# Gabriella

Popular questions and responses by Gabriella
1. ## AP Chemistry

Calculate ∆G0 for the following reaction. 4XY + 3Z2−→2Z3X2+ 2Y2 Substance ∆H0f S0kJ/mol J/mol·K XY 205.0 75.0 Y2 −82.0 37.0 Z2 −25.0 78.0 Z3X2 −245.0 137.0 Answer in units of kJ/mol

2. ## ap chemistry

Under certain conditions, the reaction 3A + 2B -> 4C was observed to proceed at a rate of 0.00348 M· s−1. What was the corresponding rate of change in reactant A?

3. ## AP Chemistry

What is the pH of a 0.41 M solution of pyridinium chloride (C5H5NH+Cl−)? (Kb for pyridine is 1.5×10−9.) Answer in units of pH

4. ## AP Chemistry

Like all equilibrium constants, Kw varies somewhat with temperature. Given that Kw is 7.51×10−13 at some temperature, compute the pH of a neutral aqueous solution at that temperature.

5. ## country report

Waht kind of music do they listen to in Thailand? I'm doing a project about Thailand and as an idea, I thought of either playing traditional music or bringing in Thai food. I'm not sure where to find Thai music (or info about music in Thailand) though.

6. ## AP Chemistry

A 28.4858 g sample of impure magnesium carbonate was heated to complete decomposition according to the equation MgCO3(s)→MgO(s) + CO2(g).After the reaction was complete, the solid residue (consisting of MgO and the original impurities) had a mass of

7. ## AP Chemistry

Which one of the following compounds is not a salt? 1. Ca(ClO4)2 2. Fe(NO3)3 3. Cr(OH)3 4. Na2SO3 5. KMnO4

8. ## AP Chemistry

Consider the ionization constants cyanic acid (HOCN) : Ka= 3.5×10−4; ammonia (NH3): Kb= 1.8×10−5. A solution of ammonium cyanate (NH4OCN) is 1. acidic, because the cation and the anion hydrolyze to the same extent. 2. acidic, because the anion

9. ## math

A circular swimming pool has radius of 15 feet. The family that owns the pool wants to erect a circular fence that is 5 feet away from the pool. Which is the closest to the circumference of the fence they will need? A. 94.2 ft B. 125.6 ft C. 157 ft D.

10. ## AP Chemistry

Iron pyrite (FeS2) is the form in which much of the sulfur exists in coal. In the combustion of coal, oxygen reacts with iron pyrite to produce iron(III) oxide and sulfur dioxide, which is a major source of air pollution and a substantial contributor to

11. ## ap chemistry

Find the equilibrium constant for the reaction Cr(s) + Zn2+(aq)→Cr2+(aq) + Zn(s) if the standard cell emf is −0.76 V at the cathode and −0.91 V at the anode. RT - F= 0.025693 V

12. ## AP Chemistry

Calculate the standard cell emf for galvanic cells with the cell reaction 2H2(g) + O2(g)→2H2O(ℓ)in acidic solution. Answer in units of V

13. ## physical

STATE 4 facts and fallacies abt the effect of sports participation on women reproduction

14. ## physics

a stone is thrown vertically upwards with an initial velocity of 14m/s .neglecting air resistence , find time taken before it reaches the ground .

15. ## English

4.)Which word or phrase is closest in meaning to the word unanimous? a.)justifies b.)in agreement c.)divided d.)not accurate 5.)Which word is the best choice to complete the following sentence?She didn’t want to get in trouble for breaking the window, so

16. ## ap chemistry

What is the pH at the equivalence point in the titration of 10.0 mL of 0.56 M HZ with 0.200 M NaOH? Ka = 6.6 × 10−5 for HZ.

17. ## AP Chemistry

Calculate the standard entropy change for the dimerization of NO2: 2NO2(g)→N2O4(g)at 298 K, if S◦ ∆H◦f J/K·mol NO2(g) 240.06 33.18 N2O4(g) 304.29 9.16 Answer in units of J/K·mol

18. ## Ap chemistry

The standard enthalpy of formation of Mn2O3 is −962.3 kJ/mol. How much heat energy is liberated when 6.4 grams of man- ganese are oxidized by oxygen gas to Mn2O3 at standard state conditions? Answer in units of kJ

19. ## AP Chemistry

An unknown amount of water is mixed with 350 mL of a 6 M solution of NaOH solution. A 75 mL sample of the resulting solution is titrated to neutrality with 52.5 mL of 6 M HCl. Calculate the concentration of the diluted NaOH solution. Answer in units of M

20. ## Pre-Algebra

Use the formula d = rt. Find t for r = 46.6 m/h and d = 456.68 m. Show your work. This question is not multiple choice

21. ## ap chemistry

Calculate the ratio of [NH3]/[NH4+] that gives a solution of pH = 10.60.

