# katherine

Most popular questions and responses by katherine
1. ## Chemistry

Using the following data calculate Delta Sfus and Delta Svap for K in J/mol-k Tm(K) = 336, Delta H Fus(kJ/mol) = 2.33, Tb (K) = 1033, Delta H vap (kJ/mol) = 77.1 For Delta S fus i'm supposed to use 336 K the Tm value and for Delta S vap i'm supposed to use

2. ## Chemistry

Under standard conditions (298 K and 1 atm), which statement is true? a] diamond converts to graphite spontaneously b] graphite converts to diamond spontaneously c] none of the above How can the spontaneity of the reaction be reversed? a] increase the

3. ## SS

How is the number of Electoral College seats per state determined? (1 point) by the number of party delegates assigned to the state by the total number of House and Senate representatives by the traditional number assigned under the 12th Amendment by

4. ## chemistry

Indicate the number of equivalents in each of the following: 4mol Mg2+ 0.1mol H+ 2mol Cl- 3mol Fe3+

5. ## Chemistry

The voltage generated by the zinc concentration cell described by, Zn(s)|Zn2+ (aq, 0.100 M)||Zn2+ (aq, ____ M)|Zn(s) is 24.0 mV at 25 °C. Calculate the concentration of the Zn2 (aq) ion at the cathode. Hi, I posted this question awhile back but I think it

6. ## Chemistry

For the reaction described by the chemical equation: 3C2H2(g) -> C6H6(l) .. Delta H rxn = -633.1 kJ/mol a) Calculate the value of Delta S rxn at 25.0 C... b) Calculate Delta G rxn... c) In which direction is the reaction, as written, spontaneous at 25 C

7. ## Chemistry

The Ksp of CaSO4 is 4.93× 10–5. Calculate the solubility (in g/L) of CaSO4(s) in 0.300 M Na2SO4(aq) at 25 °C

8. ## Chemistry

Calculate the concentrations of all species in a 0.810 M Na2SO3 (sodium sulfite) solution. The ionization constants for sulfurous acid are Ka1 = 1.4 x 10^-2 and Ka2 = 6.3 x 10^-8 so I'm trying to find Na, SO3 2-, HSO3-, H2SO3, OH-, H+ and heres what I

9. ## Chemistry

Consider two cells, the first with Al and Ag electrodes, and the second with Zn and Ni electrodes, each in appropriate 1.00M solutions of their ions. If 2.10g of metal is plated in the voltaic cell, how much metal is plated in the electrolytic cell?

10. ## Chemistry

A solution household bleach contains 5.25% NaClO, by mass. Assuming that the density of bleach is the same as water(1.0g/ml). Calculate the volume in mL of household bleach that should be diluted with water to make 500.0 ml of a pH= 9.80 solution. Here's

11. ## Chemistry

A 0.450-gram sample of impure CaCO3(s) is dissolved in 50.0 mL of 0.150 M HCl(aq). The equation for the reaction is: CaCO3(s)+2HCl(aq) -> CaCl2(aq) + H2O(l) + CO2(g) The excess HCl(aq) is titrated by 9.75 mL of 0.125 M NaOH(aq). Calculate the mass

12. ## Physics

A 4-kg sled sliding freely on an icy surface experiences a 2 _ N frictional force exerted by the ice and an air-resistive force of 0.5 N. a. What is the net force acting on the sled? b. What is the acceleration of the sled?

13. ## Chemistry

Calculate delta G of the reaction at 25 degrees C: 2Au^3+ (aq) + 3Ni(s) 2Au(s) + 3Ni^2+(aq) Au3+ + 3e- ==> Au Eo = +1.50V Ni2+ + 2e- ==> Ni Eo = -0.23 V 2Au3+ + 3Ni ==> 3Ni2+ + 2Au The answer is -1.00 x 10^3 kJ but i'm not getting that answer!!!!!!! please

14. ## Chemistry

Silver chromate is sparingly soluble in aqueous solutions. The Ksp of Ag2CrO4 is 1.12× 10–12. What is the solubility (in mol/L) of silver chromate in 1.4 M potassium chromate aqueous solution? In 1.4 M silver nitrate aqueous solution? In pure water?

15. ## Chemistry

A current of 5.18 A is pass through a Cr(NO3)2 solution for 1.20 hours. How much chromium is plated out of the solution? __g I have no idea how to approach this. Here's what I tried to do logically but I'm not sure if it works out: I know that the

16. ## math

a true or false test has 5 questions. what is the probability of guessing exactly four out of the five answers correstly.

17. ## chemistry

Calculate the cell potential for the following reaction as written at 51 degrees C, given that [Zn2+] = 0.837 M and [Sn2+] = 0.0180 M. Zn(s) + Sn^2+(aq) = Zn^2+(aq)+Sn(s) E = __ V Reduction Half-Reaction Standard Potential Ered° (V) Zn2+(aq) + 2e– →

18. ## Chemistry

Assume equal concentrations, rank these solutions by pH HBrO, Ca(OH)2, HCl, KOH, NH3 Here's how I ranked it: highest: Ca(OH)2 > HCl > KOH > NH3 > HBrO lowest is this correct? if not please tell me why!

19. ## Chemistry

A generic solid, X, has a molar mass of 77.7 g/mol. In a constant-pressure calorimeter, 31.2 g of X is dissolved in 289 g of water at 23.00 °C. The temperature of the resulting solution rises to 24.40 °C. Assume the solution has the same specific heat as

20. ## Chemistry

Phosphorus pentachloride decomposes according to the chemical equation PCl5(g) -----> PCl3 (g)+ Cl2(g) Kc= 1.80 at 250 degrees C A 0.206 mol sample of PCl5(g) is injected into an empty 3.30 L reaction vessel held at 250 °C. Calculate the concentrations of

21. ## Math

Shelly compared the number of oak trees to the number of maple trees as part of a study about hardwood trees in a woodlot. She counted 9 maple trees to every 5 oak trees. Later in the year there was a bug problem and many trees died. New trees were planted

22. ## Language Arts

Which of the following sentences contains a dependent clause? a) my mother, who never wastes anything, rinsed and saved the take-out boxes b) we were running late and, we had to skip stopping by the post office. c) I had never been to New York before this

23. ## Math

Tiffany bought 2/5 kg of cherries. Linda bought 1/10 kg of cherries less than Tiffany. How many kg of cherries did they buy altogether?

24. ## Chemistry

I'm a bit iffy on oxidation numbers... can someone please tell me if this is correct? Assign oxidation states to each element on both sides of the equation : KClO2--->KCl+O2 Reactants K = +1 Cl = +1 O = -2 Products K = +1 Cl = -1 O = 0 the element being

25. ## Chemistry

At 25 degrees Celsius all of these are true for a neutral solution : pH = 7.00, pOH = 7.00, and [H+] = [OH-] is that correct? For a neutral, aqueous solution regardless of temperature.. would the only correct statement be [H+] = [OH-]? pH = 7.00 and pOH =

26. ## Physics

Take two Styrofoam cups, partially fill them with equal amounts of cold water, and drop equal amounts of ice into each cup to obtain a mixture of ice and water. a. Stir the water and ice mixture in one of the cups vigorously with a nonmetallic stirrer

27. ## Chemistry

I keep getting the last part of this question wrong. Strong base is dissolved in 765 mL of 0.200 M weak acid (Ka = 4.63 x 10^-5) to make a buffer with a pH of 4.18. Assume that the volume remains constant when the base is added. HA(aq) + OH-(aq) -. H2O(l)

28. ## Chemistry

What mass of precipitate will form if 1.50L of concentrated Pb(ClO3)2 is mixed with 0.200L of 0.280M of NaI? Assume the reaction is complete

29. ## Chemistry

What NaCl concentration results when 209 mL of an 0.660 M NaCl solution is mixed with 492 mL of a 0.270 M NaCl solution? __ mol/.209 L = 0.660 M __ mol/.492 L = 0.270 M .. I have no idea how to solve this. I have no idea why I even set up the equation

30. ## English

Why does Yoni think the Arab he finds is perfect for his film? It was in Bethlehem, actually, that Yonatan found his Arab, a handsome man who used his first wish for peace. His name was Munir; he was fat with a big white mustache. Superphotogenic. It was

31. ## math

an empty rectangle tank with a base area of 2400 cm^2 is filed with water from 2 taps. one tap can fill the tank with 12L of water per minute, while the other tap can do it at 3l less perminute. (A) what will be the depth of water in the tank after both

32. ## Math Statistics

"In the United Kingdom's Lotto game, a player picks six numbers from 1 to 49 fir each ticket. Rosemary brought one ticket for herself and one for each of her four adult children. She had the lottery ticket. When the sic winning numbers were drawn, Rosemary

33. ## Chemistry

Delta H is 20.1 kJ/mol and Delta S is 45.9 J/(mol-k). Assuming these values change very little with temperature, over what temperature range is the reaction spontaneous in the forward direction? Is the reaction spontaneous for temperatures less than or

34. ## AP Stats

Bolivian adult females are much shorter than US females although the standard deviation of their heights is about the same at 2.3 inches. Only 4.1% of Bolivian females are at least five feet tall. What is the mean height of adult Bolivian women assuming

35. ## Chemistry

There is a current being applied to an aqueous solution fo sodium bromide. What is produced at the cathode and anode? I said that Na(s) being produced at the cathode and Br2(l) being produced at the anode. The other options are H2 and O2 for either but

74. ## Language Arts

Which of the following sentences contains a dependent clause? a) my mother, who never wastes anything, rinsed and saved the take-out boxes b) we were running late and, we had to skip stopping by the post office. c) I had never been to New York before this

75. ## social studies

How are petitions and Demonstrations similar?

76. ## science

How many seconds does it take for mercury to go from 0 degrees celsius to 300 degrees celsius?

77. ## Accounting

How do I calculate the future value of the following? $5,000 compounded annually at 12% for 2 years$5,000 compounded semiannually at 12% for 2 years $5,000 compounded quarterly at 12% for 2 years$5,000 compounded monthly at 12% for 2 years

78. ## math

a student playing a computer chess game gets 5 points every time he wins a round.the computer gets 3 points every time it wins a round.they play 64 rounds and end with a tied score.how many rounds did the computer win. please help me .. i think the answer

79. ## Physics

Show that the average speed of a rabbit that runs a distance of 30 m in a time of 2 s is 15 m/s. I have a whole bunch of problems such as these and i'm not sure what math formula to use to figure problem.I know its Acceleration ! change of velocity time

80. ## Chem

The hydrolysis of sucrose into glucose and fructose in acidic water has a rate constant of at 25 degrees C. Assuming the reaction is first order in sucrose, determine the mass of sucrose that is hydrolyzed when 2.60 L of a 0.150 M sucrose solution is

81. ## Physics

A car is backing up at a rate of 10km/hr. If the driver looks through his rear-view mirror, how fast does a tree, which is behind him, appear to approach him?

82. ## Math

Kaylee got a 15% raise. She now earns \$23 an hour. How much did she earn before the raise?

83. ## Chemistry

The voltage generated by the zinc concentration cell described by, Zn(s)|Zn2+ (aq, 0.100 M)||Zn2+ (aq, ____ M)|Zn(s) is 24.0 mV at 25 °C. Calculate the concentration of the Zn2 (aq) ion at the cathode. My textbook advised me to use the Nernst Equation and

84. ## math

container A has twice the capicity of container B. container A is full of sand and container B is empty. suppose 1/8 of the sand in container A is poured into container B. what fractional part of container B will conatin sand.........please halpme i am

85. ## math

What is the base 7 representation of the number 275? 21201 is the base 3 representation of what number? I'm having trouble with both questions. Can someone help me out? I tried using the internet but I was still confused.

86. ## Chemistry

Hydrazine, N2H4 can be made (on paper) by reaction of molecular nitrogen and molecular hydrogen, 2 H 2 ( g ) + N 2 ( g ) --> N 2 H 4 ( g ) and suppose that the equilibrium constant Kp has the value 1×10^–3. (a) A stoicheometric mixture of H2 and N2 is

87. ## Chemistry

how much silver nitrate must be measured to yield 1.00g silver?

88. ## physics 1

Two isolated masses, M1 = 2.20 kg and M2 = 589 kg are initially rest, a distance d= 161 cm apart. Their gravitational attraction is the only force acting. Calculate the time it takes for M1 to move from that distance to 159 cm from M2. Assume that M2 does

89. ## physics

What is the longest wavelength that can be heard by a normal ear?

90. ## math

At Irv's Cycle Rental Shop, Irv renst all knids of cycles: unicyles, tandem bikes, regualr bikes, and even tricycles for little kids. He parks all the cycles in front of the shop with a helmet for each rider strapped to the cycles. This morninf Irv counted

91. ## Chemistry

Given the following equations: 2 H2 (g) + O2 (g)--> 2 H2O (l) deltaH = -571.6 kJ N2 (g) + O2 (g)-->2 NO (g) deltaH = +180.5 kJ N2 (g) + 3 H2 (g) --->2 NH3 (g) deltaH = -92.22 kJ Determine the enthalpy change (deltaH) for the following reaction: 2 NO (g) +

92. ## physics

If each of the three rotor helicopter blades is L = 3.69m long and has a mass of m = 159kg, calculate the moment of inertia of the three rotor blades about the axis of rotation.

93. ## US History

The question is "How might Juan Cabrillo's explorations affect later settlements in CA?" In the book there's only a little sentence talking about him.. "Cabrillo sailed 1,200 miles along the coast of what is now California. Cabrillo failed to find wealth,

94. ## math

37.52 rounded to the nerast whole

95. ## physics

A block is projected up a frictionless inclined plane with initial speed v0 = 8.42 m/s. The angle of incline is è = 58.4°. (a) How far up the plane does it go? (b) How long does it take to get there? (c) What is its speed when it gets back to the bottom?

96. ## math

each face of a cube can be painted either red or yellow. how many differents ways can you paint the cube? i thinks its 18 ways i don't know please help me

97. ## math

you have one penny one nickel one dime and one quarter. how many different amounts of money can you make using one or more of these coins ... please help..me..:(

98. ## math

still don't get it.....Our class planned a holiday party for disadvantaged kids.Some of us baked cookies for the party.On the day of the party,we found we could divide the cookies into packets of two, three, four, five, or six and have just one cookie left

99. ## Math

Express fraction 9/4 as the sum of two or three equal parts. Rewrite the problem as a multiplication equation.

100. ## Chemistry

Suppose we have a solution of lead nitrate, Pb(NO3). A solution of NaCl(aq) is added slowly until no further precipitation occurs. The precipitate is collected by filtration, dried and weighed. A total of 10.27g of PbCl2(s) is obtained from 200.0mL of the

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