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November 20, 2014

Homework Help: Science: Chemistry

Recent Homework Questions About Chemistry

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chemistry
The radius of a strontium atom is 215 pm. How many strontium atoms would have to be laid side by side to span a distance of 4.47 mm?
Monday, September 8, 2014 at 6:58pm

Chemistry
The standard free energy of activation of a reaction A is 73.4 kJ mol–1 (17.5 kcal mol–1) at 298 K. Reaction B is one million times faster than reaction A at the same temperature. The products of each reaction are 10.0 kJ mol–1 (2.39 kcal mol–1) more stable...
Monday, September 8, 2014 at 6:00pm

Chemistry
A reaction has a standard free-energy change of –12.40 kJ mol–1 (–2.964 kcal mol–1). Calculate the equilibrium constant for the reaction at 25 °C.
Monday, September 8, 2014 at 5:58pm

chemistry
You have a metal tank containing 74.0 moles of nitrogen gas at a pressure of 15.0 atm. If the pressure is measured at a temperature of 25.0 °C, then the volume of the tank must be ___ liters. (Round your answer to one decimal place and do not include units with the number.)
Monday, September 8, 2014 at 5:36pm

Chemistry
Name the property that each change depends on. Then classify the property as either chemical or physical. a) You separate a mixture of gravel and road salt by adding water to it b) Carbon dioxide gas freezes at a temperature of -78C
Monday, September 8, 2014 at 4:39pm

Chemistry 2
Pure nitrosyl bromide, NOBr at 0.762 M is placed into a sealed vessel and heated up to 400 K. When the system reaches equilibrium, it is found that 65.1% of the nitrosyl bromide has decomposed to nitrogen monoxide and bromine. Determine Kc for this reaction at 400 K: 2 NOBr(g...
Monday, September 8, 2014 at 4:05pm

Organic Chemistry
Rank the given compounds based on their relative Brønsted acidities. H-CH3 H-OH H-Cl H-F H-NH2
Monday, September 8, 2014 at 3:40pm

chemistry
at a temperature of 5 celsius, 21.5 mg of a non electrolyte is dissolved in enough water to make a 150.0 ml solution. the osmotic pressure of the solution is 0.200 atm. what is the molar mass of the substance dissolved
Monday, September 8, 2014 at 12:05pm

CHEMISTRY
lABEL THE VARIABLES IN THE EQUEATION BELOW WITH THE CORRECT UNIT RATE=k(A) UNITS: S-1, M, M-2 S-1, M.S-1, M.S, M-1S-1 WHAT IS RATE WHAT IS K WHAT IS A
Monday, September 8, 2014 at 4:51am

CHEMISTRY
LABLE THE VARIABLES IN THE EQUATION BELOW WITH THE CORRECT UNITS RATE=k(a)(b) UNITS M-2S-1, M, M.S-1, M-1S-1, S-1, M.S WHAT IS K WHAT IS A WHAT IS B
Monday, September 8, 2014 at 4:46am

chemistry
Express the rate of the reaction in terms of the change in concentration of each of the reactants and products. 2D(g)+3E(g)+F(g)>>>>2G(g) + H(g) when D is decreasing at 0.30 MOL/Ls, how fast is (H) increasing?
Monday, September 8, 2014 at 3:52am

chemistry
Archeologists can determine the age of artifacts made of wood or bone by measuring the amount of the radioactive slope 14C present in the object. The amount of isolope decreases in a first-ordrr process. If 12.8% of the original amount of 14C is present in a wooden tool at the...
Monday, September 8, 2014 at 2:40am

chemistry
What mass of cesium bromine must be added to a 0.500 liter of water (d=1.00 g/ml) to produce a 0.981m solution? what are the mole fraction and mass percent of CsBr?
Monday, September 8, 2014 at 2:25am

chemistry
calculate the molality, molarity, and mole fraction of NH3 in an 12.80 mass % aqueous solution (d=0.9651 g/ml)
Monday, September 8, 2014 at 2:18am

chemistry
A 6.0-ft person weighs 177lb. express this person's height in meters and weight in kilograms.
Sunday, September 7, 2014 at 11:59pm

