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May 1, 2016

# Posts by eng

Total # Posts: 122

science
if i use 30 ul from a total volume of 600ul to get 40ug/ml. So to get the total ug only, do i take 40ug/ml*.030ml*(600ul/30ul)=total ug
May 12, 2012

science
if i use 30 ul from a total volume of 600ul to get 40ug/ml. So to get the total ug only, do i take 40ug/ml*.030ml*(600ul/30ul)=total ug
May 12, 2012

electrical engineering
Input range: -100mV to +60mV Voltage supplies to the op-amp= ±15V how do we find the input offset voltage?
February 3, 2012

physics
how do i calculate the pressure of a pipe with same area and constant velocity. I tried to use bernoulli's equation but it only applies if the area of the opening and end are not the same
October 7, 2011

biology
are both ER and secretory vesicles have double bilayer membrane
January 5, 2011

math
for this infinite series (-1)^n/n^2 if i use alternating series test to show that sequence does of a^n does not go to 0, then does this mean that this series is diverging
July 27, 2010

math
how do i represent 1/(1+x^4) in general taylor polynomial. I know the pattern is 1-x^4+x^8-x^16..... I dont know how to represent this pattern in variables equation form. What i mean by general taylor polynomail is for example 1/(1-x)=1+x+x^2+x^3...+x^n. What is need is after...
July 20, 2010

math
how do i represent 1/(1+x^4) in general taylor polynomial. I know the pattern is 1-x^4+x^8-x^16..... I dont know how to represent this pattern in variables equation form
July 19, 2010

math
how do i represent 1/(1+x^4) in general taylor polynomial. I know the pattern is 1-x^4+x^8-x^16..... I dont know how to represent this pattern in variables equation form
July 19, 2010

math
how is this series 3+ 9/4 +27/16 +81/64... is converge to 12? i represent the series as 3^(n+1)/4^n n starts from 0 to infinity, is this correct formula
July 16, 2010

math
for a strict triangular form, does it has to be in I matrice or just the main diagonal entries are all 1]\
July 1, 2010

math
in a skew symmetric, how do we explain that its diagonal entries has to be all 0 without giving examples to support it
June 30, 2010

engineering
what is the device used called for eye laser surgery and do you know which company use it
June 23, 2010

engineering
what is the device called for eye laser surgery and do you know which company use it
June 23, 2010

chemistry
CoSO4 + KI + KIO3 + H2O  Co(OH)2 + K2SO4 + I2 2KI yield I2 + 2e 2KIO2 10e yield I2 are there 10 electrons being transferred or just 5 only
June 6, 2010

chemistry
HCl (aq) + Cu (s) + HNO3 (aq) yield CuCl2 (aq) + NO (g) + H2O (l) do i say that HNO3 is oxidizing agent or just N+5 is the oxidizing agent
June 6, 2010

chemistry
can you what is G and G knot in terms of spontaneity and chemical equilibrium. I know that G is spontaneous when is negative but what does G knot tell you
June 4, 2010

chemistry
because it gives 1893.5g, it threw me off. I wasnt sure if it was there to trick me
June 4, 2010

chemistry
The electrochemical cell described by the cell notation has a standard cell potential of -0.35 V. Calculate the Wmax (kJ) the cell has done if 1893.5 g of MnO42-(aq) (Molar Mass - 118.94 g/mol) forms. Round your answer to 3 significant figures. Pt(s) | Hg22+(aq), Hg2+(aq)||...
June 4, 2010

chemistry(check my steps)
The electrochemical cell described by the cell notation has a standard cell potential of -0.35 V. Calculate the Wmax (kJ) the cell has done if 1893.5 g of MnO42-(aq) (Molar Mass - 118.94 g/mol) forms. Round your answer to 3 significant figures. Pt(s) | Hg22+(aq), Hg2+(aq)||...
June 3, 2010

chemistry
A balanced equation that represents an overall cell reaction is shown. Choose the cell notation which corresponds to the electrochemical cell that is described by this equation. 2H2O(l) → 2H2(g) + O2(g) i dont get why the answer is this. How can OH- appear in both sides ...
June 3, 2010

chemistry
oops, the second one should be Pt(s) | Mn2+(aq) | MnO2(s) | H+(aq) || H+(aq) | PbO2(s) | Pb2+(aq) | Pt(s) but can you clarify the comma one
June 3, 2010