22. ## ap chemistry

What mass of solid sodium formate (of MW 68.01)must be added to 125 mL of 0.48 mol/L formic acid (HCOOH) to make a buffer solution having a pH of 4.07? Ka = 0.00018 for HCOOH. Answer in units of g

23. ## AP Chemistry

A 0.00100 M solution of a weak acid HX is 6% ionized. Calculate Ka for the acid.

24. ## ap chemistry

Suppose that coal of density 1.5 g/cm3 is pure carbon. (It is, in fact, much more complicated, but this is a reasonable first approximation.) The combustion of carbon is described by the equation C(s) + O2(g) −! CO2(g) H◦ = −394 kJ What is the value

25. ## AP Chemistry

Given the Na+/Na and K+/K half-cells, determine the overall electrochemical reaction that proceeds spontaneously and the E0 value. Answer in units of V

26. ## AP Chemistry

What volume of water was added to the 350 mL of NaOH solution? Assume volumes are additive. Answer in units of mL

27. ## AP Chemistry

Listerine mouthwash is 21.6% ethyl alcohol by volume. What mass of ethanol is contained in 20.0 mL of mouthwash? (The density of ethanol is 0.789 g/mL.) Answer in units of grams

28. ## AP Chemistry

Sulfuric acid (H2SO4)is prepared commercially from elemental sulfur using the contactprocess. In a typical sequence of reactions,the sulfur is first burned:S + O2→SO2,then it is converted to SO3 using a catalyst:2SO2+O2→2SO3.The resulting SO3 is

29. ## AP Chemistry

An ore contains Fe3O4 and no other iron. The iron in a 36.5-gram sample of the ore is all converted by a series of chemical reactions to Fe2O3. The mass of Fe2O3 is measured to be 26 g. What was the mass of Fe3O4 in the sample of ore? Answer in units of g

30. ## chemistry

If the temperature of a 500.0-g sample of liquid water is raised 2.00c how much heat is absorbed by the water?The specific heat of liquid water is 4.184j/(g*c)

31. ## World History

Which was consequence of the United States entry into world’s war I

32. ## Math

You cut vegetables for a stew. You have 7/8 cup carrots, 1/3 cup onions, and 1/2 cup peppers. About how many cups of vegetable do you have in all? Answers About 1 cup About 2 cups About 3 cups About 1/2 cup

33. ## Math

Estimate the sum or diffrence. Use the bench marks 0, 1/2, 2 2/15 + 13/30 = Answers 0 1/2 1

34. ## ALGEBRA

Factor completely 9x^2 + 42x + 49. A. (3x + 7)(3x − 7) B. (9x − 7)(9x − 7) C. (3x + 7)(3x + 7) D. (9x + 7)(9x + 7) HELP PLEASE DON'T UNDERSTAND

35. ## AP Chemistry

We drop 30 grams of magnesium into 770 mL of a 4 M HCl solution. What is the maximum volume of dry hydrogen that could be produced by this reaction at STP? Mg(s) + 2HCl(aq)→MgCl2(aq) + H2(g) Answer in units of liters

36. ## AP Chemistry

What pressure would a mixture of 3.2 grams of O2, 6.4 grams CH4, and 6.4 grams of SO2 exert if the gases were placed in a 4.1 liter container at 127 degrees C? Answer in units of atm

37. ## AP Chemistry

Nitroglycerin is a shock-sensitive liquid that detonates by the reaction 4C3H5(NO3)3(ℓ)-> 6N2(g)+10H2O(g)+12CO2(g)+O2(g) Calculate the total volume of product gases at 201 kPa and 273 degrees C from the detonation of 3.3 lb (1496.9 g) of nitroglycerin.

38. ## AP Chemistry

A solution of AgI contains 1.2 mol/L Ag+. Ksp of AgI is 8.3×10^17. What is the maximum I− concentration that can exist in this solution? Answer in units of mol/L

39. ## AP Chemistry

A mixture consisting of 1 mol of H2O(g) and 1 mol CO(g) is placed in a 11 L reaction vessel at 800 K. At equilibrium, 0.422 mol CO2(g) is present as a result of the reaction CO(g) + H2O(g)CO2(g) + H2(g). What is Kc at 800 K?

