# Posts by summer

Total # Posts: 434

1. ### Math

Suppose a tree on your land has a radius of 3 inches and increases in radius one-fourth inch a year. How many years, y, to the nearest tenth will it take for the volume of the tree to double? In other words, for what value of y would the following be true? [(1/3)?k(3 + ¼...
2. ### Precalc

According to an article by Thomas H. McMahon in the July 1975 issue of Scientific American, a tree’s height varies directly with the radius of the base of its trunk. He expressed this relation using the formula h = kr^2/3 where k is a constant, h is the tree’s height...
3. ### Chemistry

If the pH of a Ca(OH)2 solution is measured as 9.0, what is the concentration of the Ca(OH)2 solution? 1 × 10-5 M 1 × 10-9 M 1 × 10-8 M 1 × 10-6 M
4. ### Chemistry (pressure)

8 grams of C3H4 gas occupies a volume of 8.2 L at 300 K temperature. Assume ideal gas behavior. The ideal gas constant is 0.082 (L·atm)/(K·mol), and the molecular mass of C3H4 is 40 g/mol. How much pressure is the gas applying to the walls of its container?

6?
6. ### Chemistry

?? ==> 15/7 N + 0/-1 e What is the reactant for this equation? 15/6 C 16/5 B 14/6 C 14/5 B
7. ### Chemistry (specific heat)

1125 J of energy is used to heat 250 g of iron. After heating, the final temperature of the iron is measured as 55 °C. The specific heat capacity of iron is 0.45 J/(g·°C). What was the initial temperature of the iron?
8. ### Chemistry

C(g) + 2A(g) ? 3E(s) + 2F(g) The concentrations of C, A, and F are measured as 0.2 M, 0.2 M, and 0.4 M at equilibrium and at 100 K. What is the value of the equilibrium constant?

100?
10. ### Chemistry

If 10.0 g of substance X dissolved in 100 mL of solution, and the molarity of the solution is 1.0 M, what is the molar mass of substance X? 1000 g/mol 10 g/mol 1 g/mol 100 g/mol
11. ### Chemistry

I’m confused. I multiplied 0.130 by 0.02 and got 0.0026. However, the only options I have are: 0.024 0.066 0.026 0.260

0.026?
13. ### Chemistry

During a titration experiment, a 130.0 mL solution of 0.02 M hydrogen chloride (HCl) is neutralized by 100.0 mL of unknown concentration of lithium hydroxide (LiOH). In this experiment, how many moles of lithium hydroxide are used? 0.024, correct?
14. ### Chemistry (concentration)

That makes sense. So the answer would be 44 g/L?
15. ### Chemistry (concentration)

H2SO4(aq) + 2LiOH(aq) ? Li2SO4(aq) + 2H2O(l) 3.2 moles of LiOH enter the reaction and are fully consumed. The molar mass of Li2SO4 is 110 g/mol. The final aqueous solution has a volume of 4.0 L. What is the final concentration of Li2SO4 in g/L? 44 g/L ...
16. ### Chemistry

X(g)+ 2Y(s) + 3Z(g) ? 2L(g) + 4T(g) If this reaction occurs in one step, what is the order of this reaction? I am not even sure what this means. Could someone explain?
17. ### Chemistry (latent heat)

If 44.25 kJ of heat are released by changing 150. g of liquid mercury to mercury vapor, what is the latent heat of vaporization for mercury in kJ/kg? 29,500 kJ/kg 0.3 kJ/kg 295 kJ/kg 3.4 kJ/kg I believe the answer is 295 but I am not sure
18. ### Chemistry

What could it be then?
19. ### Chemistry

A straight-chain alkene with seven carbons has two double bonds and one bromine atom bonded to one of the carbons. Which option correctly describes the general formula for this alkene?  C7H9Br C7H13Br C7H7Br C7H11Br The answer I have is, C7H13Br. Is this correct?
20. ### Chemistry

If the standard cell potential of zinc-copper cell is 1.10 V and the reduction potential of Cu is 0.34 V, what is the reduction potential of Zn? The answer is -0.76, correct?
21. ### Latent heat of vaporization