Chemistry
Suppose you have two 100-{\rm mL} graduated cylinders. In each cylinder there is 58.5mL of water. You also have two cubes: One is lead, and the other is aluminum. Each cube measures 2.0cm on each side. After you carefully lower each cube into the water of its own cylinder, ...
Sunday, September 7, 2014 at 11:37pm

chemistry
if the average speed of a helium atom at a certain temperature is 1130. m/s, what is the speed in miles per hour? (1 mi =1609m)
Sunday, September 7, 2014 at 10:30pm

chemistry
convert 1.65 A(circle above the A) to nanometers (scientific notation)
Sunday, September 7, 2014 at 10:24pm

chemistry
convert 3.43 A(with circle above the A) to meters(scientific notation)
Sunday, September 7, 2014 at 10:22pm

chemistry
convert 140 amu to kilograms (scientific notation)
Sunday, September 7, 2014 at 10:14pm

chemistry
convert 278 amu to grams (scientific notation)
Sunday, September 7, 2014 at 10:10pm

chemistry
What is the wavelength λ of the photon that has been released by−2.05×10−18 J?
Sunday, September 7, 2014 at 9:38pm

chemistry
19.0 kg /0.036 m(3)(cube)=??
Sunday, September 7, 2014 at 9:05pm

Chemistry
carry out the following conversions.Enter your answer in scientific notation a)232 amu to grams (b)135 amu to kilograms (c)3.03 amu A to meters (d)3.19 A to nanometers
Sunday, September 7, 2014 at 8:48pm

chemistry
1.4602 cm x 2.488 cm x 10.399 cm =??
Sunday, September 7, 2014 at 8:42pm

chemistry
calculate the density of a solid if a cube meassuring 2.04cm on one side has a mass of 124g ......................g/cm3 calculate the mass of a cube the same substance measuring 7.97cm on one side enter your answer in scientific notaation ..................x10 g
Sunday, September 7, 2014 at 8:38pm

a level chemistry
two most abundant atmospheric gases react to a small extent at 298K in the presence of a catalyst to achieve dynamic equilibrium: N2(g) + O2(g) ->/<- 2NO(g) Kp= 0.30 Partial pressure of N2 and O2 = 0.78atm 1dm3 flask and equilibrium established after 30min. temperature ...
Sunday, September 7, 2014 at 8:03pm

Chemistry
How much energy in kilojoules is released when 25.0 g of ethanol (C2H5OH) vapor at 93.0 C is cooled to -10 C? Ethanol has mp = -114.1 oC, bp = 78.3 oC, ΔHvap = 38.56 kJ/mol, and ΔHfus = 4.93 kJ/mol. The molar heat capacity is 112.3 J/(K.mol) for the liquid and 65.6 J...
Sunday, September 7, 2014 at 7:56pm

Chemistry
A household receives a $155 electricity bill. The cost of electricity is $0.129/kWh.How much energy, in joules, did the household use?
Sunday, September 7, 2014 at 7:37pm

chemistry
which pairing below does not correctly match the scientist with the contribution to the understanding of the atom A. Proust and the realization that the elements of compounds are found in certain proportions by mass B. Thomson and the law of definite proportions. C. Dalton and...
Sunday, September 7, 2014 at 6:57pm

CHEMISTRY
Ch3CN(CH3)C2H5 is my kekule drawing ok? I drew it and uploaded a picture. oi61. tinypic . com/2vmztir.jpg
Sunday, September 7, 2014 at 4:02pm

Chemistry
NaHCO3 + HCl = NaCl + H2O + CO2 The there are .0489 moles of CO2, and HCL is 6M. find the amount of HCL in mL and the grams of NaHCO3
Sunday, September 7, 2014 at 3:59pm