chemistry
Pt(s) | Mn2+(aq), MnO4-(aq), H+(aq) || H+(aq), IO3-(aq) | I2(s) | Pt(s) Pt(s) | Mn2+(aq) | MnO2(s) | H+(aq) || H+(aq) || PbO2(s) | Pb2+(aq) | Pt(s) how come the first one has comas within cell notation but not the second one,
June 3, 2010

chemistry
i see thanks, this helps alot, so do i say tht H2O2 is the reducing agent and ClO2 is the oxidizing agent or just oxygen and chlorin only
June 3, 2010

chemistry
for the reaction, determine the number of transferring electrons so then i can pug into G=-nFE I'm assigning charges to each of the elements H2O2(aq) + 2ClO2(g) → O2(g) + 2HClO2(aq) (+1,-1) + (+4,-2) (0) (+1,+1,-2) since O changes from -1 to 0, so it lost one ...
June 3, 2010

chemistry
how do i write this reaction in cell notation I2(s) + 2MnO4-(aq) + 4H+(aq) → 2IO3-(aq) + 2Mn2+(aq) + 2H2O(l)
June 1, 2010

physics
if the system is a basket, the basket is tied to a rope and it is stopped by a fixed clamp when it is falling down, I know there is initial KE but how come initial work is negative. Isnt force and displacement are in the same direction, so work should be positive?
May 25, 2010

physics
for both of these object system1: earth and ball if a ball is falling down, is the work done on it positive since force and displacement are in the same direction. system 2: earth and basket a basket is tied to a rope and is dropped then come to a full stop, then is the work ...
May 25, 2010

chemistry
do we have buffering region and ph=pka in any of these conditions: strong base vs strong acid strong base vs weak acid weak base vs strong acid weak base vs weak acid
May 23, 2010

chemistry
when do we have pka=ph
May 23, 2010

chemistry
Which of the following rate laws suggests that the reaction probably occurs in a single step? why is this problem cant be answer a since it has order of 1 a)(CH3)3CBr + OH- →(CH3)3COH + Br- rate = k[(CH3)3CBr] b)NO(g) + O2(g) → NO2(g) + O(g) rate = k[NO][O2] c)H2O2...
May 18, 2010

chemistry
Which of the following rate laws suggests that the reaction probably occurs in a single step? why is this problem cant be answer a since it has order of 1 a)(CH3)3CBr + OH- →(CH3)3COH + Br- rate = k[(CH3)3CBr] b)NO(g) + O2(g) → NO2(g) + O(g) rate = k[NO][O2] c)H2O2...
May 17, 2010

chemistry
A 50-mL Mohr buret is connected to a 1-ft length of capillary tubing. The buret is then filled with water and the volume of water versus time is monitored as the water gradually flows through the capillary tubing. This process is found to be first-order with a rate constant of...
May 16, 2010

chemistry
Which equation describes the relationship between the rates at which Cl2 and F2 are consumed in the following reaction? Cl2(g) + 3F2(g) yield 2ClF3(g) a)-d(Cl2)/dt = -d(F2)/dt b)-d(Cl2)/dt = 2[-d(F2)/dt] c)3[-d(Cl2)/dt] = -d(F2)/dt d)2[-d(Cl2)/dt] = -d(F2)/dt e)-d(Cl2)/dt = 3...
May 14, 2010

Which of the following will be affected by the addition of a catalyst to a chemical reaction? a)the value of the reverse rate constant, kr b)the magnitude of the equilibrium constant c)the value of the forward rate d)ΔHo e)the value of the forward rate constant, kf f)&#...
May 14, 2010

Which equation describes the relationship between the rates at which Cl2 and F2 are consumed in the following reaction? Cl2(g) + 3F2(g) yield 2ClF3(g) a)-d(Cl2)/dt = -d(F2)/dt b)-d(Cl2)/dt = 2[-d(F2)/dt] c)3[-d(Cl2)/dt] = -d(F2)/dt d)2[-d(Cl2)/dt] = -d(F2)/dt e)-d(Cl2)/dt = 3...
May 14, 2010

Which equation describes the relationship between the rates at which Cl2 and F2 are consumed in the following reaction? a)-d(Cl2)/dt = -d(F2)/dt b)-d(Cl2)/dt = 2[-d(F2)/dt] c)3[-d(Cl2)/dt] = -d(F2)/dt d)2[-d(Cl2)/dt] = -d(F2)/dt e)-d(Cl2)/dt = 3[-d(F2)/dt] is it e
May 13, 2010

chemistry
what does it mean by in phase and out of phase for orbitals. Is in phase means that it's bonding and out of phase is antibonding?
May 12, 2010

physics
in an adiabatic process from A to B, do A and B have same temperature?
May 3, 2010

so do i put the answer as C(s) including the state
April 30, 2010

For the cell: C(s) C+(aq) B+(aq) B(s). Metal ______ is the "negative" electrode. is it C(s)
April 30, 2010