If 44.25 kJ of heat are released by changing 150. g of liquid mercury to mercury vapor,  what is the latent heat of vaporization for mercury in kJ/kg? 29,500 kJ/kg 0.3 kJ/kg 295 kJ/kg 3.4 kJ/kg I believe the answer is 295 but I am not sure
22. ### Chemistry (electron transfer)

Li^+(aq) + Zn(s) ? Li(s) + Zn^2+(aq) How many electrons are transferred in the balanced equation? I came up with an answer of 2, is this correct?
23. ### Chemistry

Okay. I've done what you said and found that the oxidation numbers for AgNO3 + NaCI = AgCI + NaNO3 do not change. This must not be redox.
24. ### Chemistry

I second guessed myself. The original answer I had was CH4+2O2=CO2+2H2O. Is this correct Dr. Bob?
25. ### Chemistry

Which reaction is NOT a redox reaction? CH4+2O2=CO2+2H2O 2Na+CI2=2NaCI AgNO3+NaCI=AgCI+NaNO3 KCIO3=KCI+3/2O2 I chose, KCIO3=KCI+3/2O2. Is this correct?
26. ### Chemistry

Silicon is an element that is directly below carbon on the periodic table. Silicon can form bonds similar to carbon. Silicon-silicon single bonds require 222 kJ/mol of energy to break. Based on the statements, how much energy would it take to break a carbon-carbon single bond...
27. ### Chem

Which of the following six-carbon molecules can be a straight-chain alkyne with two triple bonds and no double bonds? C6H4 C6H6 C6H8 C6H10 I chose C6H6, is this correct?
28. ### Chemistry

A hydrocarbon consists of a benzene ring and two methyl groups. The methyl groups are located at opposite carbons and the molecule is perfectly symmetrical. Which option correctly describes the numbers of the carbon atoms the methyl groups are bonded to? 2, 5 1, 2 2...
29. ### Chemistry (bonds)

Which formula represents a 5-carbon hydrocarbon ring with one double bond? C5H12 C5H5 C5H8 C5H7 I chose C5H8, is this correct?
30. ### Chemistry

I. C(s) + O2(g) ? CO2(g) ?Hf = ?394 kJ II. H2(g) + O2(g) ? H2O(l) ?Hf = ?242 kJ III. 2C(s) + 3H2(g) ? C2H6(g) ?H =?84 kJ The combustion of C2H6 is shown by the following equation: C2H6(g) + O2(g) ? 2CO2(g) + 3H2O(l) Which option correctly gives the enthalpy of combustion of 0....
31. ### Chemistry

Ammonia (NH3) ionizes according to the following reaction: NH3(aq) + H2O(l) ? NH4+(aq) + OH–(aq) The base dissociation constant for ammonia (NH3) is Kb = 1.8 × 10–5. Ammonia (NH3) also has a chloride salt, ammonium chloride (NH4Cl), which is soluble in water. ...
32. ### Chemistry

NH4Cl(s) ? NH3(g) + HCl(g) ?H°=176 kJ/mol At 25 °C, this reaction has a ?G° of 91.1 kJ/mol. What is the ?S° of this reaction? I came up with the solution of 0.896 kJ/mol. Is this correct?
33. ### Chemistry

CH4 + Cl2 ? CH4Cl + HCl Is this a double replacement reaction? I believe it is but am not entirely sure.
34. ### Chemistry (redox reaction)

Which reaction is a redox reaction? 1. HCI+H2O=H3O^+ +CI^- 2. H2SO4+2KOH=K2SO4+2H2O 3. CH4+2O2=CO2+2H2O 4. Fe^2+ +2OH^- =Fe(OH)2 I chose number 3, is this correct?
35. ### Chemistry

Al(s) + MnO2(s) ? Al2O3(s) + Mn(s) When this reaction is balanced, how many electrons are transferred in each half-reaction? The answer I got is 3*2=6. Is this correct?
36. ### Chemistry

Oh, I see. Thank you, Dr. Bob.
37. ### Chemistry

Study the two half reactions of an electrochemical cell. Ag(s) ? Ag^+(aq) + e^– E^0 = 0.80 V Cu(s) ? Cu^2+(aq) + 2e^– E^0 = 0.34 V Which option correctly gives the standard cell potential of Ag^+(aq) + Cu (s) ? 2Ag(s) + Cu^2+(aq) reaction? The answer I got is 0.46 ...
38. ### Chem (electron transfer)