Chemistry
59.0 mL of a 1.60 M solution is diluted to a total volume of 268 mL. A 134-mL portion of that solution is diluted by adding 111 mL of water. What is the final concentration? Assume the volumes are additive.
Sunday, September 7, 2014 at 2:50pm

Chemistry- urgent!
Perform the following operations and express the results in the correct number of significant digits or decimal places. Express all results in scientific notation. Please help me I'm so confused on how to do this!! 15. (1.71 x 10^6)(6.73 x 10^-8)/2.25 x 10 20. (533)(24) 21...
Sunday, September 7, 2014 at 12:57pm

chemistry
An ore contains Fe3O4 and no other iron. The iron in a 65.46 gram sample of the ore is all converted by a series of chemical reactions to Fe2O3. The mass of Fe2O3 is measured to be 37.9 grams. What was the percent Fe3O4 in the sample of ore? Answer in units of %
Sunday, September 7, 2014 at 9:25am

Chemistry (concentrations)
A liquid mixture has 12.6 parts per thousand of MgCl2 dissolved. Calculate the [Cl-] in ppt? Im stuck plz help!
Sunday, September 7, 2014 at 7:15am

chemistry
For the electrolysis of molten potassium bromide: Write the equation for the overall reaction.
Sunday, September 7, 2014 at 4:10am

Organic chemistry
A 200.0g sample of glucose(180.16g/mol, Kmp=1.86 degrees celcius/m, mp=146 degrees celcius)is contaminated with 5.000g of table salt, sodium chloride(58.44g/mol, mp=801 degrees celcius). What would the expected melting point of the mixture be?
Sunday, September 7, 2014 at 2:17am

chemistry
which pairing below does not correctly match the scientist with the contribution to the understanding of the atom A. Proust and the realization that the elements of compounds are found in certain proportions by mass B. Thomson and the law of definite proportions. C. Dalton and...
Sunday, September 7, 2014 at 1:43am

chemistry
in a reversable reaction H2+I2=2HI,what will happen to the equilibrium if the volume is decrease?
Sunday, September 7, 2014 at 1:00am

chemistry
which of the following statements correctly describes energy levels? A. Electrons can never move to a higher or lower energy level. B. In its outermost energy level, oxygen has 4 valence electrons C. The Second energy level holds a maximum of eight electrons. D. The greater ...
Saturday, September 6, 2014 at 10:43pm

Chemistry
determine the location of the non significant zeros by rewriting the number and placing a bar over the zeroes that are not significant. 1. 8040 2. 4.2 x 10^5 3. 4.70 x 10^-6
Saturday, September 6, 2014 at 9:25pm

Chemistry
Give the number of significan figures and decimal places in each of the following: 1. 80750 X 10^-2 2. 9.9000 X 10^8 3. 30.366 X 10^4 cm^3 4. 0.11692 X 10^-5
Saturday, September 6, 2014 at 8:29pm

chemistry
In the electrolytic refining of copper, write equation for the reaction of the impure copper.
Saturday, September 6, 2014 at 4:40pm

chemistry
Write the anodic reaction for the electrolysis of concentrated zinc chloride solution. (a) Using plantium electrodes. (b) Using zinc electrodes
Saturday, September 6, 2014 at 4:39pm

Chemistry
Find the pH of 1.0E-8 M H2S04 (H2SO4 <==> 2H^+ + SO4^2-) I have got answer to be 7.70, can you confirm the answer for me please? If it is not good, i'll be very grateful if you could leave some guides.
Saturday, September 6, 2014 at 3:49pm

Chemistry
What is the volume of 1.25 lb of mercury? The density of mercury is 13.546g/mL.
Saturday, September 6, 2014 at 3:36pm

Chemistry
How many molecules of PbCl2 are produced when 5.00 g of Pb(NO3)2 reacts with HCl?
Saturday, September 6, 2014 at 1:31pm