From the Standard Potential Table in your general chemistry textbook: Which reaction has been chosen as the 'standard' against which every other reaction is measured? A. 2H+ + 2e–H2 B. Li+ + e–Li C. O2 + 4H+ + 4e–2H2O D. F2 + 2e–2F– E. H2 + 2e...
April 29, 2010

math
how do you take log(-63)
April 28, 2010

calculus
when finding area, what does it mean when it says that the function is below by the x-axis, can you give me example of this
April 27, 2010

chemistry
Wich of the following is NOT true about the blank for the experiment, 'Analysis of a Complex Iron Salt'? A. A blank is titrated to correct for any reactive impurities in the solvent. For this experiment, the impurities would be reducing agents that would react with ...
April 17, 2010

chemistry(check my asnwer)
Why doesn't potassium ion K+ from KMnO4 appear in the following two unbalanced equations: MnO4– + C2O42– Mn2+ + CO2 MnO4– + Fe2+ Mn2+ + Fe3+ ? A. KMnO4 is not added to either reaction. B. The presence of K+ would result in a net positive charge in the ...
April 17, 2010

chemistry(check my work)
Which of the following is NOT true of colligative properties? Colligative properties are... A. dependent on the mass of solute present. B. independent of the chemical identity of the solute. C. dependent on the molar mass of the solute. D. responsible for lowering the vapor ...
April 6, 2010

chemistry(check my work)
The freezing point of a solution is A. lower than the freezing point of the solvent alone because higher temperature is required to accelerate solvent molecular motion enough to overcome obstructon by solute particles.. B. higher than the freezing point of the solvent alone ...
April 6, 2010

chemistry(check my explanation)
sorry to repost this question but i'm confused on this part The solubility of borax is directly proportional to temperature. Therefore, the sign of H is A. negative B. positive C. unknown with the given information like you said earlier, borax dissolves when heat is added...
April 5, 2010

chemistry(check my work on anothe rproblem)
When a reaction mixture with a total volume of 1390 mL that is 0.00791 M aqueous Ba2+ was stoichiometrically produced as per the balanced equation, what mass (g) of Ba2+ was required? Ba(OH)2(aq) + 2 HClO4(aq) → Ba(ClO4)2(aq) + 2 H2O(l) .00791x1.39=mole of Ba2+ mole of ...
April 3, 2010

If 0.836 g of solid Al reacts stoichiometrically according to the balanced equation in a reaction solution with a total volume of 1160 mL, what mass (g) of gaseous H2 is produced? 6 HClO4(aq) + 2 Al(s) → 3 H2(g) + 2 Al(ClO4)3(aq) 0.836g/molecular weight Al=mole of Al ...
April 3, 2010

chemistry
If 0.755 g of Al3+ dissolved in 960 mL of water reacts stoichiometrically according to the balanced equation, what volume (mL) of 0.0875 M aqueous Cl- is required? Al2(SO4)3(aq) + 3 BaCl2(aq) → 2 AlCl3(aq) + 3 BaSO4(s)
April 3, 2010

chemistry(check my work)
If 6.01 g of K2SO3 dissolved in 930 mL of water reacts stoichiometrically according to the balanced equation in a reaction solution with a total volume of 990 mL, what is the molarity (M) of KCl produced? K2SO3(aq) + 2 HCl(aq) → SO2(g) + 2KCl(aq) + H2O(l) 6.01gx ...
April 3, 2010

chemistry(check my work)
how would you do it differently then
April 2, 2010

chemistry(check my work)
When a reaction mixture with a total volume of 1720 mL that contains 0.605 L of gaseous CO2 measured at STP dissolved in 940 mL of water was stoichiometrically produced as per the balanced equation, how many mol of solid CaCO3 were required? H2SO4(aq) + CaCO3(s) → CO2(g...
April 2, 2010

chemistry
When a reaction mixture with a total volume of 1750 mL that is 0.0263 M aqueous K+ was stoichiometrically produced as per the balanced equation, what volume (mL) of 0.0326 M aqueous K3PO4 was required? 3 BaBr2(aq) + 2 K3PO4(aq) → Ba3(PO4)2(s) + 6 KBr(aq)
April 2, 2010

