jin

Popular questions and responses by jin
1. chemistry

Predict whether the following solutions are acidic, basic, or nearly neutral: a. NaBr, b. K2SO3, c. NH4NO2, d. Cr(NO3). the answer is neutral, basic, acidic, acidic and i am not sure why

2. chemistry

How do you know if these solutions are acidic, basic, or nearly neutral? a. NH4NO2 b. Cr(NO3)3

3. physics

In Figure (a), a block of mass m lies on a horizontal frictionless surface and is attached to one end of a horizontal spring (spring constant k) whose other end is fixed. The block is initially at rest at the position where the spring is unstretched (x =

4. chemistry

lithium + gold(III) chloride +lithium chloride + gold need to balance equation

5. chemistry

how do you solve this problem?? What is the original molarity of a solution of formic acid (HCOOH) whose pH is 3.26 at equilibrium? the answer is 2.3 x 10^-3M.

6. PHYSICS

Wile E. Coyote is holding a “HEAVY DUTY ACME ANVIL” on a cliff that is 40.0 meters high. The Roadrunner (beep-beep), who is 1.0 meter tall, is running on a road toward the cliff at a constant velocity of 10.0 m/s. Wile E. Coyote wants to drop the anvil

7. math

If a ball is thrown straight up into the air with an initial velocity of 95 ft/s, it height in feet after t second is given by y=95t–16t2. Find the average velocity for the time period begining when t=1 and lasting (i) 01 seconds: (ii) 001 seconds: (iii)

8. Physics

An orange rolls across a table with a speed of 0.5 m/s and falls off the edge. If it lands 3 m from the edge of the table, from what height does it fall?

9. algebra

A ball is thrown into the air with an upward velocity of 28 ft/s. Its height (h) in feet after t seconds is given by the function h = –16t² + 28t + 7. How long does it take the ball to reach its maximum height? What is the ball’s maximum height? How

10. chemistry

How do you solve this problem? In a certain industrial process involving a heterogeneous catalyst, the volume of the catalyst (in the shape of a shpere) is 10.0cm^3. Calculate the surface area of the catalyst. IF the sphere is broken down into eight

11. chemistry

for SCN- if S-C has a bond order of 1, S=C and C=N have bond orders of 2, and C triple bond N hasa bond order of 3, ... Do the bond length in SCN- point to one resonance structure over the other? Which one?

12. math

Draw a picture that represents 3x50=150?

13. chemistry

Write balanced equations and solubility product expressions for the solubility equlibria of the following compounds: a. CuBr b. ZnC2O4 c. Ag2CrO4 d. Hg2Cl2 e. AuCl3 f. Mn3(po4)2 can you give me some examples using the compounds given?

14. calculus

A street light is at the top of a 16 ft tall pole. A woman 6 ft tall walks away from the pole with a speed of 4 ft/sec along a straight path. How fast is the tip of her shadow moving when she is 40 ft from the base of the pole?

15. math

An open box is to be made from a flat piece of material 18 inches long and 2 inches wide by cutting equal squares of length xfrom the corners and folding up the sides. Write the volume Vof the box as a function of x. Leave it as a product of factors, do

16. 9 th science

distinguish between tolerance range and optimal range

17. chemistry

Explain, with balanced ionic equations, why a. CuI2 dissolves in ammonia solution b. AgBr dissolves in NaCN solution, c. HgCl2 dissolves in KCL solution.

18. math

A spherical snowball is melting in such a way that its diameter is decreasing at rate of 0.2 cm/min. At what rate is the volume of the snowball decreasing when the diameter is 12 cm. (Note the answer is a positive number).

19. chemistry

LAST QUESTION: When solid NH4NO3 decomposes, a mixture of gases is obtained: 2 NH4NO3(s)--> 4H2O(g) + O2(g) + 2 N2(g) In an experiment, 5.02 g NH4NO3 decomposes completely in a rigid 5.00-L container. What is the total pressure in the container if the

20. chemistry

Determine the oxidation state of each transition metal in the following cmpds. (a) Na2MoO4 (b) KAuCl4 (c) MgWO4 and (d) Ni(CO)4

21. chemistry

The pH of a 0.0642 M solution of a monoprotic acid is 3.86. s this a strong acid? the answer is no, can you explain why??