Chemistry
Why are alum rystals not supposed to washed in pure water?
Saturday, September 6, 2014 at 11:58am

Chemistry
A 14.0 kg sample of lead is measured out at 4 oC. what is the specific gravity of lead?
Saturday, September 6, 2014 at 11:53am

Chemistry
A 14.0 kg sample of lead is measured out at 4 oC. Using the table on page 34, what is the specific gravity of lead?
Saturday, September 6, 2014 at 11:08am

Chemistry
A gold nugget that weighs 20.053 g on the balance is lowered into a graduated cylinder filled with ethanol. If the initial ethanol level was 10.10 mL, what will the final ethanol level be?
Saturday, September 6, 2014 at 11:08am

Chemistry
A gold cube that measures 3.00 cm on each side is lowered into a volumetric cylinder that has an initial reading of 5.75 mL. What will be the new water level?
Saturday, September 6, 2014 at 11:07am

chemistry
What is the approximate Cl–Ca–F bond angle in the following molecule?
Saturday, September 6, 2014 at 7:44am

chemistry
what topics are under periodic chemistry?
Saturday, September 6, 2014 at 6:46am

Chemistry
A farmer supplies 1250.0 kg of a fertilizer that contains 10& nitrogen to his fields each year. Fifteen percent of the fertilizer washes into a river that runs through the farm. If the river flows at an average rate of 0.165 cubic feet per second, what is the additional ...
Saturday, September 6, 2014 at 12:40am

chemistry
Given that PVnR=T, solve for n if P = 36.0, V = 8.6, R = 0.08, and T = 200
Friday, September 5, 2014 at 10:40pm

chemistry
Rearrange and solve the following equation for λ: hvλ=mv2
Friday, September 5, 2014 at 10:39pm

chemistry
You weigh an empty dish and find its mass to be 48.0 grams. After you add a volume of salt water to the dish the mass of the dish and salt water is now 74.0 grams. After 100% of the water has been evaporated, the mass of the dish and the remaining salt is 52.5 grams. What is ...
Friday, September 5, 2014 at 10:37pm

chemistry
The average cooling rate of a cup of coffee is 24 °C per minute, and you can begin to sip the coffee when it is 60 °C. How long must you wait before you can begin to sip the coffee if the initial coffee temperature is 156 °C?
Friday, September 5, 2014 at 10:20pm

chemistry
Density (d) is mass (m) divided by volume (V) (d = mV). Mass is typically measured in grams (g), while volume is typically measured in milliliters (mL). How much volume will 550 g of a solution with a density of 1.10 g/mL occupy?
Friday, September 5, 2014 at 10:17pm

chemistry
Flask A contains 100 milliliters of a solution with a pH of 5. After you add 100 milliliters of a solution from Flask B, the pH rises to 7. What was the pH of the solution in Flask B?
Friday, September 5, 2014 at 9:04pm

chemistry
explain the fire symbol
Friday, September 5, 2014 at 6:32pm

physical chemistry
at least 6 sources of error of determining concentration quotient of FeSCN? plzzz sir
Friday, September 5, 2014 at 5:55pm

physical chemistry
salam.... plz give me some sources of error of determining concentration quotient of FeSCN? plzz urgent
Friday, September 5, 2014 at 5:45pm

Chemistry
How many chemical reactions are possible regarding the formation of carbonic acid and the dissolving of calcite? A. 23 B. 10 C. 2 [D.] 3 ?
Friday, September 5, 2014 at 5:23pm

Chemistry
a solution of OH- ions is added to a beaker of pure water at 25 C, to a final concentration of 872 nM. Calculate the pH of the solution. I know that pH=-log[H+], but I'm still really confused as to how to convert the nM to M and how to solve this problem.
Friday, September 5, 2014 at 3:42pm

Chemistry
Draw the isomers for C2h2 Is this correct? CH3-CH=CH-CH3 There's only one possible isomer.
Friday, September 5, 2014 at 3:12pm

