Saturday
August 23, 2014

Posts by tomi


Total # Posts: 66

Chemistry
nitrogen gas is at 2.00. c, 2.00 atm pressure and occupies a volume of 10.01. Assume nitrogen is an ideal gas, how many moles of the gas are present?
November 4, 2012

Consumer math !!!! please check
Determine the total in Dexter's account after the second month using the information below. Dexter Banler's account Principal: $1,604 Rate: 10% compound Length of period: month >$3208.00 $1764.40 $1630.85 3. Ray Sugar's account Principal: $1,700 Rate: 9.5% ...
May 24, 2012

physics
5. If a quantity increases as a second quantity decreases and decreases as the second quantity increases, the two quantities are said to be: A_Directly proportional B_Inversely proportional C_Completely unrelated D_Blue and red
May 22, 2012

calculus
from the first principles,find the deriviative of 3/x with espect to x
February 4, 2012

designer
For which figure type are the line of this gown most flattering?.A tall.B. short or plump.C.Thin. D. Average
September 4, 2010

chem
1.Pippete 20ml of 0.1M acetic acid and 20ml of 0.1M NaOH into a 100ml beaker (Remember that the final volume of this solution is the sum of the volumes of the acetic acid and NaOH solutions that have been mixed) 2. Pippete 20ml of 0.1 acetic acid into another 100ml beaker and ...
April 26, 2009

biology
If you were to use an aquatic plant for your starting material, what would you expected to see in terms of pigments and absorption spectra, in comparison to results from a spinach? Explain.
April 26, 2009

chem
A sample of 7.80L of NH3 (ammonia) gas at 22 degrees and 735mmHg is bubbled into a 0.350L solution of 0.400M HCL(hydrochloric acid). The Kb value for NH3 is 1.8x10-5 Assuming all the NH3 dissolves and that the volume of the solution remains at 0.350L , calculate the pH of the ...
April 23, 2009

chem
A 75.0mL sample of 1.56×10−2M Na2SO4(aq) is added to 75.0mL of 1.22×10−2M of Ca(NO3)2(aq). What percentage of the Ca+ remains unprecipitated?
April 23, 2009

chem
You are asked to bring the pH of 0.500L of 0.450M NH4Cl to 7.00. a) Which of the following solutions would you use: 10.0M HCl or 10.0M NH3? I figured that one would use the 10.0M NH3 b)How many drops (1 drop 0.05mL) of this solution would you use?
April 23, 2009

chem
A sample of 7.80L of NH3 (ammonia) gas at 22 degrees and 735mmHg is bubbled into a 0.350L solution of 0.400M HCL(hydrochloric acid). The Kb value for NH3 is 1.8x10-5 Assuming all the NH3 dissolves and that the volume of the solution remains at 0.350L , calculate the pH of the ...
April 22, 2009

chem
A 75.0mL sample of 1.56×10−2M Na2SO4(aq) is added to 75.0mL of 1.22×10−2M of Ca(NO3)2(aq). What percentage of the Ca+ remains unprecipitated?
April 22, 2009

chem
You are asked to bring the pH of 0.500L of 0.450M NH4Cl to 7.00. a) Which of the following solutions would you use: 10.0M HCl or 10.0M NH3? I figured that one would use the 10.0M NH3 b)How many drops (1 drop 0.05mL) of this solution would you use?
April 22, 2009

chem
A sample of 7.80L of NH3(ammonia) gas at 22 degrees Celsius and 735torr is bubbled into a 0.350L solution of 0.400M HCl (hydrochloric acid). The Kb value for NH3 is 1.8x10-5. Assuming all the NH3 dissolves and that the volume of the solution remains at 0.350L , calculate the ...
April 16, 2009

chem
Calculate [H3O] in the following solutions. 5.15x10-2M HCl and 7.62x10-2M NaC2H3O2 Responses HCl + NaC2H3O2. It appears there is an excess of H^+ which will react with NaC2H3O2 to form HC2H3O2. That gives you a buffer of C2H3O2 and HC2H3O2 and you use the H-H equation to solve...
April 16, 2009

