Sarah H

Most popular questions and responses by Sarah H
1. Gen Chem

Neptunium-239 has a half-life of 2.35 days. How many days must elapse for a sample of 239-Np to decay to 1.00% of its original quantity? I got: close to 15 days. Is this right? I figured that about 1% of the original quantity would be roughly 6.5 Half

Determine the mass of carbon monoxide that is produced when 45.6 g of methane CH4 react with 73.2 g of oxygen gas, O2. The products are CO and H2O. Please check my work: CH4 + 3O2 ---> 2CO + 2H20 nCH4=2.84 mol nO2=4.58 mol Limiting Reactant: 1 mol CH4/2.84

3. Gen Chem

Chromium can be electroplated from an aqueous solution containing sulfuric acid and chromic acid, H2CrO4. What current is required to deposit chromium at a rate of 1.25 g/min? 1mol H2CrO4 has 51.996 grams current= coulomb/sec How do I convert to get

4. Chem -plz check work

so i've worked on this some more, now I am asking if someone will plz check my work 2 half cells in a galvanic cell consist of one iron Fe(s) electorde in a solution of iron (II) sulphate FeSO4(aq)and a silver Ag(s) electrode in a silver nitrate solution,

5. Gen Chem

A liquid is heated from 33.96°C to 104.32°C. The vapor pressure increases from 23.54torr to 984.35torr. What is the heat of vaporization of the liquid in kJ/mol? The change in temperature is 70.36°C. Change in vapor pressure = 960.76 torr. What is the

6. Gen Chem

Consider a cell based on the following reaction: GeO(s) + H2O(l) + 2 Ag+(aq) ===> GeO2(s) + 2 H+(aq) + 2 Ag(s) If [Ag+] = 1 M, at 25°C, would it be..... pH = 2 ( E° - E ) / 0.059159 V. or pH = ( E° - E ) / 0.059159 V.

7. Gen Chem

What is n, the number of moles of electrons transferred, in the following reaction? 2 MnO4-(aq) + 16 H+(aq) + 10 Cl-(aq) ===> 2 Mn2+(aq) + 5 Cl2(g) + 8 H2O(l).

I have no idea what I'm doing here, please help. 2 half cells in a galvanic cell consist of one iron Fe(s) electorde in a solution of iron (II) sulphate FeSO4(aq)and a silver Ag(s) electrode in a silver nitrate solution, a)state the oxidation half

Hi, please check my work: In an experiment, 23.4 g of FES are added to excess oxygen and 16.5 g of FE2O3 are produced. The balanced equation is: 4FeS + 7O2 --> 2Fe2O3 + 4SO2 Calculate the % yield. My Answer: nFeS=23.4g/87.92 g/mol =0.266 mol 4mol FeS /

10. gr. 12 chemistry

Hi, please check my work: In an experiment, 23.4 g of FES are added to excess oxygen and 16.5 g of FE2O3 are produced. The balanced equation is: 4FeS = 7O2 --> 2Fe2O3 + 2SO2 Calculate the % yield. My Answer: nFeS=23.4g/87.92 g/mol =0.266 mol 4mol FeS /

11. Gen Chem

Which provides the greatest increase in entropy for a mole of substance? a)Water melts at 0°C. b)Liquid water is heated from 0°C to 25°C. c)Gaseous water is converted to solid ice at 0.1°C. d)Water is converted from liquid to vapor at 100°C. e)Cannot

12. Gen Chem

The signs of DG, DH, and DS at 25°C are shown in the table below for three reactions. Reaction DG DH DS I - + + II - - + III - - - Which reaction or reactions should go in the REVERSE direction at high temperature?