chemistry
i did 0.049x2/3=mole of CuCl2 then mole of cucl2/.99 then times by 2 to get 0.0660 but its wrong, the actual answer is 0.148. Can you double check this again why i did it wrong
April 2, 2010

chemistry
If 0.0490 mol of solid Al reacts stoichiometrically according to the balanced equation with 990 mL of aqueous Cl-, what molarity (M) of Cl- is required? 3 CuCl2(aq) + 2 Al(s) → 3 Cu + 2AlCl3(aq)
April 2, 2010

chemistry
since heat is added, so does that mean H is positive(endothermic)
March 29, 2010

chemistry
please check my answer(one with star). The solubility of borax is directly proportional to temperature. Therefore, the sign of H is A. negative* B. positive C. unknown with the given information since solubility shifts the reaction to the right, therefore it is exothermic so H...
March 29, 2010

chemistry
A 1.00 L volume of 0.609 M HNO3 is condensed to a volume of 0.750 L, calculate the molarity (M) of H+ in the new solution
March 28, 2010

chemistry
Does the basicity decreases as going down the column and right across the periodic table? How does the size of an element or electronegativity apply to strength of basicity and acidicity?
March 23, 2010

chemistry
is Li3As a semiconductor
March 14, 2010

chemistry
did i order the intermolecular forces correctly ion-ion > ion-dipole force > dipole-dipole >ion-induced dipole> dipole-induced dipole> hydrogen bond>dispersion bond
March 14, 2010

chemistry
Why is HF has lower boiling point than CsI, even though HF has hydrogen bond. Does HF have higher boiling point than O2
March 13, 2010

chemistry
by the way, how can you tell if work is 0 for 2 mol of solid iron (C = 25:1 J/(molK)) is heated from 20C to 200C. How much does its internal energy change?
March 11, 2010

chemistry
i see, thank you for clarifying
March 10, 2010

chemistry
lets just say that 5g of solid benzoic acid burns under gaseous oxygen atmoshphere. Temperature increases from 20c to 50c. So is this exothermic so the sign is negative? how is it not the same as 2 mol of solid iron (C = 25.1 J/(mol K)) is heated from 20C to 200C(endothermic) ...
March 10, 2010

chemistry
lets just say that 5g of solid benzoic acid burns under gaseous oxygen atmoshphere. Temperature increases from 20c to 50c. So is this exothermic so the sign is negative? how is it not the same as above question
March 9, 2010

chemistry
2 mol of solid iron (C = 25.1 J/(mol K)) is heated from 20C to 200C. How much does its internal energy change? U = q +W but no matter exchange so work is 0. then U=q=9036J But why is q not negative since isnt the system loses its heat to the surrounding
March 9, 2010

physics
if velocity vector is changing but speed is constant, can there still be work
March 5, 2010

physics
if a particle has work of 8J and doubles its speed. how much work it has done? Can we still determine work in this problem without mass
March 4, 2010

calculus
why is lim of tanx as x approaches to (pie/2)+ is negative infinity. Shouldnt it be positive infinity since pie/2 is approaching on the right
February 28, 2010

chemistry
Gaseous carbon monoxide reacts according to the balanced equation. If a total of 1040 kJ of heat is generated in the reaction as written, how many grams of CO2 are produced? enthalpy=-566kJ 2 CO(g) + O2(g) → 2 CO2(g)
February 25, 2010

chemistry
Liquid quinoline reacts according to the balanced equation. When 1200 g of C9H7N is reacted, calculate the sign and magnitude (kJ) of the heat produced. 4 C9H7N(l) + 43 O2(g) → 2 N2(g) + 36 CO2(g) + 14 H2O(l) .
February 23, 2010

chemistry
is CaO soluble
February 22, 2010

chemistry
what if compound has those metalloids(metal near stair case) with gas element, is it going to be semiconductor. Can you think of any other compound with metalloid and gas elements beside SiO2 that is insulator
February 21, 2010

chemistry
1)RuO2 is molecular, but why is it insulator even though Ru is metal? 2)Why is TiO ionic? I thought only group 1 and 2 would make ionic compound 3)If the the compound has metal and metalloid like GaAs, is it always semiconductor
February 21, 2010

