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Determine the pH of
(a) a 0.15 M NH3 solution.
(b) a solution that is 0.15 M NH3 and 0.40 M NH4Cl.
Kb for NH3 is 1.8 × 10−5
In: Chemistry
| NOTE: If more than one bond angle is possible, separate each with a space. For example, trigonal bipyramid geometry can lead to 3 different bond angles. Octahedral geometry can lead to 2. |
A. What is the hybridization of the central atom
in BrF5?
| Hybridization = |
What are the approximate bond angles in this substance ?
Bond angles =
In: Chemistry
In the lab, a 2.00 x 10-4 M FeSCN2+ stock solution will be provided. Calculate the volume of stock solution (in mL) required to prepare a 10.00 mL 1.50 x 10-4 M solution. Report your answer to two decimal places. Example: If the calculated volume is 1.2 mL, input 1.20. Exclude units in your answer.
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Part A: A calorimeter contains 18.0 mL of water at 13.5∘C. When 2.30 g of X (a substance with a molar mass of 69.0 g/mol) is added, it dissolves via the reaction X(s)+H2O(l)→X(aq) and the temperature of the solution increases to 30.0∘C. Calculate the enthalpy change, ΔH, for this reaction per mole of X. Assume that the specific heat of the resulting solution is equal to that of water [4.18 J/(g⋅∘C)], that density of water is 1.00 g/mL, and that no heat is lost to the calorimeter itself, nor to the surroundings. Part B: the reaction C12H22O11(s)+12O2(g)→12CO2(g)+11H2O(l) in which 10.0 g of sucrose, C12H22O11, was burned in a bomb calorimeter with a heat capacity of 7.50 kJ/∘C. The temperature increase inside the calorimeter was found to be 22.0∘C. Calculate the change in internal energy, ΔE, for this reaction per mole of sucrose.
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Explain how alloys based on the base material titanium and nickel can be cured.
What curing mechanisms can be used and what are the most important mechanism (creating the most stretch limit increase) that can be created through heat treatments and how do they disrupt the mechanism in each system?
In: Chemistry
A.
Calculate the enthalpy change, ΔH, for the process in which 49.3 g of water is converted from liquid at 18.5 ∘C to vapor at 25.0 ∘C .
For water, ΔHvap = 44.0 kJ/mol at 25.0 ∘C ands = 4.18 J/(g⋅∘C) for H2O(l)
B.
How many grams of ice at -6.4 ∘C can be completely converted to liquid at 12.3 ∘C if the available heat for this process is 5.33×103 kJ ?
For ice, use a specific heat of 2.01 J/(g⋅∘C) and ΔHfus = 6.01 kJ/mol .
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Aqueous sulfuric acid H2SO4 reacts with solid sodium hydroxide NaOH to produce aqueous sodium sulfate Na2SO4 and liquid water H2O. If 6.41gof sodium sulfate is produced from the reaction of 7.8g of sulfuric acid and 4.4g of sodium hydroxide, calculate the percent yield of sodium sulfate.
Be sure your answer has the correct number of significant digits in it.
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Write the balanced chemical equation for each of these reactions. Include phases.
1) When aqueous sodium hydroxide is added to a solution containing lead(II) nitrate, a solid precipitate forms.
2) However, when additional aqueous hydroxide is added the precipitate redissolves forming a soluble [Pb(OH)4]2-(aq) complex ion.
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Complete and balance the following equations for gass-evolution reactions.
(NH4)2SO4 (aq) + KOH (aq) ------>
Express your answer as a chemical equation. Identify all of the phases in your answer please.
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A 33.153 mg sample of a chemical known to contain only carbon, hydrogen, sulfur, and oxygen is put into a combustion analysis apparatus, yielding 59.060 mg of carbon dioxide and 24.176 mg of water. In another experiment, 21.223 mg of the compound is reacted with excess oxygen to produce 9.1726 mg of sulfur dioxide. Add subscripts below to correctly identify the empirical formula of this compound (use this order of elements: CHSO)
In: Chemistry
calculate Ecell for each of the following cells.
Al(s)|Al3+( 0.20M )||Fe2+( 0.90M )|Fe(s)
Ag(s)|Ag+( 0.38M )||Cl-( 0.094M )|Cl2(g, 0.60atm )|Pt(s)
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Describe a method that can be used to separate each of the following mixtures of metal ions.
A. Ag+, Pb2+
B. Mn2+, Fe3+
C. Ni2+, Al3+
D. Cu2+, Ni2+
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You mix 50.0 mL of a weak monoprotic acid with 50.0 mL of NaOH solution in a coffee cup calorimeter. Both solutions (and the calorimeter) were initially at 22.0C. The final temperature of the neutralization reaction was determined to be 22.5C.
a) What is the total amount of heat evolved in this reaction? Show all work.
b) If 0.135 moles of the monoprotic acid were neutralized in this reaction, what is the molar heat of neutralization (enthalpy) for this reaction?
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An alloy is composed of elements A (78%) and B (12%) by weight. The density of the alloy is 1.95 g/cm3. The properties of these elements are shown below:
|
Element |
Gram Atomic Weight |
σa (barns) |
σs (barns) |
|
A |
22.1999 |
0.19 |
1.38 |
|
B |
25.0055 |
0.21 |
2.44 |
Determine:
The atom densities for the two elements.
The atomic density for element A:
b. The absorption and scattering macroscopic cross sections for thermal neutrons.
c. The mean free paths for absorption and scattering.
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Determine the pH of each of the following solutions. Part A 0.17 M KCHO 2 Part B 0.24 M CH 3 NH 3 I Part C 0.16 M KI
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