# Posts by Mima

Total # Posts: 38

science
A stone is allowed to fall from the top of a tower 100 m high and at the same time another stone is thrown vertically upwards with a velocity of 25 m/s. When and where will the two stones cross each other?

Physics
A 80.0 Hz generator with an rms voltage of 150 V is connected in series to a 3.20 k ohm resistor and a 3.50 micro farad capacitor. Find the phase angle between the current and the voltage.

physics
a block of mass m=0.9 kg is connected to a spring of force constant k= 775 N/m on a smooth horizontal surface. plot the potential energy of the spring from x= -5 cm to x= 5 cm. determine the turning points of the block if its speed at x= 0 is 1.2 m/s.

physics
A soccer ball is kicked from the ground with an initial speed of 14.5 m/s. After 0.272 seconds, ts speed is 12.4 m/s. (A) Give a strategy that will allow you to calculate the ball's initial direction of motion. (B) Use your strategy to find the initial direction.

Chemistry
Neat pure ethanol C2H5OH has an enthalpy of vaporization of 39.3 Kj/mol, and a vapor pressure of 0.308 atm at 50 C. What is the boiling point, at atmospheric pressure of 1 atm, of a solution consisting of 35 G of phenol (a non-electrolyte hydrocarbon with a molecular formula ...

Chemistry
Got it, you are right, it's 0.439. Thank you so much, I was doing an easy math mistake (substracting before multiplying). Thanks again.

Chemistry
E= 0.438? I got the same answer (1.987) when I used the numbers you mentioned. Is the E standard potential = -0.26 -(-0.76)? Am I doing that right?(its cathode-Anode) right?

Chemistry
Calculate the cell potential for the following reaction as written at 79C given that [Zn^+2] = 0.819 M and [Ni^+2] = 0.014 M. Zn + Ni^+2 = Zn^+2 + Ni I know: E=E -RT/nF ln Q reduction potential for Ni= -0.26 reduction potential for Zn = -0.76 so E standard potential = 0.5 E= 0...

chemistry
I'm getting 8.355E-22 Kg on for reactants, and 8.322E-22 Kg for products. I multiplied each mass they gave us in amu by 1.661E-27 to get it in Kg.

chemistry
For the following fusion reaction, Calculate change in energy per mole.( Answer in J/mole) 2H1 + 2H1 ---> 3H1 + 1H1 (the mass number is in front of the atom and the atomic number is behind the atom) Given info:Atoms with their masses(amu) H-1 1.00782 H-2 2.01410 H-3 3.01605...

Chemistry
Thanks, I got it right.

Chemistry
The hint they gave us now is that this is a first intigrated order reaction, I do not get it, what the order of the reaction has to do with nuclear chemistry and decay?

Chemistry
I thought about that, but didn't know the initial and remaining N. Why initial N is 100?

Chemistry
A fossil is found to have a C-14 level of 86% compared to living organisms. How old is the fossil?, (the half life of C14 is 5730 years).

Chemistry
Thank you so much.

Chemistry
carbon 14 has a half life of 5715 years. If you start with a 5 gram sample of 14C, what mass is left after 15,000 years?

chemistry
Spectrophotometer. 2 ml of NH3 is added to Cu(NO3)2 to give it dark blue color. If we accidantely put 3 ml of NH3, would the absorbance reading by spec should be considered? Explain. I wrote we shouldn't consider the reading because it will give darker color than it should...

chemistry
Why the addition of NH3 should be precise in spectrophotometer reading? What if it gives darker color?

Chemistry

Chemistry
Our professor just told us that the final exam will be the ACS exam, we are taking general Chemistry II. What is the best way to study for ir? Is the preparing for ACS general chemistry study guide good? If we are taking general Chemistry II do we have to study Chemistry I again?

Chemistry
Our professor just told us that the final exam will be the ACS exam, we are taking general Chemistry II. What is the best way to study for ir? Is the preparing for ACS general chemistry study guide good? If we are taking general Chemistry II do we have to study Chemistry I again?

Chemistry
In the lab, as acid concentration got decreased, the Ka got increased. Why ?

chemistry
Thanks, you mean finding n for acid or base? The graph represent only PH and volume we added for acid or base in ml.

chemistry
We had a Chemistry lab for buffer system, we used HCl and NAOH. We did a graph ( PH vs ml of HCL and NaOH, we told to estimate the buffer capacity using the graph. How to do this?

math
the sum of the digits of a two digit prime number is substracted from the number. prove that the difference cannot be a prime number.

math
when jason arranges his toy soldiers in rows of 6, he has left 1.when he arrahges them in rows of 8, he has 3 left over. when he arrenges in rowsof 10 then 5 left over. what is the smallest possible number of toy soldiers that jason plays with/

chemistry
Thanks a lot, I got it.

chemistry
Thank you so much for replying, but I can't understand how to solve for partial pressure of CO2, when I get the [H^+] from PH then how to solve for partial pressure of CO2?

chemistry
carbon dioxide dissolves in water to form carbonic acid. Estimate the thermodynamic equilibrium constanst (K) for this reaction (delta Gf values: H2CO3= - 616.1, H2O= - 237.1, CO2= - 394.4) . Carbonic acid then ionizes in water (Ka1= 4.5 x 10^-7). Ignoring Ka2, estimate (K) ...

Chemistry
A- a water soluble salt forms a precipitant during Group 3 analysis. An acidic solution of this precipitant and NaBiO3 yields a pinkish color. This same salt has no reaction to concentrated H2SO4 or AgNO3, what is the chemical formula for this salt? B- a brown colored salt ...

Chemistry
A- a water soluble salt forms a precipitant during Group 3 analysis. An acidic solution of this precipitant and NaBiO3 yields a pinkish color. This same salt has no reaction to concentrated H2SO4 or AgNO3, what is the chemical formula for this salt? B- a brown colored salt ...

Chemistry
You are right, thank you so so much. With addition of HCl, the Ph= -0.052. With addition of NAOH, the PH= 0.052. Thank you for all your efforts.

Chemistry
I got initial PH= 9.24 PH after HCl addition= 9.19 PH after NaOH addition= 9.3 so delta PH after HCl= 0.05 delta PH after NaOH= - 0.06 all these still wrong answers. could it be that I'm calculating the total volume wrong? should be 0.01+0.006 L?

Chemistry