chemistry
Calculate [H3O] in the following solutions. a)4.0×10−2M HCl and 8.0×10−2M HOCl b)0.105M NaNO2 and 5.00×10−2M HNO2 c)5.15x10-2M HCl and 7.62x10-2M NaC2H3O2
April 15, 2009

chem
The following equation describes the oxidation of an acidified solution of sodium oxalate (Na2C2O4) by potassium permanganate(KMnO4) 5C2O4 + 2MnO4 + 16H2SO4 --> 10CO2 + 2Mn + 16HSO4 + 8H20 What volume of 0.127M sodium oxalate in sulphuric acid will react with 3.57g of ...
April 7, 2009

chem
Lead metal is added to 0.140M Cr^+3(aq). Pb(s)+ 2Cr^3+(aq)---> Pb^2+(aq) + 2Cr^2+(aq) a)What is [Pb^2+] when equilibrium is established in the reaction? b)What is [Cr^2+] when equilibrium is established in the reaction? c)What is [Cr^3+] when equilibrium is established in ...
April 3, 2009

chem
Lead metal is added to 0.140M Cr^+3(aq). Pb(s)+ 2Cr^3+(aq)---> Pb^2+(aq) + 2Cr^2+(aq) a)What is [Pb^2+] when equilibrium is established in the reaction? b)What is [Cr^2+] when equilibrium is established in the reaction? c)What is [Cr^3+] when equilibrium is established in ...
April 2, 2009

chem
The following reaction is used in some self-contained breathing devices as a source of O2. 4KO2(s) + 2C02(g)---> 2K2CO3(s) + 3O2(g) Suppose that a sample of CO2(g) is added to an evacuated flask containing KO2(s) and equilibrium is established. The equilibrium partial ...
April 2, 2009

chem
The pH of saturated Sr(OH)2 is found to be 13.12. A 15.0ml sample of saturated Sr(OH)2 is diluted to 250.0ml in a volumetric flask. A 15.0ml sample of the diluted Sr(OH)2 is transferred to a beaker, and some water is added. The resulting solution requires 29.3ml of a HCl ...
April 2, 2009

chemistry......plz help
A solution is prepared by dissolving 10.00g of a monobasic salt in a total volume of 1.00litres. Th pH of this solution was measured at 13.07 and a conductivity experiment determined that this salt was completely ionized in solution. What is the molecular weight of this ...
March 24, 2009

chemistry
A solution is prepared by dissolving 10.00g of a monobasic salt in a total volume of 1.00litres. Th pH of this solution was measured at 13.07 and a conductivity experiment determined that this salt was completely ionized in solution. What is the molecular weight of this ...
March 23, 2009

chemistry
A solution is prepared by dissolving 10.00g of a monobasic salt in a total volume of 1.00litres. Th pH of this solution was measured at 13.07 and a conductivity experiment determined that this salt was completely ionized in solution. What is the molecular weight of this ...
March 23, 2009

chemistry
The enzyme Y catalyzes the elementary reaction AB-->A + B An enzyme concentration of 1.0M Y can convert a maximum of 0.5M AB to the products A and B per second. What will happen when each of the following is added to a solution that contains 1.0M Y and 0.8M AB? I have to ...
March 22, 2009

chem
A student placed 12.5 of glucose (C6H12O6) in a 100ml volumetric flask, added enough water to dissolve the glucose by swirling, then carefully added additional water until the calibration mark on the neck of the flask was reached. The flask was then shaken until the solution ...
March 12, 2009

chemistry
A student placed 12.5 of glucose () in a 100.- volumetric flask, added enough water to dissolve the glucose by swirling, then carefully added additional water until the calibration mark on the neck of the flask was reached. The flask was then shaken until the solution was ...
March 12, 2009