22. chemistry

Discuss the spontaneity of an electrochemical reaction in terms of its standard emf (E¨¬cell)

23. chemistry

Solid NaI is slowly added to a soln that is 0.010M in Cu+ and 0.010M in Ag+. a. Which compound will begin to precipitate first? b. Calculate [Ag+] when CuI just begins to precipitate/ c. What percent of Ag+ remains in solution at this point?

24. Algebra

For 1980 through 1990, the average weekly earnings (in dollars)for workers in the United States can be modeled by E= 14.5t + 270, where t is the number of years since 1980. Approximate the average weekly earnings in 1980 and 1990. I am having trouble

25. chemistry

I had this on a test, not sure how to do it Explain, using balanced chemical reactions with the smallest integer coefficients, why each of following occurs. a. CuI2 (insoluble in pure water) dissolves readily in aqueous ammonia, HN3(aq) b. AgBr (insoluble

26. chemistry

Which of the following when added to 100.0mL of a 0.100M soln of NH4Cl would produce a buffer soln? a.100.0mL of 0.100 M HCl soln b. 100.0mL of 0.050M NaOH soln c. 100.0mL of 0.100M NaOH soln d. 100.0mL of 0.050M NH4No3 soln e.none of the above

27. math

how do you find sin7x/4x when lim x goes to 0 the answer is 7/4

28. calculus

The circumference of a sphere was measured to be 78.000 cm with a possible error of 0.50000 cm. Use linear approximation to estimate the maximum error in the calculated surface area. Estimate the relative error in the calculated surface area.

29. math

If a ball is thrown vertically upward from the roof of 32 foot building with a velocity of 80 ft/sec, its height after t seconds is s(t)=32+80t–16t2. What is the maximum height the ball reaches? What is the velocity of the ball when it hits the ground

30. physics

A girl with a 69.2 g yo-yo is swinging it in a horizontal circle at an angular velocity of 6.55 rad/s. If the string is tilted down at an angle of 20.4°, what must the length of the yo-yo string be?

31. chemistry

how do you solve this problem? consider the reaction A->B the rate of the reaction is 1.6 x 10^-2 M/s when the concentration of A is 0.35 M. Calculate the rate constant if the reaction is a) first order in A and b) second order in A.

32. chemistry

It takes 19.6 mins for a 10.0mL sample of an unknown gas to effuse through a pinhole. A 10.0mL sample of He, required 5.05mins. What is the molar mass of the unknown gas? I got that you have to do : effuse rate of He/Effuse rate of Mx = Square root of

33. chemistry

The Fe(ox)33– complex ion creates an emerald green solution when dissolved. The observed solution color of the complex indicates the size of o is: A. large. B. small. C. in between. D. inconclusive, more information is needed. The observed solution color

34. Economics

Suppose that 20 workers were required in 2010 to produce 120,000 bushels of wheat on a 1,000-acre farm. a. What is the average output per acre? (?) bushels per acre What is the average output per worker? (?) bushels per worker b. If in 2020 only 16 workers

35. calculus

se differential, i.e., linear approximation, to approximate (8.4)^(1/3) as follows: Let f(x)=(x )^(1/3). The linear approximation to f(x) at x=8 can be written in the form y=mx+b where m is: and where b is: Using this, we find our approximation for

36. science

Would you expect the dissolved oxygen concentration of water samples taken from a lake at 7 am to be higher or lower than samples takn at 5 pm? I feel like there may be more dissolved oxygen in the sample taken at 7 am because photosynthesis probably took

37. Geography

Sailing west from England on which continent would you first make landfall?