KMnO4 + HCl ? MnCl2 + Cl2 + H2O + KCl If the reaction occurs in an acidic solution where water and H+ ions are added to the half-reactions to balance the overall reaction, how many electrons are transferred in the balanced reduction half-reaction? The answer I got is 5*2 ...
39. ### Chemistry (electron transfer)

I noticed that as well, Dr. Bob. I'm not quite sure why my teacher has it set up this way.
40. ### Chemistry (electron transfer)

MnO4^– + SO3^2– + H2O ? MnO2 + SO4^2– + OH^– If the reaction occurs in an acidic solution where water and H+ ions are added to the half-reactions to balance the overall reaction, how many electrons are transferred in the balanced reduction half-reaction? ...
41. ### Chem

NH4Cl(s) ? NH3(g) + HCl(g) ?H°=176 kJ/mol At 25 °C, this reaction has a ?G° of 91.1 kJ/mol. What is the ?S° of this reaction?
42. ### Chemistry

2A + 3B + C ? D + E The rate constant for this reaction is 0.25, and the reaction is second order in A and is first order in B and C. Which option correctly gives the rate of the reaction if [A] is 0.4 M, [B] is 0.1 M and [C] is 0.2 M?
43. ### Chemistry (equilibrium)

H2(g) + I2(g) ? 2HI(g) The concentration of H2, I2 and HI are measured as 0.04 M, 0.08 M and 0.12 M at equilibrium and 200 K. What is the value of equilibrium constant?
44. ### Chemistry

Ammonia (NH3) ionizes according to the following reaction: NH3(aq) + H2O(l) ? NH4+(aq) + OH–(aq) The base dissociation constant for ammonia (NH3) is Kb = 1.8 × 10–5. Ammonia (NH3) also has a chloride salt, ammonium chloride (NH4Cl), which is soluble in water. ...
45. ### Chemistry (concentration)

Iron fluoride (FeF2) dissociates according to the following equation: FeF2(s) ? Fe^2+(aq) + 2 F^–(aq) A sample of iron fluoride (FeF2) is dissolved in water, and a saturated solution is obtained. The [Fe^2+] is measured to be 2.05 × 10^–4 mol/L. What is the ...
46. ### Chem

CH3COOH(aq) + H2O(l) ? H3O^+(aq) + CH3COO^–(aq) [H3O^+] = 4.0 × 10^–3 M [CH3COOH] = 0.90 M What is the Ka value for the reaction?
47. ### Chemistry

Ammonia (NH3) ionizes according to the following reaction: NH3(aq)^+ H2O(l) ? NH4^+(aq) + OH^–(aq) The base dissociation constant for ammonia (NH3) is Kb = 1.8 × 10^–5. Ammonia (NH3) also has a chloride salt, ammonium chloride (NH4Cl), which is soluble in ...
48. ### Chemistry

The answer I ended up with is 0.05. Is that correct?
49. ### Chemistry

NH4Cl(s) ? NH3(g) + HCl(g) ?H°=176 kJ/mol At 25 °C, this reaction has a ?G° of 91.1 kJ/mol. What is the ?S° of this reaction?
50. ### Chemistry (spontaneous reaction)

Which of the given conditions leads to a negative free energy value (spontaneous reaction)? 1. Highly positive enthalpy and highly negative entropy 2. Slightly negative enthalpy and highly negative entropy 3. Highly positive enthalpy and slightly positive entropy 4. Highly ...
51. ### Chem

Zinc fluoride (ZnF2) dissociates according to the following equation: ZnF2(s) ? Zn2+(aq) + 2F–(aq) Ksp of this equilibrium is 3.0 × 10–2. If the concentration of zinc ions (Zn2+) in a solution is measured to be 4.4 × 10–1 M, what is the ...
52. ### Chemistry

Calcium fluoride (CaF2) is a slightly soluble salt, which dissociates in water according to the following reaction: CaF2(s) ? Ca2+(aq) + 2F–(aq) What is the solubility product constant for this reaction?
53. ### Chem