40. ## AP Chemistry

The equilibrium constant for thermal dissociation of F2 F2(g)2F(g) is 0.300. If initially 1.00 mol F2 is placed in a 1.00 L container, which of the following is the correct number of moles of F2 that have dissociated at equilibrium? 1. 0.130 mol 2. 0.418

41. ## AP Chemistry

Analysis of a reaction mixture showed that it had the composition 0.43 mol/L N2, 0.541 mol/L H2, and 0.124 mol/L NH3 at 800 K, at which temperature Kc=0.278 for N2(g) + 3H2(g)2NH3(g). Calculate the reaction quotient Qc

42. ## AP Chemistry

The equilibrium constant Kp is 5.00×10^17 at 25◦C for the reaction C2H4(g) + H2(g)C2H6(g). From this information, calculate ∆G0 at 25◦C

43. ## ap chemistry

What is the activation energy Ea for this reaction? Answer in units of kJ The deltaH is 160 kJ X is at 160 (beginning of reaction) Y is at 300 (end of reaction)

44. ## AP Chemistry

The standard enthalpy of formation of Mn2O3 is −962.3 kJ/mol. How much heat energy is liberated when 6.5 grams of manganese are oxidized by oxygen gas to Mn2O3 at standard state conditions? Answer in units of kJ

45. ## ap chemistry

Consider the specific heats H2O(s) =2.09 J/g ¡¤◦C,H2O (§¤) = 4.18 J/g ¡¤◦C, and H2O(g) = 2.03 J/g ¡¤◦C. The heat of fusion for water is 334 J/g and its heat of vaporization is 2260 J/g. Calculate the amount of heat required to convert 92 g of

46. ## ap chemistry

A sample of 1.67 grams of Z is dissolved into 500 grams of water which is in a Styrofoam coffee cup. The temperature is monitored and is found to rise from 25.594◦C to 26.041◦C. What is Hsolution for substance Z? Assume no heat is lost/gained by the

47. ## AP Chemistry

A typical bathtub can hold 93 gallons of water. Calculate the mass of natural gas that would need to be burned to heat the water for a tub of this size from 60◦F to 99◦F. Assume that the natural gas is pure methane(CH4) and that the products of

48. ## AP Chemistry

a student titrates three samples of 0.3% hydrogen peroxide solution made from a bottle of 3% hydrogen peroxide solution dated 10/31/2007. would you expect the calculated molarities of the samples to be higher or lower than the following values: trial 1:

49. ## ap chemistry

A total charge of 96.5 kC is passed through an electrolytic cell. What mass of silver metal will be produced from a silver nitrate solution? Answer in units of g

50. ## AP Chemistry

For the reduction of Cu2+by Zn, ∆G◦=−212 kJ/mol and E◦= +1.10 V. If the coefficients in the chemical equation for this reaction are multiplied by 2, ∆G◦=−424 kJ/mol. This means E◦= +2.20 V. True or false?

51. ## AP Chemistry

redox reaction: Hydrogen peroxide is added to an acidified solution of potassium permanganate. what is the total redox reaction?

52. ## AP Chemistry

How many milliliters of a 0.62 M HCl solution are needed to react completely with 4.7 g of zinc to form zinc(II) chloride? Answer in units of mL

53. ## Physics

Contrast the metric units of distance, time, and speed. Describe the relationship between them.

54. ## Special Angles

>Find m∠BAC and m∠DAB in the figure shown below.Line upper D upper C is shown intersecting with line upper E upper B at point upper A. The angle upper E upper A upper D is labeled 80 degrees." width="169" height="70" align="middle" style="border: 0px

55. ## science

What do the bone marrow and the epidermis have in commen

56. ## Math

A shopper keeper sold a total of 15 boxes of pencils on Monday and Tuesday. She still three more boxes on Monday then on Tuesday. There were 12 pencils in each box. How many pencils did she sell on Monday?

57. ## college algebra

A piece of machinery valued at \$30,000 depreciates at a rate of 10% yearly. How long will it take for it to reach a value of \$15,000?

58. ## College Algebra

The centripetal force of an object moving around a circle varies directly with the square of the speed and inversely as the radius of the object. Suppose the force is 300 N when the speed is 15 m/s and the radius is 5m. What would the force be if the speed

if a car is moving at some speed and then goes twice as far, would the braking distance be twice as far? yes or no? explain

60. ## math

A mile is 5280 feet. Between which two integers is the elevation in miles?