38. chemistry

The decomposition reaction, x-->products, is second-order with rate constant k=0.0183 L/(s)(mol). How long will it take for the decomposition to be 95% complete, if the intitial concentration of X is 1.25mol/L? Thanks

39. chemistry

why is it that [H2O] is NOT included in the rate law, even though it is a reactant?

40. math

he circumference of a sphere was measured to be 78000 cm with a possible error of 050000 cm. Use linear approximation to estimate the maximum error in the calculated surface area.

41. Math

Tickets to the school play cost \$4 for adults and \$2 for students. If 255 adults and 382 students attended the play, write an expression that shows the total amount of money made on ticket sales. Then evaluate the expression.

42. math

The horizontal asymptotes of the curve y=12x/(x4+1)^(1/4)

43. math

In the theory of relativity, the mass of a particle with velocity v is m=mo/(square root ((1- v^ 2)/ c^2)) where mo is the mass of the particle at rest and ci s the speed of light. What happens as v goes to c?

44. chemistry

The values of Ksp for AgBr and AgCl, are 7.7x10^-13 and 1.6 x 10^-10. A solution containing a mixture of 2.0x10^-2 M Br and 2.0 x 10^-2M Cl is a candidate for separating using selective precipitation. Solid AgNO3 is added, with a miniature spatula, and

45. chemistry

In titration of a 0.10M soln of Na2Co3 with HCL which of the following will be present in the largest concentration at the first equivalence point? a. Co3^2- b. HCO3- c. H+ d. H2CO3 e. OH-

46. Calculus

find all values of x for which function is differentiable. y=lnx^2 why is the answer= for all x doesn't equal 0?

47. chemistry

Determine the overall orders of the reactions to which the following rate laws apply: a) rate= k[NO2]^2 b) rate = k c) k [H2][Br2]^1/2 d) k [NO]^2[O2] is it.. a. 2 b. 0 c. 1 1/2 d. 3

48. physics

A skier leaves the end of a ramp with a velocity of 25.3 m/s and lands 50.3 m from the base of the ramp. How high is the end of the ramp from the ground?

49. Calculus

find the derivative y= csc^-1 (secx) 0 less than or equal to x less than or equal to 2¤Ð what did i do wrong? - 1/ secx sqrt(secx^2 -1) * secxtanx

50. calculus

Consider the function f(x)=–3x3–1x2+1x+1Find the average slope of this function on the interval (–2–1). By the Mean Value Theorem, we know there exists a c in the open interval (–2–1) such that f(c) is equal to this mean slope. Find the value

51. chemistry

how do you solve this problem?? how much NaOH (in grams) is needed to prepare 546mL of solution. What is the pOH of the solution?

52. Math

Two tourists went on a hike at dawn. One went from a to b and another one went from b to a. They met at noon but did not stop and continued walking maintaining same speed for the whole trip. One finished his hike at 4pm in B and another one came to A at 9

53. chemistry

Which of the following salts would show an appreciable pH-dependent solubility? a. AgCl b. Mg(OH)2 c. BaF d. both b and c e. all of the above I put c as my answer (not sure if its right, but can you explain how you would solve this)

54. chemistry

Faraday¡¯s Law of Electrolysis • Practice Problem. • What is the oxidation state of the osmium atom in an unknown salt if 26.7 grams of osmium plate out when a current of 15 amps is passed through a solution of this salt for 1 hour?

55. chem

For a primitive cubic unit cell, r=6.0 what is the body diagonal in terms of r, the lattice pt radius

56. chemistry

Carbon monoxide, CO and hydrogen, H2, react accordingly: 4CO(g)+9H2(g)-->C4H10(g)+4H2O What volume of the EXCESS REACTANT remains if 17.2L CO and 42.1L H2 are allowed to react? Assume both gases are measured at 711 degree celsius and 1.33atm.

57. chemistry

Rates of chemical reactions usually depend on temperature and pressure. However, half-life of all radioactive elements is independent of both T and p. How can these decay rates be independent of T if we beleive in the Arrhenius equation?

58. Biology

I had to observe slides of onion root tip to study plant mitosis. And the question I have to answer asks,if your observations had not been restricted to the area of the root tip that is actively dividing, how would your results have been different? I

59. calculus

f(x)=8x^3+1x^2–8x+2/–7x^2–4x+9 Find the equation of the non-vertical asymptote. y = Does f(x) intersect its non-vertical asymptote? (yes or no) What is the smallest value of x at which f(x) intersects its non-vertical asymptote? ( Enter No in the

60. unscrable this phrase

Need help in unscrambling this phrase: MTLEFKOTRYETEEMCISRTRAE for what subject?Is this for What subject is this for? capilpsean (toy) ttstelli can you unsramble this (ttstelli) resdoita Littlest

61. Math

How many toothpicks are needed for nth design? Explain how do you figure out.

62. math

if f(x)is greater or equal to 10x–42 but less than or equal to x2+2x–26 determine limx4f(x) = What theorem did you use to arrive at your answer?

63. calculus

find the domain of function f(x)= (5x + 4)/(x^2 + 3x + 2) is the answer.. x can't be -2 or -1?

64. chemistry

The amount of indicator used in an acid-base titration must be small. why??

65. chem

The total pressure in a flask containing air and ethanol at 257C is 878 mm Hg. The pressure of the air in the flask at 257C is 762 mm Hg. If the flask is immersed in a water bath at 400C, the total pressure is 980 mm Hg. The vapor pressure of ethanol at

66. Environmental science

I know how environmental science branches off to various sciences- how does astronomy (to be specific, the discovery that Pluto's not a planet anymore) relates to environmental science? Thank you! Reclassifying Pluto as "not a planet" is NOT a discovery.

67. chemistry

What is the density of CH4 gas at 32.7 degree celsius and 109kPa? The molar mass of CH4 is 16.042g/mol.

68. math

how does secx(tanx + tan^2x- sec^2x) simplified to sec x (tanx -1)?

69. chemistry

how do you solve this? The candy indistry converts sucrose (C11H22O11,table sugar),a crystalline material, to invert sugar, a hydrolzyed [rpdict tjat os 50:50 frutose and glucose. The hydrolysis occurs in water, quite slowly, at an elevated temperature of

70. chemistry

A salt that could decrease the ionization of HCOl in soln is probably a. NaOH b. NaCl c. NaOCl d. NaH e. none of these how would you solve this

71. chemistry

To have a color, the transition metal complex should have an electron in a d-orbital, and an unoccupied spot in a higher energy d-orbital. • Practice Problem. • Predict whether each of the following complexes could be colored: (a) [Sc(H2O)6]3+ (b)

72. chemistry

The pKa for hydrochloric acid is −6.0. What is the concentration of HCl(aq) we would expect to find in a 1 M solution of hydrochloric acid? What pH would we expect? how do you solve this problem?

73. chemistry

why is it that [H2O] is NOT included in the rate law, even though it is a reactant?

74. chem

7.50gram quantity of a diprotic acid was dissolved in water and made up to exactly 250ml. If 25ml of this solution were neutralized by 11.1 mL of 1.0 M KOH then what is the molar mass of the acid? I did 7.50/5.55x10^-3

75. chemistry

how do you know which bonds have a more pie bonding character than the other bond? and how do you know if it point to one resonance structure over the others?

76. Accounting

How does the frequency of interest compounding, regardless of the rate of interest or period of accumulation, affect the future value of any given amount?

77. chem

When a student plotted ln [vapor pressure of a gas] vs. inverse Kelvin temperature, she obtained a straight line with a slope equal to -8.000 x 10^3 K. According to the Clausius Clapeyron equation, Hvap is ? kJ/mol.

78. Math

How many toothpicks are needed for nth design? Explain how do you figure out.

79. chemistry

I'm working on substitution organic chemistry problems and I just had a question. There's an equation in which a molecule is treated with methanol in an acetone solution. Would the reaction be SN1 or SN2? I thought that it was SN2 because of the aprotic

80. chemistry

A reaction has a first order rate constant of (6.25x10^-5 1/s) at T=298.15K and (0.0000538 1/s) at T=338.15K. What is the value of the rate constant at T=316.15K?