A 0.2 M KOH solution has a volume of 3 L. What percent of water should be evaporated to obtain a 0.6 M KOH solution? The answer I got is, 66.7%
54. ### Chemistry

During a titration experiment, a 150.0 mL solution of 0.05 M sulfuric acid (H2SO4) is neutralized by 300.0 mL solution with an unknown concentration of sodium hydroxide (NaOH). What is the concentration of the sodium hydroxide solution? The answer I got is, 0.25 M
55. ### Chemistry

The solubility of sugar is 204 g/ 100 g water at 20 °C. How many grams of water are needed to dissolve 612 grams of sugar at the same temperature?
56. ### Chemistry (concentration)

A 200 mL NaCl solution with a concentration of 4.0 g/L is mixed with a 600 mL solution containing 8% NaCl (m/v). What is the final concentration of salt in the solution in g/L?
57. ### Chemistry

H2SO4(aq) + H2O(l) ? H3O+(aq) + HSO4–(aq) (Stage I) Identify the Brønsted-Lowry acid and base in the reaction.
58. ### Chemistry (mol)

2CO + O2 ? 2CO2 If 3.4 moles of carbon dioxide (CO2) form at the end of the reaction, how many moles of carbon monoxide (CO) and oxygen gas (O2) entered the reaction?
59. ### Chemistry (volume)

The molarity of a sodium hydroxide solution is 0.2 M. The molar mass of NaOH is 40 g/mol. If 20 g of sodium hydroxide (NaOH) is dissolved in water in this solution, what is the volume of the solution?
60. ### Chemistry

During a titration experiment, a 150.0 mL solution of 0.05 M sulfuric acid (H2SO4) is neutralized by 300.0 mL solution with an unknown concentration of sodium hydroxide (NaOH). What is the concentration of the sodium hydroxide solution?
61. ### Chemistry (evaporation)

What percentage would that be?
62. ### Chemistry (evaporation)

A 0.2 M KOH solution has a volume of 3 L. What percent of water should be evaporated to obtain a 0.6 M KOH solution?
63. ### Chem

What is the pOH of a 5.0 ×10-5 M hydrochloric acid (HCl) solution at 25° C?
64. ### Chemistry

Thank you, Scott!
65. ### Chemistry

A pool is filled with 24.0 liters of a chlorine-water solution with 8.00 ppm of chlorine. How many milligrams of chlorine are in the pool?
66. ### Chemistry

So what does that mean exactly?
67. ### Chemistry

What is the relation between pH and pOH? Is the relation positive, negative or neutral?
68. ### Chemistry (volume of gas)

I have tried these calculations. I believe the answer is 6.1, is this correct?
69. ### Chemistry (volume of gas)

A sample of argon at 2.0 atm pressure is heated until its temperature is raised from 60 °C to 90 °C. The pressure of the gas at this temperature is 3.0 atm and the volume is 4.4 L. What was the initial volume of the gas?
70. ### Chemistry

Thank you very much Damon and DrBob! I appreciate your help!
71. ### Chemistry

Could the answer be 4.5?
72. ### Chemistry

101325*V=16*62.36, this is the equation I came up with with the ideal gas law. I cannot seem to come up with the correct formula.
73. ### Chemistry

The answer would be 45.0, correct?
74. ### Chemistry

3.2 grams of CH4 gas applies 760 mmHg pressure at 273 K temperature. Assume ideal gas behavior. The ideal gas constant is 62.36 (L· mmHg)/(K·mol), and the molecular mass of CH4 is 16 g/mol. How much volume does the gas occupy?
75. ### Chem

Water has a larger specific heat?
76. ### Chem

Does water have a stronger intermolecular force than liquid ethanol?
77. ### Chemistry

Use the heating curve of 50 g of water and the list of values to answer the question. specific heat of ice = 2.10 J/(g·°C) specific heat of water = 4.18 J/(g·°C) specific heat of water vapor = 2.07 J/(g·°C) latent heat of fusion of ice = 333.4 ...
78. ### Chem

742.5 J of energy is used to heat an unknown mass of aluminum from 10° C to 65.0° C. The specific heat capacity of aluminum = 0.90 J/(g·°C). What is the mass of the aluminum?
79. ### Chemistry (partial pressure)

A mixture consists of 3.2 grams of CH4 gas and 1.2 grams of H2 in a steel container. The pressure inside the container is 6.0 atm. The molecular mass of CH4 is 16 g/mol, and the molecular mass of H2 gas is 2 g/mol. What is the partial pressure of H2?
80. ### Chemistry

If the latent heat of fusion for water is 333.4 J/g, how much heat is required to melt 170 grams of ice at 0 °C?