61. ## Statistics

The average daily high temperatures in Lawton are approximately normally distributed with a mean of 58 degrees and a standard deviation of 12 degrees. Find the probabilities below: The probability that the high would not exceed 65 degrees on any one day.

62. ## physics

A car moves from rest with a constant acceleration of 4m/s squared for 5s .IT then continues with the speed attained for10s and then accelerates at 2m/s squared for 10s.A/ SKETCH A SPEED TIME GRAPH FOR THE WHOLE MOTION GIVING YOUR VALUES ON BOTH

63. ## Pre-Algebra

1.)Identify the underlined place in the decimal number 83.5 8 41.Round the number to that place. a.)thousandths;83.58 b.)hundredths;83.59 c.)hundredths;83.58 d.)thousandths;83.59 2.)Estimate \$5.56 + \$13.02 using front-end estimation. a.)about \$19.60

64. ## Algebra

The cruising speed of an airplane is 150 mph. You plan to hire the plan for a 3 hour sightseeing trip. You instruct the pilot to fly as far north as she can and still return to the airport at the end of the allotted time. How far north should the pilot fly

65. ## AP Chemistry

Use the Clausius-Clapeyron equation to calculate the temperature at which pure water would boil at a pressure of 367 torr. The heat of vaporization of water is 43105 J/mol at 100◦C. Answer in units of ◦C

66. ## AP Chemistry

Benzene is a hydrocarbon that is commonly used as a commercial solvent. However, it is carcinogenic; i.e., accumulations in the body can cause cancer. What is the vapor pressure of benzene at 58◦C? The normal boiling point of benzene is 80.0◦C and its

67. ## AP Chemistry

The rate of effusion of unknown gas X is found to be about 1.5 times that of SF6 gas (MW=146 g/mol) at the same conditions of temperature and pressure. What is the molecular weight of gas X? Answer in units of g/mol

68. ## AP Chemistry

A 1277 mL sample of nitrogen (N2) was collected by displacement of water at 24 degrees C under a total barometric pressure of 966 torr. What mass of dry nitrogen was collected? The vapor pressure of water at 24 degrees C is 22 torr. Answer in units of g

69. ## AP Chemistry

Part 1 of 3: An apparatus consists of a 2 L flask containing nitrogen gas at 30 degrees C and 758 kPa, joined by a valve to a 11 L flask containing argon gas at 30 degrees C and 49.7 kPa. The valve is opened and the gases mix. What is the partial pressure

70. ## AP Chemistry

We observe that 5 grams of a gaseous com- pound occupies 2083 mL at 50 degrees C and 574 torr. What is the molecular weight of the compound? Answer in units of g/mol

71. ## AP Chemistry

A 2.8 gram sample of a gaseous substance occupies 12 L at 47 degrees C and 683 torr. What is the density of the gas under these conditions? Answer in units of g/L

72. ## AP Chemistry

To what temperature must a sample of helium gas be cooled from 110 degrees C to reduce its volume from 4.9 L to 0.7 L at constant pressure? Answer in units of K

73. ## AP Chemistry

what is the pKa of an acid that has a pH of 7.4 at neutralization and has to have 25 mL added to neutralize it

74. ## ap chemistry

What is the ratio of the molarities of PO3^4- and HPO4^2− ions in a buffer solution having a pH of 13.16? What mass of K3PO4 must be added to 1 L of 0.1 M K2HPO4(aq) to prepare a buffer solution with a pH of 13.16? Answer in units of g What mass of

75. ## ap chemistry

What is the pH at the point during a titration when 34 mL of 0.200 M HCl has been added to 29 mL of 0.0500 M NH3 solution? HCl is a strong acid, Kb=1.8×10−5 for NH3. Answer in units of pH

76. ## ap chemistry

Calculate the pH at the equivalence point for the titration of a solution containing 150.0 mg of ethylamine (C2H5NH2) with 0.1000 M HCl solution. The volume of the solution at the equivalence point is 250.0 mL. Kb for ethylamine is 4.7 × 10−4.

77. ## ap chemistry

How many moles of sodium acetate (NaCH3COO) must be added to 1.000 liter of a 0.500M solution of acetic acid (CH3COOH) to produce a pH of 5.027? The ionization constant of acetic acid is 1.8 × 10−5. Answer in units of mol

78. ## ap chemistry

The ionization constant of HF is 7.2 × 10−4. What is the molar concentration of H+ in a solution which is 0.353 molar in HF and 0.145 molar in KF?