13. Gen Chem

A current is passed through two cells connected in series. The half-reactions occurring at the cathode of each cell are TcO4-(aq) + 8 H+(aq) + 7 e- ===> Tc(s) + 4 H2O(l) and Cu2+(aq) + 2 e- ===> Cu(s). If 4.40 g of copper are deposited in the second cell,

14. Gen Chem

Which of the following conditions MUST be true for the entropy of a pure solid to be zero? a) T must be 0 K b) The solid must be crystalline and not amorphous c)the solid must be perfectly ordered d) the solid form must be an element

15. Chemistry - Bob Pursley

Posted by Sarah H on Friday, May 23, 2008 at 8:10pm. Hi, please check my work: In an experiment, 23.4 g of FES are added to excess oxygen and 16.5 g of FE2O3 are produced. The balanced equation is: 4FeS = 7O2 --> 2Fe2O3 + 2SO2 Calculate the % yield. My

Hi, please check my work: In an experiment, 23.4 g of FES are added to excess oxygen and 16.5 g of FE2O3 are produced. The balanced equation is: 4FeS = 7O2 --> 2Fe2O3 + 2SO2 Calculate the % yield. My Answer: nFeS=23.4g/87.92 g/mol =0.266 mol 4mol FeS /

17. Math

Line A passes the points (-5,-13) and (1,-1). Line B runs perpendicular to Line A and passes the points (6,5). Find the equation of each line.

Hi, please check my work: In an experiment, 23.4 g of FES are added to excess oxygen and 16.5 g of FE2O3 are produced. The balanced equation is: 4FeS = 7O2 --> 2Fe2O3 + 2SO2 Calculate the % yield. My Answer: nFeS=23.4g/87.92 g/mol =0.266 mol 4mol FeS /

19. chem

what is the common name for ethane and propene? I think propene is propylene but i don't know about ethane.

#1) how many atoms are represented by 2.0 mol of carbon? I think 12.01 x 10^23 #2) Calculate the # of atoms of each element present in 3.67 mol of H^2SO^4...I have no idea how to do this one?

21. Gen Chem

Consider the following reaction, A B in a 1.00L container. At 1.77°C, the molar concentrations of A and B, respectively, 5.838M and 3.945M. Suddenly, 8.744 moles of A are added to the system. What is the change in DG of the system? Give the answer in kJ?

22. Gen Chem

If Q=.61259, what is the formula to convert to pQ? Is it pQ=lnQ?

23. Gen Chem

n = 6 and E° = 0.011v for a redox reaction with Q = 7.03 x 10-1. Calculate E. Assume T = 298.15K. So I did E=E°-(RT/nF)lnQ Since the temp is 298.15, I substituted0.02569 for (RT/F) and got 0.011v-(0.0259/6)lnQ and got -.002355 Is that correct?

24. Gen Chem

Consider the following reaction, A B in a 1.00L container. At 1.77°C, the molar concentrations of A and B, respectively, 5.838M and 3.945M. Suddenly, 8.744 moles of A are added to the system. What is the change in DG of the system. Give the answer in kJ?

25. Gen Chem

n = 6 and E° = 0.011v for a redox reaction with Q = 7.03 x 10-1. Calculate E. Assume T = 298.15K. How do I set this equation up?

26. Gen Chem

What is the number of nucleons in 236-U2+?

27. Math

A linear function f(x) and its inverse f-1(x) intersect at the point (5,5). Create a function, f(x) that would satisfy this requirement

28. Math

A linear function f(x) and its inverse f-1(x) intersect at the point (5,5). Create a function, f(x) that would satisfy this requirement

1. Math

how did you get the slope of -1/ slope of A=-1/2?Is the slope of line a is 2?

posted on December 1, 2015
2. chem

I MEAN ETHYLENE GLYCOL, SORRY.

posted on May 24, 2008
3. chem

not ethelyne glycol?

posted on May 24, 2008
4. Gen Chem

That makes sense, just so I understand, how did you get 8.666 g Cr? What does the +6 to 0 mean?

posted on March 28, 2008
5. Gen Chem

How can I figure the equivalents of Cu deposited and then the number of coulombs?

posted on March 28, 2008
6. Gen Chem

so n=10 then, right? 2Mn atoms (2*5), and 1*10 for the Cl...?

posted on March 28, 2008
7. Gen Chem

So is n=5 then? (7-1)+(-1-0)? or (7-1)+(|-1-0|) then n=7? My choices are 2, 4, 5, 10, 16...

posted on March 28, 2008
8. Gen Chem

It can be more than one of these choices, its a "check all that apply" question. Are there any other options that must apply for S=0??

posted on March 28, 2008