81. math

If f(x)=(x^2+3x+4)^2 how do you find the derivative I tried doing 2 (2x+3)..

82. chemistry

the chapter is about chemical kinetics Reaction mechanisms: What does it mean by mechanism of a reaction? What is an elementary step? what is the molecularity of a reaction?

83. chemistry

how do you solve this What is the pH of the solution created by combining 2.60 mL of the 0.10 M NaOH(aq) with 8.00 mL of the 0.10 M HCl(aq)? with 8.00 mL of the 0.10 M HC2H3O2(aq)? mL NaOH 2.60 pH wHCl: _ pH wHC2H3O2 : _ Complete the table below: What are

84. chemistry

Which reactants in the reactions below are acting as Br©ªnsted-Lowry bases? NH4 +(aq) + OH−(aq) NH3(aq) + H2O(l) H2PO4 −(aq) + H2O(l) H3O+(aq) + HPO4 2−(aq) is the answer H2O and the H3O+

85. chemistry

how do you know which resonance structure is more stable according to the energy? does higher energy mean more stable?

86. Bio

why does pH of the matrix increase when electrons flow along the electron transport chains of mitochondria?

87. Sentences

I'm having trouble understanding what kind of sentences these are: Compound? Compound-complex? Declarative? Interrogative? Imperative? Loose? Periodic? Thank you! Tyr here: http://www.eslincanada.com/englishlesson2.html Then here:

88. chemistry

The activation energy, Ea, for a zeroth-order reaction, X-->products, is most readily obtained from the slope of a plot of: (choose from below) -[X] vs time -ln k vs time -rate vs time -[X]^2 vs time -ln[X] vs time -1/[X] vs time -ln k vs 1/T, where T is

89. chemistry

if a college student went into the lab and produced 45 grams of Na2CO3, what is percent yield of this trial?

90. History

Describe and evaluate President Eisenhower’s policy regarding Joseph McCarthy.

91. math

How do you find the derivative of square root of five /t^5? how do you find the derivative of square root of five /t^5 I know that f=a t^-n f'= -an t^(-n-1) and i tried putting -25/{[2sqrt(5/t^5)]/(t^4)}

92. chemistry

how do you solve this? What is the pH of the solution created by combining 12.30 mL of the 0.10 M NaOH(aq) with 8.00 mL of the 0.10 M HCl(aq)? with 8.00 mL of the 0.10 M HC2H3O2(aq)? mL NaOH pH wHCl pH wHC2H3O2 12.30 Complete the table below: What are the

93. Science.

What effect does water loss (through heavy perpiration) have on a person's endocrine system?

94. Calculus

If you have a geometric alternating series, and you prove that the series is converging by doing geometric series test, and NOT alternating series test, then does that allow you to say that the series converges ABSOLUTELY? Or should you do alternate series

95. Calculus MATH

Problem statement a) Suppose f(x) is defined on 0 ≤ x ≤ 1 by the following rule: f(x) is the first digit in the decimal expansion for x. For example, f(1/2) = 5 and f(0.719) = 7. Sketch the graph of y = f(x) on the unit interval with appropriate scales

96. chemistry

According to the mechanism below, what is the correct expression for the rate consumption of A? In the mechanism, M is a molecule that collides with A and A* is a highly-energized for of A. Step 1: A+M A*+M : rate constants k1 and k-1 Step 2: A* C : rate

97. math

how do you find the equation of a line knowing (-5,-5) and (-2.-3) so the slope will be 2/3...

98. math

evaluate the limit as lim h goes to 0 ((2+h)^3 - 8)/h the answer is twelve but I don't know how to factor out the cube

99. math

if f(x)is greater or equal to 10x–42 but less than or equal to x2+2x–26 determine limx4f(x) = What theorem did you use to arrive at your answer?