Chemistry
If I count out Avogadro's number if CO2 molecules how much will my piles of molecules weigh? Can someone show me how to get the answer. I know the answer is 44g
Thursday, September 4, 2014 at 11:43pm

chemistry
A sprinter set a high school record in track and field, running 200.0 m in 21.0s . What is the average speed of the sprinter in kilometers per hour?
Thursday, September 4, 2014 at 10:14pm

chemistry
a mixture of gases is prepared for laboratory experiments by combining 4.2 L of oxygen, 0.71 L of nitrogen, and 0.22 L of carbon dioxide. Determine the percentage of nitrogen in the mixture.
Thursday, September 4, 2014 at 9:22pm

chemistry
_____ was responsible for first grouping elements into triads based on similar properties. A. Döbereiner B. Moseley C. Dalton D. Mendeleev
Thursday, September 4, 2014 at 9:06pm

Chemistry
What will be the freezing point of a solution made by dissolving 5.25 g of naphthalene (C10H8) in 100.0 g benzene (C6H6?). The normal freezing point of benzene is 5.5°C and K f (benzene) is 5.12°C / m.
Thursday, September 4, 2014 at 7:06pm

Chemistry
A 6.8 g sample of metal pellets is placed into a graduated cylinder holding 7.1 ml of water. After the pellets are added, the water level stands at 9.30 ml. Determine the density of the pellets. (show all work) I've tried 6.8 g / 9.30 ml and .97-.71 to get .24 but I'm ...
Thursday, September 4, 2014 at 5:47pm

CHEMISTRY
a concentration-time study of the gas phase reaction a 2A3 -> 3A2 produced the data in the table below. time [A3] (M) [A2] (M) 0 4.00 *10^-4 0 10 2.00 *10^-4 3.00 *10^-4 20 1.00 *10^-4 4.50 *10^-4 10 5.00 *10^-5 ? A) What is the concentration of A2 in the time interval 20-...
Thursday, September 4, 2014 at 2:48pm

chemistry 101
A patient receives 2700mL of an IV solution containing 4g g of glucose per 100 mL .How much energy, in kilojoules, does the patient obtain from glucose, a carbohydrate? please help I keep getting the wrong answer
Thursday, September 4, 2014 at 2:36pm

chemistry
which topics are under periodic chemistry II?
Thursday, September 4, 2014 at 10:41am

chemistry
what is the initial rate of the reaction, in mol/(L*s), under theswe conditions? Concentration=0.40 mol/L
Thursday, September 4, 2014 at 9:35am

chemistry 12
a chemical reaction released 50.0kJ of energy as it heated a sample of water from 17.0 degrees celsius to 75.0 degrees Celsius, what mass of water was heated? I have no clue as to how to do this! can anyone help?
Thursday, September 4, 2014 at 8:24am

Chemistry
How to get results and balance the following equation FeC2O4 + H2SO4 + K2C2O4 + H2O2
Wednesday, September 3, 2014 at 11:48pm

chemistry
What type of chemical rxn is Na2SO4(aq) +Ba(NO3)2(aq) the product is BaSO4(s) + 2NaNO3(aq)?what is its net ionic equation?
Wednesday, September 3, 2014 at 9:26pm

chemistry
nitrosyl bromide, NOBr is formed from NO and Br2-. Experiments show that this reaction is second order in NO and first order in Br2. what is the rate equation for this reaction?
Wednesday, September 3, 2014 at 6:30pm

chemistry
'A patient receives 2900mL of an IV solution containing 3g of glucose per 100 mL. How much energy, in kilocalories, does the patient obtain from glucose?
Wednesday, September 3, 2014 at 6:13pm

Chemistry
A container is fabricated from steel having a thickness of 0.500 inch and an average density of 7.85 g/cm3. (You may assume that the container is cylindrical with hemispherical ends.) What is the mass of the filled container, assuming that liquid propane has a density of 0....
Wednesday, September 3, 2014 at 5:29pm