Computer science
If the last value of Period is less than the number of periods specified in the Parameters worksheet, increment the Period value by 1, otherwise blank the cell(i.e. ""). What does this mean in spreadsheer syntax for excel using the IF function
January 26, 2009

english
"context affects content" what does this mean
January 9, 2009

chem
i have to catogerize the list based on which is ionic, polar covalent, and nonpolar covalent 1.SI 2.HBr 3.HP 4.SO 5.BeF 6.BeCl 7.ScO
November 18, 2008

chem
What is the boiling point of water at an elevation of 1.55×10^4 ft ? The atmospheric pressure at sea level is 760mmHg . This pressure decreases by 19.8mmHg for every 1000-ft increase in elevation. The boiling point of water decreases 0.05 degrees celsius for every 1mmHg ...
November 18, 2008

chem
nvm i figured it out
November 18, 2008

chem
The normal boiling point of water is 100.00 degrees celsius and the enthalpy of vaporization at this temperature is 40.657kj/mol. What would be the boiling point of water if it were based on a pressure of 1 bar instead of the standard atm?
November 18, 2008

chem
What is the longest wavelength of light that will provide photons of sufficient energy to break the pi bond and cause the isomerization? Energy required to break pi bond is 4.42*10^-19. wavelenght=c/f but how do i figure out what f is?
November 12, 2008

chem
What is the longest wavelength of light that will provide photons of sufficient energy to break the pi bond and cause the isomerization? Energy required to break pi bond is 4.42*10^-19. wavelenght=c/f but how do i figure out what f is?
November 12, 2008

chem
NVM FIGURED IT OUT
November 12, 2008

chem
Use bond energies to estimate the enthalpy change for the following reaction C2H2 + H2-> C2H4 i figured the bonds broken are: 1 C triple bond C 1(812kj/mol) 2 C-H 2(414kj/mol) 1 H-H 1(435kj/mol) Bonds formed 1 C=C 1(590kj/mol) 4 C-H 4(435kj/mol) Is this right
November 12, 2008

chem
The average bond enthalpy for a C=C double bond is 614kj/mol and that of a C-C single bond is 348kj/mol . Estimate the energy needed to break the pi bond in 2-butene. CH3 CH3 CH3 H \ / \ / C=C ------> C=C / \ / \ H H H CH3 Cis-2-butene Trans-2-butene
November 12, 2008

Chem
thx
November 12, 2008

Chem
Draw the electron-dot structure for CHClO.
November 12, 2008

chem
a compound containing only boron, nitrogen and hydrogen was found to be 40.3% B, 52.2%N, and 7.5% H by mass. If 3.301g of this compound is dissolved in 50.00g of benzene, the solution produced freezes at 1.30 degrees celsius. If Kf(freezing point depression constant) for ...
November 8, 2008

chem
a compound containing only boron, nitrogen and hydrogen was found to be 40.3% B, 52.2%N, and 7.5% H by mass. If 3.301g of this compound is dissolved in 50.00g of benzene, the solution produced freezes at 1.30 degrees celsius. If Kf(freezing point depression constant) for ...
November 7, 2008

chemistry
a mixture is prepared using equal masses of two volatile liquid benzene, C6H6 and ethanol C2H5OH. what is the mole fraction of benzene in this mixture?
October 26, 2008

chem
What electron transition in a hydrogen atom, starting from the orbit 10, will produce infrared light of wavelength 3040 ?
October 26, 2008

chem
How much energy, in joules, must be absorbed to convert to Na all the atoms present in 1.00mg of gaseous Na? The first ionization energy of Na is 495.8kj/mol .
October 26, 2008

chemistry
Zinc dissolves in acid according to the balanced equation. Zn(s)+ 2H(aq)-> Zn(aq) + H2(g) a sample of zinc is placed in a ice calorimeter. If 0.0657g of zinc causes a decrease of 0.109ml in the ice/water volume of the calorimeter, what is the enthalpy change, per mole of ...
October 22, 2008

chem
Zinc dissolves in acid according to the balanced equation. Zn(s)+ 2H(aq)-> Zn(aq) + H2(g) a sample of zinc is placed in a ice calorimeter. If 0.0657g of zinc causes a decrease of 0.109ml in the ice/water volume of the calorimeter, what is the enthalpy change, per mole of ...
October 20, 2008

chem
Zinc dissolves in acid according to the balanced equation. Zn(s)+ 2H(aq)-> Zn(aq) + H2(g) a sample of zinc is placed in a ice calorimeter. If 0.0657g of zinc causes a decrease of 0.109ml in the ice/water volume of the calorimeter, what is the enthalpy change, per mole of ...
October 18, 2008