chemistry
1) Calculate the specific heat capacity (J/g oC) of iron, if a 803 g sample lost 937.4 J of heat energy in going from an initial temperature of 5.50 oC to a final temperature of 2.90 oC. 2)Calculate the final temperature (oC) of a 243 g sample of water originally at a ...
February 17, 2010

chemistry
for NaTl, is the unit cell of it based on the repetition of body centered cubic and the holes in this unit cell are octahedral?
February 16, 2010

chemistry
for NaTl, is the unit cell of it based on the repetition of body centered cubic and the holes in this unit cell are octahedral? how many of each of the 2 cubes drawn for NaTl are required its unit cell? is it 8?
February 15, 2010

chemistry
this is what i did: q=200x389x4.184 then q/0.949g x56.08g/1mol but i still got the wrong answer
February 15, 2010

chemistry
nvm i figure out how to do it already
February 13, 2010

chemistry
If 600 mL of 1.05 M aqueous CaCl2 and 720 mL of 0.792 M aqueous Na3PO4 are reacted stoichiometrically according to the balanced equation, how many milliliters of 0.792 M aqueous Na3PO4 remain? Round your answer to 3 significant figures.
February 13, 2010

chemistry
Based on the balanced equation 2Ba + O2 → 2BaO calculate the number of BaO formula units formed when 142 Ba atoms and 73 O2 molecules react?
February 12, 2010

chemistry
nvm i figure out how to do this kind of problem but can u help me with my other question
February 12, 2010

chemistry
Based on the balanced equation 2Al + 6HCl → 2AlCl3 + 3H2 calculate the number of excess reagent units remaining when 140 Al atoms and 402 HCl molecules react?
February 12, 2010

chemistry
can anyone help me with this
February 10, 2010

chemistry
Based on the balanced equation 2I2O5 + 10NO → 5N2O4 + 2I2 calculate the number of excess reagent units remaining when 188 I2O5 molecules and 850 NO molecules react? do i start with a new balance equation in order to solve it
February 10, 2010

chemistry
Based on the balanced equation, 10Li + N2F4 → 4LiF + 2Li3N calculate the formula units of LiF formed when 54 molecules of N2F4 are reacted. since one mole of N2F4 yields 4LiF, then 54N2F4 yields 216LiF, am i correct
February 10, 2010

Physics
Yes! Thank You! I was very close but I messed up on my derivative somehow :)
February 7, 2010

Physics
A potential energy function for a two-dimensional force is of the form U = 3 x^(4)y - 8 x. Find the force that acts at the point (x, y). (Use x and y as appropriate.) I know its something about partial derivatives but I'm not sure how to go about it. And the answer has to ...
February 7, 2010

chemistry
it says to write an unbalanced chemical equation that summarizes the statement
February 6, 2010

chemistry
i got number 2 already, just help me with number 1
February 6, 2010

chemistry
1)gaseous sulfur trioxide and gaseous nitrogen monoxide form when gaseous sulfur dioxide and gaseous nitrogen dioxide react. 2)Enter the formula of the missing substance ( Y ) in the balanced equation below. Do not give the coefficient. C2H4 + 3Y → 2CO2 + 2H2O
February 6, 2010

chemistry
If 1373 g of a substance is dissolved in 2315 g of cyclohexane solvent, the boiling point of the solution is 87.69 oC. Calculate the apparent molar mass (g/mol) of substance.
January 31, 2010

chemistry
If 1373 g of a substance is dissolved in 2315 g of cyclohexane solvent, the boiling point of the solution is 87.69 oC. Calculate the apparent molar mass (g/mol) of substance.
January 31, 2010

chemistry
Transfer the tablet to a clean 125-mL Erlenmeyer flask. Add 10-mL of 1M NaOH and heat the mixture to a gentle boil. Once the solution has cooled to room temperature, transfer it to a 100-mL vol. flask. Using the diluted solution from the 100-mL volumetric flask, rinse a 1-mL ...
January 31, 2010

chemistry
A 4.14 m solution of the solute methylene chloride dissolved in the solvent ethanol is available. Calculate the mass ( kg ) of the solution that must be taken to obtain 1487 g of methylene chloride. CH2Cl2-1327 (kg/m^3) C2H5OH-789.3 (kg/m^3)
January 28, 2010

chemistry
If 6.38 g of a polyethylene glycol is dissolved in 7550 ml of water at 300 oK, the solution has an osmotic pressure of 0.171 torr. Calculate the molar mass (g/mol) of the polyethylene glycol.
January 28, 2010

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