79. ## ap chemistry

What is the concentration of hydrogen ions in a solution containing 0.785 M HOCN (cyanic acid) and 0.659 M (NaOCN) (sodium cyanate)? The ionization constant of cyanic acid is 3.5 × 10−4. Answer in units of M

80. ## ap chemistry

What is the concentration of H+ ions in a buffer solution containing 0.305 M benzoic acid (with ionization constant 6.5 × 10−5)and 0.834 M sodium benzoate (a salt of benzoic acid)?

81. ## ap chemistr

The ionization constant of HA is 1×10−6. What must be the ratio of [A−] to [HA] for the preparation of a buffer solution with a pH of 5.74?

82. ## ap chemistry

A buffer solution is made by dissolving 0.45 moles of a weak acid (HA) and 0.23 moles of KOH into 680 mL of solution. What is the pH of this buffer? Ka = 2.4×10−6 for HA.

83. ## AP Chemistry

If 435 mL of 2.7 molar HCl solution is added to 128 mL of 3.2 molar Ba(OH)2 solution, what will be the molarity of BaCl2 in the resulting solution? Answer in units of M

84. ## AP Chemistry

If 400 mL of 3.2 molar HCl solution is added to 300 mL of 2 molar NaOH solution, what will be the molarity of NaCl in the resulting solution? Answer in units of M

85. ## AP Chemistry

A 65 mL sample of a solution of sulfuric acid is neutralized by 46 mL of a 0.14 M sodium hydroxide solution. Calculate the molarity of the sulfuric acid solution. Answer in units of mol/L

86. ## AP Chemistry

How many moles of NaOH will it take to neutralize 0.77 L of 0.81 M HCl? Answer in units of mol

87. ## AP Chemistry

50.0 mL of an HCl solution with a pH of 3.5 neutralizes 200.0 mL of a Ca(OH)2 solution. What is the molarity of the Ca(OH)2 solution?

88. ## algebra 2

Cube root (x+8)-6=-2

3(x-2)^4=24

90. ## AP Chemistry

A given weak acid HZ has a Ka=1.7×10−6. What is the H3O+ concentration of a solution of HZ that has a concentration of 0.78 mol/L? What is the pH of this solution of HZ? What is the percent ionization of HZ in this solution? Answer in units of %

91. ## AP Chemistry

The pH of a solution of hydrochloric acid is 1.67. What is the molarity of the acid? Answer in units of mol/L

92. ## AP Chemistry

The ionic substance T3U2 ionizes to form T2+ and U3− ions. The solubility of T3U2 is 4.07×10−20 mol/L. What is the value of the solubility-product constant?

93. ## AP Chemistry

What is the value of Ksp for Ag2SO4 if 5.70 g is soluble in 1.00 L of water?

94. ## AP Chemistry

Calculate the solubility product constant for calcium carbonate, given that it has a solubility of 5.3×10^7 g/L of water.

95. ## AP Chemistry

Calculate the concentration of Hg2+ ions in a saturated solution of HgS(s). (Ksp=1.7×10^52) Answer in units of mol/L What volume of solution contains one Hg2+ ion? Answer in units of L/ion

96. ## AP Chemistry

The system CO2(g) + H2(g)H2O(g) + CO(g) is at equilibrium at some temperature. At equilibrium a 4.00 L vessel contains 1.00 mole CO2, 1.00 mole H2, 2.40 moles H2O, and 2.40 moles CO. How many moles of CO2 must be added to the system to bring the

97. ## AP Chemistry

The equilibrium constant for the reaction PCl3(g) + Cl2(g) PCl5(g) is 35000 at 760◦C. At equilibrium, the partial pressure of PCl5 was 110 bar and that of PCl3 was 9.98 bar. Calculate the equilibrium partial pressure of Cl2. Answer in units of bar

98. ## AP Chemistry

At 350 K, Kc= 0.142 for the reaction 2BrCl(g) Br2(g) + Cl2(g) An equilibrium mixture at this temperature contains equal concentrations of bromine and chlorine, 0.049 mol/L. What is the equilibrium concentration of BrCl? Answer in units of M

99. ## AP Chemistry

At a certain temperature, the equilibrium constant Kc is 0.154 for the reaction 2SO2(g) + O2(g) 2SO3(g) What concentration of SO3 would be in equilibrium with 0.250 moles of SO2 and 0.885 moles of O2 in a 1.00 liter container at this temperature? Note: