPa at 167 Fahrenheit and a vapor pressure of 1.86kPa at 77 Fahrenheit.
Tuesday, January 27, 2015 at 4:51pm

chemistry
A solution contains 5.00g of urea per 0.100kg of water (COCNH2)2 if the vapour pressure of pure water at 25°c is 23.7ton. What is the vapour pressure of the solution
Tuesday, January 27, 2015 at 4:12pm

Chemistry
When iron rusts in air, iron (III) oxide is produced. How many moles of oxygen react with 7.2 mol of iron in the rusting reaction? 4Fe(s)+3O2=2Fe2O3(s)
Tuesday, January 27, 2015 at 4:11pm

chemistry
A man pushes on a trunk with a force of 250 newtons. The trunk does not move. How much positive work is done on the trunk?
Tuesday, January 27, 2015 at 2:27pm

chemistry 116
A 36.0 g piece of copper at 130.0 C is placed in 50.0 g of water at 20.0 C. What is the temperature (in C) of the water once the system reaches equilibrium? The molar heat capacity of copper is 24.5 J/(mol·K). The specific heat capacity of water is 4.18 J/(g·K...
Tuesday, January 27, 2015 at 11:24am

chemistry
a 126g iron rod has a heat capacity of 58 j. What is the specific heat of iron?
Tuesday, January 27, 2015 at 8:27am

college chemistry
1)what is the final pH of CHECOOH 0.18M ,CHECOONa 0.08M, HNO3 0.08M and NaOH 0.08M ? Ka=1.8^10(-5) 2)what fraction of free edta is in the form )y^4-) at ph=10?
Tuesday, January 27, 2015 at 7:12am

chemistry
1)what is the final pH of CHECOOH 0.18M ,CHECOONa 0.08M, HNO3 0.08M and NaOH 0.08M ? Ka=1.8^10(-5) 2)what fraction of free edta is in the form )y^4-) at ph=10?
Tuesday, January 27, 2015 at 7:07am

chemistry
what mass of AgBr is produced when 100.0 mL of 0.150 M AgNO3 is added to 20.0 mL of 1.00 M NaBr?
Tuesday, January 27, 2015 at 4:30am

chemistry
2. A solution of I2 was standardized with ascorbic acid. Using a 0.1000-g sample of pure ascorbic acid, 25.32 mL of I2 were required to reach the starch end point. a) What is the molarity of the iodine solution?
Tuesday, January 27, 2015 at 2:50am

chemistry
When NH3 is treated with oxygen gas, the products obtained are N2(g) and H2O(l). If standard enthalpies of formation at 298 K for NH3(g) and H2O(l) are –46.00 kJ/mol and –286.0 kJ/mol respectively, calculate the enthalpy change of the reaction.
Tuesday, January 27, 2015 at 1:35am

Chemistry
A quantity of ice at 0.0 °C was added to 33.6 g of water at 45.0 °C to give water at 0.0 °C. How much ice was added? The heat of fusion of water is 6.01 kJ/mol, and the specific heat is 4.18 J/(g•°C).
Monday, January 26, 2015 at 10:23pm

chemistry
Calculate the amount of heat required to raise the temperature of a 39g sample of water from 6∘C to 23∘C.
Monday, January 26, 2015 at 7:59pm

chemistry
Identify the independent, dependent and controlled variables: a)Does the activity of soil affect plant growth? Independent: Dependent: Controlled: b)Does getting a good night's sleep affect performance on a test? Independent: Dependent: Controlled:
Monday, January 26, 2015 at 7:19pm

Chemistry
Calculate one Al(OH)3 formula unit in grams/unit. I keep arriving at the answer of 1.295 x 10-22 g/unit but my homework says it is incorrect! SOMEONE please help!!!
Monday, January 26, 2015 at 6:51pm

chemistry
How many moles of lead iodide are produced from 300. g of potassium iodide? Usie the reaction below. PB(NO3)+ KI = Ni9OH)2 + NaNO3
Monday, January 26, 2015 at 5:55pm

smhs chemistry
explaine whay vacuole in the plant cell is larger than the animal cell?
Monday, January 26, 2015 at 5:46pm

Chemistry
A student is instructed to standardize an approximately 2.5N KOH solution using a 0.500N H2SO4 stock solution. Describe the experimental procedure he/she must follow. I do not understand what procedure needs to be followed.
Monday, January 26, 2015 at 5:18pm

Chemistry
how much heat is required to warm a 215 g cup of water from 21 degree Celsius to 85 degree Celsius? Not sure what the formula is or how to set this up. I know the specific heat formula is heat/mass x change in temperature. Not sure if this applies to the question. Please help...
Monday, January 26, 2015 at 3:44pm

Chemistry
Daily diet consists of 120 g of carbohydrates, 65 g of fat, and 43 g of protein. How many calories does this diet provide daily? My work/answers: 120 g x 4 g/calories of carbs = 48 g/cal 65 g x 9 g/calories of fats= 585 g/cal 43 g x 4 g/calories of protiens = 172 g/cal Total: ...
Monday, January 26, 2015 at 3:42pm

Chemistry
Person consumes 1995 Calories/day. How many is this in kJ My answer/work: 1995 x 1000 cal/1 Cal x 4.184J/1 cal x 1 kj/1000J= 8347.08kj Let me know if I did anything wrong and give me a hint on what I can do to fix it thank you :)
Monday, January 26, 2015 at 3:40pm

Chemistry
Calculate the following temperatures 1. Its 18 F. What is this in C? 2. Calculate this temperature (from question #1) to K 3. Convert 38.2 C to F My answers 1. -7.7 C 2. 265.3 K 3. 100.76 F Let me know what I did wrong if I'm incorrect thank you :)
Monday, January 26, 2015 at 3:38pm

english
School has increased in its difficulty over the years. In the past, kindergarten was carefree; all I had to do was finger paint, crafts, and daily nap-times, which gave me the rest I needed. During my elementary years, math went from adding and subtracting to multiplication ...
Monday, January 26, 2015 at 11:15am

chemistry
You wish to prepare 100.0 mL of a 800.0 ppm w/v sodium (MW = 22.9897 g/mol) solution. How many grams of sodium dichromate dihydrate (Na2Cr2O7·2H2O, MW = 297.998 g/mol) are needed to prepare this solution?
Monday, January 26, 2015 at 1:31am

chemistry
A human body is 55% water. A person has a mass of 78 kg. How many kg. of water is in this person's body?
Sunday, January 25, 2015 at 9:18pm

Chemistry
I would i calculate the E.F of nitrogen 21% hydrogen 7.48% chlorine 66.35%
Sunday, January 25, 2015 at 6:00pm

Chemistry
B) if you are holding a piece of Silicon that weighs 28.1 gram (atoms mass of Silicon is 28.1) how many silicon atoms are you holding? (Answer in moles of atoms and in atoms )
Sunday, January 25, 2015 at 5:45pm

chemistry
3. One problem the researchers faced was an uncertainty about whether the signals observed in certain mass spectrometry data were, in fact, due to lead isotopes. Explain why this was a problem. In other words, why wasn't information about the mass of the isotopes ...
Sunday, January 25, 2015 at 4:18pm

chemistry
Diborane (B2H6) is a highly reactive boron hydride, which was once considered as a possible rocket fuel for the U.S. space program. Calculate ∆H for the synthesis of diborane from its elements, according to the equation 2 B (s) + 3 H2 (g) → B2H6 (g) using the ...
Sunday, January 25, 2015 at 4:09pm

Chemistry
3. Is determining the excess reactant and limiting reactant an important part of a synthesis reaction? Is it an important part of a decomposition reaction? Explain.
Sunday, January 25, 2015 at 2:51pm

Pages: <<Prev | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | Next>>

Post a New Question | Current Questions

Homework Help: Science

Members