It is 10
82. ### math

I need to know what is 153 divided by 1,000
83. ### Chemistry

I do not understand how to do it still.
84. ### Chemistry

Study the balanced equation. 3O_2=2O_3 When 4.26 x 1016 mol of oxygen (O) are converted into ozone, how many mol of the pollutant (O3) are formed?
85. ### Chemistry (mol)

How many particles are in 9.22 x 10–37 mol of iron(III) oxide (Fe2O3)? 5.55 * 10^-13 mol Fe2O3 5.54 * 10^12 mol Fe2O3 1.47 * 10^-23 mol Fe2O3 1.60 * 10^23 mol Fe2O3
86. ### Chemistry (mol)

Xe+3F_2=XeF_6 How many mol of xenon hexafluoride are produced from 4.01 x 102 mol of fluorine (F2)?
87. ### Chemistry

Study the balanced equation. 3O_2=2O_3 When 4.26 x 10^16 mol of oxygen (O) are converted into ozone, how many mol of the pollutant (O3) are formed?
88. ### Chemistry (mol)

How many mol of nitrogen monoxide gas (N2) are in a 1.49 L container at standard temperature and pressure?
89. ### Chemistry

The procedures of an experiment state that 1.3 g of copper (Cu) should be produced. However, the scientist’s experiment produces 0.9 g. What is the absolute error?
90. ### Chemistry

Thanks, DrBob222. I have a few more questions, could you help me?
91. ### Chemistry

If SiO_2 undergoes a double-displacement reaction with HF, what is the balanced equation?
92. ### Calculus

Oblique tracking. A ship leaves port traveling southwest at a rate of 12 mi/hr. at noon, the ship reaches its closest approach to a radar station, which is on the shor 1.5 miles from the port. if the ship maintains its speed and course, what is the rate of change of the ...
93. ### Calculus

Imagine slicing through a sphere with a plane (sheet of paper). the smaller piece produced is called a radius of the sphere. Its volume is V=(pi)h^2(3r-h)/3, where r is the radius of the sphere and h is the thickness of the cap. find dr/dh for a sphere with a volume of 5pi/3m^...
94. ### English

Which of the following sentences is punctuated correctly? a) The ladies’s hats were all purple; they looked so pretty. b) The strong heavyset fighter won his first fight, and was featured in the newspaper. c) The horse rode to our house, the beach, and around the church, ...

Thank you
96. ### English

1.The rules for lighting are not always this simple, but the possibilities are endless. 2.The secret to taking beautiful photographs is an understanding of composition and lighting. 3. When both composition and lighting are well considered, a fantastic photo is just a click ...
97. ### chemistry

The density of diamond is 3.51g/cm^3,and the density of platinum is 21.43g/cm^3.If equal masses of diamond and platinum are transferred to equal volumes of water in separate graduated cylinders,which graduated cylinder would have the greatest volume change? can you show me a ...
98. ### chemistry

The density of diamond is 3.51 g/cm^3 and the density of platinum is 21.43g/cm^3. If equal masses of diamond and platinum are transferred to equal volumes of water in separate graduated cylinders, which graduated cylinder would have the greatest volume change? Explain or show ...
99. ### Algebra 8th

For each sequence defined recursively, write the first few terms. Then use the terms to write an explicit equation. a(1)=17 a(n+1)=a(n)-3 And a(1) =20. a(n+1)=1/2*a(n)
100. ### social studies

What was the long-term effect of the Magna Carta? a. A weakening of power of feudal lords. B. The surrender of French territory to English rule. C. The rise of strong trading cities . D. The development of more democratic government? WHAT'S THE ANSWER
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