College Chemistry
Suppose there are two known compounds containing the generic elements X and Y. You have a 1.00-g sample of each compound. One sample contains 0.29 g of X and the other contains 0.38 g of X. Identify plausible sets of formulas for these two compounds. Check all that apply. XY ...
Wednesday, September 3, 2014 at 3:57pm

Chemistry
A syrup is added to an empty container with a mass of 102.00g . When 0.133 pint of syrup is added, the total mass of the container and syrup is 196.34g . (1 qt = 2 pt)
Wednesday, September 3, 2014 at 3:28pm

Chemistry
Copper is composed of two naturally occurring isotopes: Cu−63 (69.170%) and Cu−65. The ratio of the masses of the two isotopes is 1.0318.
Wednesday, September 3, 2014 at 3:05pm

Chemistry
Naturally occurring cobalt consists of only one isotope, 59Co, whose relative atomic mass is 58.9332. A synthetic radioactive isotope of cobalt, 60Co, relative atomic mass 59.9338, is used in radiation therapy for cancer. A 1.8276g sample of cobalt has an apparent "atomic...
Wednesday, September 3, 2014 at 3:01pm

Analytical Chemistry
What are the most common sources of error in weighing solid samples ?
Wednesday, September 3, 2014 at 1:36pm

Chemistry
How much energy, in calories, is needed to heat 18 cubic centimeters of fat from 25 degrees Celsius to 35 degrees Celsius?
Wednesday, September 3, 2014 at 11:43am

chemistry
An unknown substance has a mass of 53.9 g and occupies a volume of 35.4 mL. What is its density in g/mL?
Wednesday, September 3, 2014 at 10:15am

Chemistry
Calculate the percentage by mass for Carbon in C2H2
Wednesday, September 3, 2014 at 6:58am

Chemistry
Calculate the percentage by mass for Carbon in C2H2
Wednesday, September 3, 2014 at 12:46am

Chemistry
When a 1.1 gram ice cube is placed into a 10.0 mL graduated cylinder, the level of water inside the graduated cylinder raises 1.20 mL. What is the Density of the ice cube? My Work: Density = 1.1g/10.0 mL + 1.20 mL? my answer came out to be; Density= .0982 g/mL
Wednesday, September 3, 2014 at 12:17am

Chemistry(Please help)
For a carbon atom that is sp2 hybridized, I understand that the electron configuration would be Yes, 1s2 2s1 2p3 which is a 2s up arrow,and 3 orbtials that are 2p up arrows but then since the four bonds hybridize to form four sp3 hybrid bonds how do I write this? Also for an ...
Tuesday, September 2, 2014 at 11:33pm

Chemistry
Question: how do you dilute something with a huge concentration to the same thing with a smaller concentration? For example: How do you dilute a 36 M solution of NaOH to a 6 M solution of NaOH?
Tuesday, September 2, 2014 at 10:26pm

Chemistry
Analytical Chemistry question: Find the pH and the concentration of each species of lysine in a solution of 0.0010 M lysine*HCL. I know that the pKAs of lysine are (1.77)(CO2H) 9.07 (-NH3) 10.82 ( -NH3) but I am not sure where to go from there.
Tuesday, September 2, 2014 at 9:58pm

Chemistry
How many moles of chlorine atoms are present in 4.8x10^20 molecules of carbon tetrachloride?
Tuesday, September 2, 2014 at 9:47pm

chemistry
Which of the following statements correctly describes energy levels? A. Electrons can never move to a higher or lower energy level. B. In its outermost energy level, oxygen has 4 valence electrons C. The second energy level holds a maximum of eight electrons. D. The greater ...
Tuesday, September 2, 2014 at 9:27pm

Chemistry
What is the osmotic pressure of a solution made from dissolving 60.0g of glucose, C6H12O6, in 450 mL of water at 10.0∘C?
Tuesday, September 2, 2014 at 8:42pm

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