chem
A calorimeter contains 16.0ml of water at 15.0degrees celsius. When 1.60g of X(a substance with a molar mass of 46.0g/mol) is added, it dissolves via the reaction X(s)+H20(l)->X(aq) and the temperature of the solution increases to 25.0degrees celsius. Calculate the enthalpy...
October 8, 2008

chem
The complete combustion of butane, (g) is represented by the equation C4H10+13/2O2->4CO2+5H20 STANDARD ENTHALPY IS -2877KJ/MOL How much heat, in kilojoules, is evolved in the complete combustion of 12.8L C4H10 at 23.8degrees celsius and 744mmhg ?
October 8, 2008

chem
The complete combustion of butane, (g) is represented by the equation C4H10+ 13/2O2->4CO2+5H2O standard enthalpy is -2877kj How much heat, in kilojoules, is evolved in the complete combustion of 12.8ml at 23.8degrees celsius and 744mmhg ?
October 8, 2008

chem
Calculate the standard enthalpy change for the reaction 2A+B->2C+D Use the following data: Substance A=-257kj/mol B=-413kj/mol C=189kj/mol D=-475kj/mol For the reaction given , how much heat is absorbed when 3.00mol of A react?
October 8, 2008

chem
The combustion of hydrogen–oxygen mixtures is used to produce very high temperatures (approximately 2500 °C) needed for certain types of welding operations. Consider the reaction to be H2(g) + 1/2O2(g) --> H20(l) Standard enthalpy is -241.8kj What is the quantity ...
October 3, 2008

chem
Helium-oxygen mixtures are used by divers to avoid the bends and are used in medicine to treat some respiratory ailments. What percent (by moles)of He(g) is present in a helium-oxygen mixture having a density of 0.538g/L at 25celsius and 721mmHg ? Responses chemistry - ...
September 26, 2008

chemistry
wat do u mean by change density to stp
September 26, 2008

chemistry
Helium-oxygen mixtures are used by divers to avoid the bends and are used in medicine to treat some respiratory ailments. What percent (by moles)of He(g) is present in a helium-oxygen mixture having a density of 0.538g/L at 25celsius and 721mmHg ?
September 26, 2008

chemistry
A 2.34L container of H2(g)at 752mmHg and 24 degrees is connected to a 3.17L container of He(g) at 717mmHg and 24 degrees. After mixing, what is the total gas pressure, in millimeters of mercury, with the temperature remaining at 24 degrees?
September 26, 2008

chemistry
A gaseous mixture of O2 and N2 contains 32.8% nitrogen by mass How do i figure out wat the mass is?
September 20, 2008

chemistry
Determine the number of moles of a) N atoms in a sample of C7H5(NO2)3 that has the same number of O atoms as 12.6g C6H12O6 Someone posted a way to answer this question but i still don't understand
September 20, 2008

chemistry
Determine the number of moles of N atoms in a sample of C7H5(NO2)3 that has the same number of O atoms as 12.6g C6H12O6
September 20, 2008

chemistry
still confused
September 19, 2008

chemistry
To determine the approximate mass of a small spherical shot of copper, the following experiment is performed. When 140 pieces of the shot are counted out and added to 8.6ml of water in a graduated cylinder, the total volume becomes 8.8ml . The density of copper is 8.92g/cm3. ...
September 19, 2008

chemistry
i dont get what u mean
September 19, 2008

chemistry
Determine the number of moles of a) N atoms in 42.5g of Mg(NO3)2 b) N atoms in a sample of C7H5(NO2)3 that has the same number of O atoms as 12.6g C6H12O6
September 19, 2008

algebra II, Functions, Ratios, Proportions, and Lo
Please help me with this questions, i tried doing it by myself but they are too hard. so pleasssssssssssssssssssssssssssssssssseeee help me. 1. Shown here is the graph of which of the following equations? A. y = –x – 3 C. y = x – 3 B. y = 3 – x D. y = x + 3...
June 22, 2007

Algebra II --- Variation, Progression, and theorem
1. If y varies inversely as x, and y = 12 when x = 6, what is K, the variation constant? A. 1⁄3 C. 72 B. 2 D. 144 2. Use the remainder theorem and the factor theorem to determine whether (y – 3) is a factor of (y4 + 2y2 – 4). A. The remainder is 0 and, ...
June 22, 2007

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